Docker run リファレンス
Docker は隔離されたコンテナー内でプロセスを実行します。
コンテナーとは、ホスト上で実行される 1 つのプロセスです。
ここでいうホストは、ローカルとリモートのどちらもあります。
docker run
を実行すると、分離された状態でコンテナープロセスが起動します。
そこではホストから切り離されたところで、独自のファイルシステム、独自のネットワーク、分離されたプロセスツリーを持ちます。
このページでは、コンテナーのリソースを実行時に定義して docker run
コマンドを利用する方法を示します。
一般的な書式
基本的な docker run
コマンドは以下の書式で表わされます。
$ docker run [オプション] IMAGE[:TAG|@DIGEST] [COMMAND] [ARG...]
docker run
コマンドには イメージ を指定することが必要です。
コンテナーはこのイメージから作り出されます。
イメージの開発者は、以下に関するデフォルトをイメージに定義することができます。
- デタッチ実行かフォアグラウンド実行か
- コンテナーの指定
- ネットワーク設定
- CPU やメモリに対する実行時の制約
docker run [オプション]
を使うと、開発者が設定したイメージデフォルトを追加またはオーバーライドすることができます。
またオペレーターは、Docker ランタイムに設定されているデフォルト値を、ほぼすべてオーバーライドすることができます。
このようにオペレーターに対して、イメージや Docker ランタイムに対するデフォルト値のオーバーライドを可能としているため、docker
コマンドの中でも run コマンドには、多くのオプションが存在しています。
[オプション]
の種類を理解するには オプションの種類 を参照してください。
メモ: Docker に対するシステム設定の仕方によっては、
docker run
コマンドの実行時にsudo
をつけることが必要かもしれません。sudo
をつけずにdocker
コマンドを実行できるようにするには、システム管理者がdocker
という名のグループを生成して、そこにユーザーを追加するようにします。 この設定に関する詳細は、各オペレーティングシステムにおける Docker インストールのドキュメントを参照してください。
オペレーター専用のオプション
オペレーター（docker run
を実行するユーザー）だけが利用できるのが、以下のオプションです。
- デタッチ実行かフォアグラウンド実行か
- Container identification
- IPC settings (--ipc)
- Network settings
- 再起動ポリシー (--restart)
- Clean up (--rm)
- Runtime constraints on resources
- Runtime privilege and Linux capabilities
デタッチ実行かフォアグラウンド実行か
Docker コンテナーの起動時には、コンテナーを「デタッチ」（detached）モードによりバックグラウンドで実行するか、デフォルトのフォアグラウンドモードで実行するかを取り決めておく必要があります。
-d=false: Detached mode: Run container in the background, print new container id
デタッチ起動 (-d)
デタッチモードでコンテナーを起動するには、-d=true
または単に -d
オプションを利用します。
設計方針として、デタッチモードで起動したコンテナーが終了するのは、コンテナーの起動に用いられたルートプロセスが終了したときとなっています。
ただし --rm
オプションも合わせて指定した場合は異なります。
-d
と同時に --rm
を指定した場合は、コンテナーが終了するか、あるいは デーモンが終了するか、どちらかが先に起きたときに、コンテナーは削除されます。
service
かつ start
コマンドをデタッチコンテナーに対して用いてはなりません。
例として、以下のコマンドは nginx
サービスを起動するものです。
$ docker run -d -p 80:80 my_image service nginx start
このコマンドは、コンテナー内に nginx
サービスを起動させることには成功します。
しかしデタッチ実行という処理には失敗します。
そしてルートプロセス（service nginx start
）が終了してデタッチコンテナーが停止しますが、これは設計どおりの動きです。
結果として nginx
サービスは起動するものの、利用はできません。
nginx
ウェブサーバーのようなプロセスを起動するなら、代わりに以下のようなコマンド実行とします。
$ docker run -d -p 80:80 my_image nginx -g 'daemon off;'
デタッチコンテナーを使って入出力を行うには、ネットワーク接続や共有ボリュームを利用します。
これが必要になる理由は、docker run
を実行したコマンドラインから、コンテナーはもはやコマンドを受け付ける状態にはないからです。
デタッチモードのコンテナーに再度アタッチするには docker
attach コマンドを利用します。
フォアグラウンド起動
フォアグラウンドモード（-d
を指定しなかった場合のデフォルト）の場合、docker run
はコンテナー内にプロセスを起動させます。
そしてコンソールをプロセスの標準入出力および標準エラー出力にアタッチします。
こうすれば TTY であるかのように扱うことができ（そしてたいていのコマンドラインモジュールが期待していることであり）、シグナルの送受信も行うことができます。
いずれも設定により変更可能です。
-a=[] : `STDIN`, `STDOUT`, `STDERR` にアタッチします。
-t : 擬似TTYに割り当てます。
--sig-proxy=true: 受信シグナルをすべてプロセスにプロキシーします。(非TTYモードのみ)
-i : アタッチされていなくても STDIN だけは受け付けます。
-a
を指定しなかった場合、Docker は 標準出力と標準エラー出力の双方にアタッチ します。
上とは別に、標準ストリーム 3 つ（STDIN
, STDOUT
, STDERR
）のうちから、接続したいものを選んで指定することもできます。
たとえば以下のようにします。
$ docker run -a stdin -a stdout -i -t ubuntu /bin/bash
シェルのような対話的処理を行うには、-i -t
をともに指定し、コンテナープロセスに対して TTY を割り当てることが必要です。
-i -t
は後の利用例からもわかるように、-it
と記述する場合もあります。
クライアントが標準入力をパイプから受け付けている場合は、-t
の指定は禁止されています。
たとえば以下です。
$ echo test | docker run -i busybox cat
メモ: コンテナー内にて PID 1 として実行しているプロセスは、Linux において特別に取り扱われるものです。 このプロセスのデフォルト動作は、あらゆるシグナルを無視します。 したがってこのプロセスが特別にコーディングされていない限り、
SIGINT
やSIGTERM
では停止しません。
コンテナーの指定
コンテナー名 (--name)
オペレーターがコンテナーを指定するには、以下の 3 とおりの方法があります。
| 識別タイプ | 利用例 |
|---|---|
| UUID 識別子(長い) | “f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778” |
| UUID 識別子(短い) | “f78375b1c487” |
| 名前 | “evil_ptolemy” |
UUID 識別子は Docker デーモンから割り当てられるものです。
--name
オプションによりコンテナー名を指定しなかった場合、デーモンはランダムな文字列を生成して割り当てます。
name
を定義すれば、コンテナーに意味のある名称を与えることができます。
name
を指定しておくと、Docker ネットワーク内のコンテナーを参照する際に、その名前を使うことができます。
この方法は Docker コンテナーの実行が、バックグラウンドかフォアグラウンドかに関係なく利用できます。
メモ: デフォルトのブリッジネットワーク上のコンテナーが、その名前を使って通信するためには互いにリンクしておくことが必要です。
PID に相当するもの
処理の自動化に活用するような目的で、コンテナー ID を指定ファイルに書き出すことができます。 これはある種のプログラムにおいて、プロセス ID をファイルに書き出している手法と同様です。 （PID ファイルとして見たことがあるものです。）
--cidfile="": コンテナーIDをファイルに書き出します。
イメージ[:タグ]
コンテナーを厳密に指定する方法ではありませんが、実行したいコンテナーのイメージバージョンを指定することが可能です。
これを行うには、コマンド実行時に イメージ[:タグ]
を加えます。
たとえば docker run ubuntu:14.04
のようにします。
イメージ[@ダイジェスト値]
Images using the v2 or later image format have a content-addressable identifier called a digest. As long as the input used to generate the image is unchanged, the digest value is predictable and referenceable.
The following example runs a container from the alpine
image with the
sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0
digest:
$ docker run alpine@sha256:9cacb71397b640eca97488cf08582ae4e4068513101088e9f96c9814bfda95e0 date
PID 設定 (--pid)
--pid="" : Set the PID (Process) Namespace mode for the container,
'container:<name|id>': joins another container's PID namespace
'host': use the host's PID namespace inside the container
コンテナーの PID 名前空間は、デフォルトで有効になっています。
PID 名前空間は、プロセスの分離を実現します。 PID 名前空間があることによって、システムプロセスの参照はできなくなり、プロセス ID の再利用が（PID 1 を含めて）可能となります。
コンテナーがホストプロセスの名前空間を共有したい場合を考えます。
この場合、基本的にはコンテナー内部のプロセスが、システム上の全プロセスを参照できるようにします。
たとえば strace
や gdb
といったデバッグツールを用いてコンテナーをビルドしたとして、このツールをコンテナー内部のプロセスをデバッグする際にも利用したい場合です。
利用例: コンテナー内での htop の実行
以下の Dockerfile を生成します。
FROM alpine:latest
RUN apk add --update htop && rm -rf /var/cache/apk/*
CMD ["htop"]
Dockerfile をビルドして、イメージに対して myhtop
というタグをつけます。
$ docker build -t myhtop .
以下のコマンドを実行して、コンテナー内にて htop
を実行します。
$ docker run -it --rm --pid=host myhtop
別コンテナーが PID 名前空間に参加すれば、コンテナーをデバッグする目的で利用することができます。
利用例
Start a container running a redis server:
$ docker run --name my-redis -d redis
Debug the redis container by running another container that has strace in it:
$ docker run -it --pid=container:my-redis my_strace_docker_image bash
$ strace -p 1
UTS 設定 (--uts)
--uts="" : Set the UTS namespace mode for the container,
'host': use the host's UTS namespace inside the container
The UTS namespace is for setting the hostname and the domain that is visible
to running processes in that namespace. By default, all containers, including
those with --network=host
, have their own UTS namespace. The host
setting will
result in the container using the same UTS namespace as the host. Note that
--hostname
and --domainname
are invalid in host
UTS mode.
You may wish to share the UTS namespace with the host if you would like the hostname of the container to change as the hostname of the host changes. A more advanced use case would be changing the host’s hostname from a container.
IPC settings (--ipc)
--ipc="MODE" : Set the IPC mode for the container
The following values are accepted:
| Value | Description |
|---|---|
| ”” | Use daemon’s default. |
| “none” | Own private IPC namespace, with /dev/shm not mounted. |
| “private” | Own private IPC namespace. |
| “shareable” | Own private IPC namespace, with a possibility to share it with other containers. |
| “container: <_name-or-ID_>" | Join another (“shareable”) container’s IPC namespace. |
| “host” | Use the host system’s IPC namespace. |
If not specified, daemon default is used, which can either be "private"
or "shareable"
, depending on the daemon version and configuration.
IPC (POSIX/SysV IPC) namespace provides separation of named shared memory segments, semaphores and message queues.
Shared memory segments are used to accelerate inter-process communication at
memory speed, rather than through pipes or through the network stack. Shared
memory is commonly used by databases and custom-built (typically C/OpenMPI,
C++/using boost libraries) high performance applications for scientific
computing and financial services industries. If these types of applications
are broken into multiple containers, you might need to share the IPC mechanisms
of the containers, using "shareable"
mode for the main (i.e. “donor”)
container, and "container:<donor-name-or-ID>"
for other containers.
ネットワーク設定
--dns=[] : Set custom dns servers for the container
--network="bridge" : Connect a container to a network
'bridge': create a network stack on the default Docker bridge
'none': no networking
'container:<name|id>': reuse another container's network stack
'host': use the Docker host network stack
'<network-name>|<network-id>': connect to a user-defined network
--network-alias=[] : Add network-scoped alias for the container
--add-host="" : Add a line to /etc/hosts (host:IP)
--mac-address="" : Sets the container's Ethernet device's MAC address
--ip="" : Sets the container's Ethernet device's IPv4 address
--ip6="" : Sets the container's Ethernet device's IPv6 address
--link-local-ip=[] : コンテナーのイーサネットデバイスに 1つまたは複数のIPv4/IPv6によるリンクローカルアドレスを設定します。
By default, all containers have networking enabled and they can make any
outgoing connections. The operator can completely disable networking
with docker run --network none
which disables all incoming and outgoing
networking. In cases like this, you would perform I/O through files or
STDIN
and STDOUT
only.
Publishing ports and linking to other containers only works with the default (bridge). The linking feature is a legacy feature. You should always prefer using Docker network drivers over linking.
Your container will use the same DNS servers as the host by default, but
you can override this with --dns
.
By default, the MAC address is generated using the IP address allocated to the
container. You can set the container’s MAC address explicitly by providing a
MAC address via the --mac-address
parameter (format:12:34:56:78:9a:bc
).Be
aware that Docker does not check if manually specified MAC addresses are unique.
Supported networks :
| ネットワーク | 内容説明 |
|---|---|
| none | No networking in the container. |
| bridge (default) | Connect the container to the bridge via veth interfaces. |
| host | Use the host's network stack inside the container. |
| container:<name|id> | Use the network stack of another container, specified via its name or id. |
| NETWORK | Connects the container to a user created network (using docker network create command) |
ネットワーク設定: none
With the network is none
a container will not have
access to any external routes. The container will still have a
loopback
interface enabled in the container but it does not have any
routes to external traffic.
ネットワーク設定: bridge
コンテナーに対して bridge
を設定した場合、そのネットワークは Docker のデフォルトネットワーク設定を利用します。
ブリッジはホスト上において、通常は docker0
という名前で設定されます。
そしてコンテナーに対しては veth
というインターフェースがペアで生成されます。
この veth
ペアの一方は、ブリッジにアタッチされたホスト上にあり、もう一方はコンテナーの名前空間内に置かれます。
その名前空間内には loopback
インターフェースもあります。
ブリッジネットワーク上のコンテナーに対して IP アドレスが割り振られるので、トラフィックはこのブリッジを介してコンテナーに届けられます。
コンテナー同士は、デフォルトではその IP アドレスを使って互いに通信を行います。 名前を使って通信を行うには、互いにリンクしていなければなりません。
ネットワーク設定: host
With the network set to host
a container will share the host’s
network stack and all interfaces from the host will be available to the
container. The container’s hostname will match the hostname on the host
system. Note that --mac-address
is invalid in host
netmode. Even in host
network mode a container has its own UTS namespace by default. As such
--hostname
and --domainname
are allowed in host
network mode and will
only change the hostname and domain name inside the container.
Similar to --hostname
, the --add-host
, --dns
, --dns-search
, and
--dns-option
options can be used in host
network mode. These options update
/etc/hosts
or /etc/resolv.conf
inside the container. No change are made to
/etc/hosts
and /etc/resolv.conf
on the host.
Compared to the default bridge
mode, the host
mode gives significantly
better networking performance since it uses the host’s native networking stack
whereas the bridge has to go through one level of virtualization through the
docker daemon. It is recommended to run containers in this mode when their
networking performance is critical, for example, a production Load Balancer
or a High Performance Web Server.
Note:
--network="host"
gives the container full access to local system services such as D-bus and is therefore considered insecure.
Network: container
With the network set to container
a container will share the
network stack of another container. The other container’s name must be
provided in the format of --network container:<name|id>
. Note that --add-host
--hostname
--dns
--dns-search
--dns-option
and --mac-address
are
invalid in container
netmode, and --publish
--publish-all
--expose
are
also invalid in container
netmode.
Example running a Redis container with Redis binding to localhost
then
running the redis-cli
command and connecting to the Redis server over the
localhost
interface.
$ docker run -d --name redis example/redis --bind <IP_ADDRESS>
$ # use the redis container's network stack to access localhost
$ docker run --rm -it --network container:redis example/redis-cli -h <IP_ADDRESS>
User-defined network
You can create a network using a Docker network driver or an external network driver plugin. You can connect multiple containers to the same network. Once connected to a user-defined network, the containers can communicate easily using only another container’s IP address or name.
For overlay
networks or custom plugins that support multi-host connectivity,
containers connected to the same multi-host network but launched from different
Engines can also communicate in this way.
The following example creates a network using the built-in bridge
network
driver and running a container in the created network
$ docker network create -d bridge my-net
$ docker run --network=my-net -itd --name=container3 busybox
Managing /etc/hosts
Your container will have lines in /etc/hosts
which define the hostname of the
container itself as well as localhost
and a few other common things. The
--add-host
flag can be used to add additional lines to /etc/hosts
.
$ docker run -it --add-host db-static:<IP_ADDRESS> ubuntu cat /etc/hosts
<IP_ADDRESS> 09d03f76bf2c
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
<IP_ADDRESS> localhost
::1 localhost ip6-localhost ip6-loopback
<IP_ADDRESS> db-static
If a container is connected to the default bridge network and linked
with other containers, then the container’s /etc/hosts
file is updated
with the linked container’s name.
Note Since Docker may live update the container’s
/etc/hosts
file, there may be situations when processes inside the container can end up reading an empty or incomplete/etc/hosts
file. In most cases, retrying the read again should fix the problem.
Restart policies (--restart)
Using the --restart
flag on Docker run you can specify a restart policy for
how a container should or should not be restarted on exit.
When a restart policy is active on a container, it will be shown as either Up
or Restarting
in docker ps
. It can also be
useful to use docker events
to see the
restart policy in effect.
Docker supports the following restart policies:
| ポリシー | Result |
|---|---|
| no | Do not automatically restart the container when it exits. This is the default. |
| on-failure[:max-retries] | Restart only if the container exits with a non-zero exit status. Optionally, limit the number of restart retries the Docker daemon attempts. |
| always | Always restart the container regardless of the exit status. When you specify always, the Docker daemon will try to restart the container indefinitely. The container will also always start on daemon startup, regardless of the current state of the container. |
| unless-stopped | Always restart the container regardless of the exit status, including on daemon startup, except if the container was put into a stopped state before the Docker daemon was stopped. |
An ever increasing delay (double the previous delay, starting at 100
milliseconds) is added before each restart to prevent flooding the server.
This means the daemon will wait for 100 ms, then 200 ms, 400, 800, 1600,
and so on until either the on-failure
limit is hit, or when you docker stop
or docker rm -f
the container.
If a container is successfully restarted (the container is started and runs for at least 10 seconds), the delay is reset to its default value of 100 ms.
You can specify the maximum amount of times Docker will try to restart the
container when using the on-failure policy. The default is that Docker
will try forever to restart the container. The number of (attempted) restarts
for a container can be obtained via docker inspect
. For example, to get the number of restarts
for container “my-container”;
$ docker inspect -f "{{ .RestartCount }}" my-container
# 2
Or, to get the last time the container was (re)started;
$ docker inspect -f "{{ .State.StartedAt }}" my-container
# 2015-03-04T23:47:07.691840179Z
Combining --restart
(restart policy) with the --rm
(clean up) flag results
in an error. On container restart, attached clients are disconnected. See the
examples on using the --rm
(clean up) flag later in this page.
利用例
$ docker run --restart=always redis
This will run the redis
container with a restart policy of always
so that if the container exits, Docker will restart it.
$ docker run --restart=on-failure:10 redis
This will run the redis
container with a restart policy of on-failure
and a maximum restart count of 10. If the redis
container exits with a
non-zero exit status more than 10 times in a row Docker will abort trying to
restart the container. Providing a maximum restart limit is only valid for the
on-failure policy.
Exit Status
The exit code from docker run
gives information about why the container
failed to run or why it exited. When docker run
exits with a non-zero code,
the exit codes follow the chroot
standard, see below:
125 if the error is with Docker daemon itself
$ docker run --foo busybox; echo $?
# flag provided but not defined: --foo
See 'docker run --help'.
125
126 if the contained command cannot be invoked
$ docker run busybox /etc; echo $?
# docker: Error response from daemon: Container command '/etc' could not be invoked.
126
127 if the contained command cannot be found
$ docker run busybox foo; echo $?
# docker: Error response from daemon: Container command 'foo' not found or does not exist.
127
Exit code of contained command otherwise
$ docker run busybox /bin/sh -c 'exit 3'; echo $?
# 3
Clean up (--rm)
By default a container’s file system persists even after the container
exits. This makes debugging a lot easier (since you can inspect the
final state) and you retain all your data by default. But if you are
running short-term foreground processes, these container file
systems can really pile up. If instead you’d like Docker to
automatically clean up the container and remove the file system when
the container exits, you can add the --rm
flag:
--rm=false: Automatically remove the container when it exits
Note: When you set the
--rm
flag, Docker also removes the anonymous volumes associated with the container when the container is removed. This is similar to runningdocker rm -v my-container
. Only volumes that are specified without a name are removed. For example, withdocker run --rm -v /foo -v awesome:/bar busybox top
, the volume for/foo
will be removed, but the volume for/bar
will not. Volumes inherited via--volumes-from
will be removed with the same logic -- if the original volume was specified with a name it will not be removed.
Security configuration
--security-opt="label=user:USER" : Set the label user for the container
--security-opt="label=role:ROLE" : Set the label role for the container
--security-opt="label=type:TYPE" : Set the label type for the container
--security-opt="label=level:LEVEL" : Set the label level for the container
--security-opt="label=disable" : Turn off label confinement for the container
--security-opt="apparmor=PROFILE" : Set the apparmor profile to be applied to the container
--security-opt="no-new-privileges:true|false" : Disable/enable container processes from gaining new privileges
--security-opt="seccomp=unconfined" : Turn off seccomp confinement for the container
--security-opt="seccomp=profile.json": White listed syscalls seccomp Json file to be used as a seccomp filter
You can override the default labeling scheme for each container by specifying
the --security-opt
flag. Specifying the level in the following command
allows you to share the same content between containers.
$ docker run --security-opt label=level:s0:c100,c200 -it fedora bash
Note: Automatic translation of MLS labels is not currently supported.
To disable the security labeling for this container versus running with the
--privileged
flag, use the following command:
$ docker run --security-opt label=disable -it fedora bash
If you want a tighter security policy on the processes within a container, you can specify an alternate type for the container. You could run a container that is only allowed to listen on Apache ports by executing the following command:
$ docker run --security-opt label=type:svirt_apache_t -it centos bash
Note: You would have to write policy defining a
svirt_apache_t
type.
If you want to prevent your container processes from gaining additional privileges, you can execute the following command:
$ docker run --security-opt no-new-privileges -it centos bash
This means that commands that raise privileges such as su
or sudo
will no longer work.
It also causes any seccomp filters to be applied later, after privileges have been dropped
which may mean you can have a more restrictive set of filters.
For more details, see the kernel documentation.
Specify an init process
You can use the --init
flag to indicate that an init process should be used as
the PID 1 in the container. Specifying an init process ensures the usual
responsibilities of an init system, such as reaping zombie processes, are
performed inside the created container.
The default init process used is the first docker-init
executable found in the
system path of the Docker daemon process. This docker-init
binary, included in
the default installation, is backed by tini.
Specify custom cgroups
Using the --cgroup-parent
flag, you can pass a specific cgroup to run a
container in.  You can
define custom resources for those cgroups and put containers under a common
parent group.
Runtime constraints on resources
The operator can also adjust the performance parameters of the container:
| オプション | 内容説明 |
|---|---|
-m , --memory="" |
Memory limit (format: <number>[<unit>] ). Number is a positive integer. Unit can be one of b , k , m , or g . Minimum is 4M. |
--memory-swap="" |
Total memory limit (memory + swap, format: <number>[<unit>] ). Number is a positive integer. Unit can be one of b , k , m , or g . |
--memory-reservation="" |
Memory soft limit (format: <number>[<unit>] ). Number is a positive integer. Unit can be one of b , k , m , or g . |
--kernel-memory="" |
Kernel memory limit (format: <number>[<unit>] ). Number is a positive integer. Unit can be one of b , k , m , or g . Minimum is 4M. |
-c , --cpu-shares=0 |
CPU shares (relative weight) |
--cpus=0.000 |
Number of CPUs. Number is a fractional number. 0.000 means no limit. |
--cpu-period=0 |
Limit the CPU CFS (Completely Fair Scheduler) period |
--cpuset-cpus="" |
CPUs in which to allow execution (0-3, 0,1) |
--cpuset-mems="" |
Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effective on NUMA systems. |
--cpu-quota=0 |
Limit the CPU CFS (Completely Fair Scheduler) quota |
--cpu-rt-period=0 |
Limit the CPU real-time period. In microseconds. Requires parent cgroups be set and cannot be higher than parent. Also check rtprio ulimits. |
--cpu-rt-runtime=0 |
Limit the CPU real-time runtime. In microseconds. Requires parent cgroups be set and cannot be higher than parent. Also check rtprio ulimits. |
--blkio-weight=0 |
Block IO weight (relative weight) accepts a weight value between 10 and 1000. |
--blkio-weight-device="" |
Block IO weight (relative device weight, format: DEVICE_NAME:WEIGHT ) |
--device-read-bps="" |
Limit read rate from a device (format: <device-path>:<number>[<unit>] ). Number is a positive integer. Unit can be one of kb , mb , or gb . |
--device-write-bps="" |
Limit write rate to a device (format: <device-path>:<number>[<unit>] ). Number is a positive integer. Unit can be one of kb , mb , or gb . |
--device-read-iops="" |
Limit read rate (IO per second) from a device (format: <device-path>:<number> ). Number is a positive integer. |
--device-write-iops="" |
Limit write rate (IO per second) to a device (format: <device-path>:<number> ). Number is a positive integer. |
--oom-kill-disable=false |
Whether to disable OOM Killer for the container or not. |
--oom-score-adj=0 |
Tune container’s OOM preferences (-1000 to 1000) |
--memory-swappiness="" |
Tune a container’s memory swappiness behavior. Accepts an integer between 0 and 100. |
--shm-size="" |
Size of /dev/shm . The format is <number><unit> . number must be greater than 0 . Unit is optional and can be b (bytes), k (kilobytes), m (megabytes), or g (gigabytes). If you omit the unit, the system uses bytes. If you omit the size entirely, the system uses 64m . |
User memory constraints
We have four ways to set user memory usage:
| Option | Result |
|---|---|
| memory=inf, memory-swap=inf (default) | There is no memory limit for the container. The container can use as much memory as needed. |
| memory=L<inf, memory-swap=inf | (specify memory and set memory-swap as -1 ) The container is not allowed to use more than L bytes of memory, but can use as much swap as is needed (if the host supports swap memory). |
| memory=L<inf, memory-swap=2*L | (specify memory without memory-swap) The container is not allowed to use more than L bytes of memory, swap plus memory usage is double of that. |
| memory=L<inf, memory-swap=S<inf, L<=S | (specify both memory and memory-swap) The container is not allowed to use more than L bytes of memory, swap plus memory usage is limited by S. |
Examples:
$ docker run -it ubuntu:14.04 /bin/bash
We set nothing about memory, this means the processes in the container can use as much memory and swap memory as they need.
$ docker run -it -m 300M --memory-swap -1 ubuntu:14.04 /bin/bash
We set memory limit and disabled swap memory limit, this means the processes in the container can use 300M memory and as much swap memory as they need (if the host supports swap memory).
$ docker run -it -m 300M ubuntu:14.04 /bin/bash
We set memory limit only, this means the processes in the container can use 300M memory and 300M swap memory, by default, the total virtual memory size (--memory-swap) will be set as double of memory, in this case, memory + swap would be 2*300M, so processes can use 300M swap memory as well.
$ docker run -it -m 300M --memory-swap 1G ubuntu:14.04 /bin/bash
We set both memory and swap memory, so the processes in the container can use 300M memory and 700M swap memory.
Memory reservation is a kind of memory soft limit that allows for greater
sharing of memory. Under normal circumstances, containers can use as much of
the memory as needed and are constrained only by the hard limits set with the
-m
/--memory
option. When memory reservation is set, Docker detects memory
contention or low memory and forces containers to restrict their consumption to
a reservation limit.
Always set the memory reservation value below the hard limit, otherwise the hard limit takes precedence. A reservation of 0 is the same as setting no reservation. By default (without reservation set), memory reservation is the same as the hard memory limit.
Memory reservation is a soft-limit feature and does not guarantee the limit won’t be exceeded. Instead, the feature attempts to ensure that, when memory is heavily contended for, memory is allocated based on the reservation hints/setup.
The following example limits the memory (-m
) to 500M and sets the memory
reservation to 200M.
$ docker run -it -m 500M --memory-reservation 200M ubuntu:14.04 /bin/bash
Under this configuration, when the container consumes memory more than 200M and less than 500M, the next system memory reclaim attempts to shrink container memory below 200M.
The following example set memory reservation to 1G without a hard memory limit.
$ docker run -it --memory-reservation 1G ubuntu:14.04 /bin/bash
The container can use as much memory as it needs. The memory reservation setting ensures the container doesn’t consume too much memory for long time, because every memory reclaim shrinks the container’s consumption to the reservation.
By default, kernel kills processes in a container if an out-of-memory (OOM)
error occurs. To change this behaviour, use the --oom-kill-disable
option.
Only disable the OOM killer on containers where you have also set the
-m/--memory
option. If the -m
flag is not set, this can result in the host
running out of memory and require killing the host’s system processes to free
memory.
The following example limits the memory to 100M and disables the OOM killer for this container:
$ docker run -it -m 100M --oom-kill-disable ubuntu:14.04 /bin/bash
The following example, illustrates a dangerous way to use the flag:
$ docker run -it --oom-kill-disable ubuntu:14.04 /bin/bash
コンテナーのメモリは無制限です。

--oom-score-adj
パラメーターを変更することにより、システム上のメモリ不足時に、どのコンテナーを kill するかの優先度を設定することができます。

カーネルメモリの制約
Kernel memory is fundamentally different than user memory as kernel memory can’t be swapped out. The inability to swap makes it possible for the container to block system services by consuming too much kernel memory. Kernel memory includes：
- stack pages
- slab pages
- sockets memory pressure
- tcp memory pressure
You can setup kernel memory limit to constrain these kinds of memory. For example, every process consumes some stack pages. By limiting kernel memory, you can prevent new processes from being created when the kernel memory usage is too high.
Kernel memory is never completely independent of user memory. Instead, you limit kernel memory in the context of the user memory limit. Assume “U” is the user memory limit and “K” the kernel limit. There are three possible ways to set limits:
| Option | Result |
|---|---|
| U != 0, K = inf (default) | This is the standard memory limitation mechanism already present before using kernel memory. Kernel memory is completely ignored. |
| U != 0, K < U | Kernel memory is a subset of the user memory. This setup is useful in deployments where the total amount of memory per-cgroup is overcommitted. Overcommitting kernel memory limits is definitely not recommended, since the box can still run out of non-reclaimable memory. In this case, you can configure K so that the sum of all groups is never greater than the total memory. Then, freely set U at the expense of the system's service quality. |
| U != 0, K > U | Since kernel memory charges are also fed to the user counter and reclamation is triggered for the container for both kinds of memory. This configuration gives the admin a unified view of memory. It is also useful for people who just want to track kernel memory usage. |
Examples:
$ docker run -it -m 500M --kernel-memory 50M ubuntu:14.04 /bin/bash
We set memory and kernel memory, so the processes in the container can use 500M memory in total, in this 500M memory, it can be 50M kernel memory tops.
$ docker run -it --kernel-memory 50M ubuntu:14.04 /bin/bash
We set kernel memory without -m, so the processes in the container can use as much memory as they want, but they can only use 50M kernel memory.
Swappiness constraint
By default, a container’s kernel can swap out a percentage of anonymous pages.
To set this percentage for a container, specify a --memory-swappiness
value
between 0 and 100. A value of 0 turns off anonymous page swapping. A value of
100 sets all anonymous pages as swappable. By default, if you are not using
--memory-swappiness
, memory swappiness value will be inherited from the parent.
For example, you can set:
$ docker run -it --memory-swappiness=0 ubuntu:14.04 /bin/bash
Setting the --memory-swappiness
option is helpful when you want to retain the
container’s working set and to avoid swapping performance penalties.
CPU share constraint
By default, all containers get the same proportion of CPU cycles. This proportion can be modified by changing the container’s CPU share weighting relative to the weighting of all other running containers.
To modify the proportion from the default of 1024, use the -c
or --cpu-shares
flag to set the weighting to 2 or higher. If 0 is set, the system will ignore the
value and use the default of 1024.
The proportion will only apply when CPU-intensive processes are running. When tasks in one container are idle, other containers can use the left-over CPU time. The actual amount of CPU time will vary depending on the number of containers running on the system.
For example, consider three containers, one has a cpu-share of 1024 and two others have a cpu-share setting of 512. When processes in all three containers attempt to use 100% of CPU, the first container would receive 50% of the total CPU time. If you add a fourth container with a cpu-share of 1024, the first container only gets 33% of the CPU. The remaining containers receive 16.5%, 16.5% and 33% of the CPU.
On a multi-core system, the shares of CPU time are distributed over all CPU cores. Even if a container is limited to less than 100% of CPU time, it can use 100% of each individual CPU core.
For example, consider a system with more than three cores. If you start one
container {C0}
with -c=512
running one process, and another container
{C1}
with -c=1024
running two processes, this can result in the following
division of CPU shares:
PID container CPU CPU share
100 {C0} 0 100% of CPU0
101 {C1} 1 100% of CPU1
102 {C1} 2 100% of CPU2
CPU period constraint
The default CPU CFS (Completely Fair Scheduler) period is 100ms. We can use
--cpu-period
to set the period of CPUs to limit the container’s CPU usage.
And usually --cpu-period
should work with --cpu-quota
.
Examples:
$ docker run -it --cpu-period=50000 --cpu-quota=25000 ubuntu:14.04 /bin/bash
If there is 1 CPU, this means the container can get 50% CPU worth of run-time every 50ms.
In addition to use --cpu-period
and --cpu-quota
for setting CPU period constraints,
it is possible to specify --cpus
with a float number to achieve the same purpose.
For example, if there is 1 CPU, then --cpus=0.5
will achieve the same result as
setting --cpu-period=50000
and --cpu-quota=25000
(50% CPU).
The default value for --cpus
is 0.000
, which means there is no limit.
For more information, see the CFS documentation on bandwidth limiting.
Cpuset constraint
We can set cpus in which to allow execution for containers.
Examples:
$ docker run -it --cpuset-cpus="1,3" ubuntu:14.04 /bin/bash
This means processes in container can be executed on cpu 1 and cpu 3.
$ docker run -it --cpuset-cpus="0-2" ubuntu:14.04 /bin/bash
This means processes in container can be executed on cpu 0, cpu 1 and cpu 2.
We can set mems in which to allow execution for containers. Only effective on NUMA systems.
Examples:
$ docker run -it --cpuset-mems="1,3" ubuntu:14.04 /bin/bash
This example restricts the processes in the container to only use memory from memory nodes 1 and 3.
$ docker run -it --cpuset-mems="0-2" ubuntu:14.04 /bin/bash
This example restricts the processes in the container to only use memory from memory nodes 0, 1 and 2.
CPU quota constraint
The --cpu-quota
flag limits the container’s CPU usage. The default 0 value
allows the container to take 100% of a CPU resource (1 CPU). The CFS (Completely Fair
Scheduler) handles resource allocation for executing processes and is default
Linux Scheduler used by the kernel. Set this value to 50000 to limit the container
to 50% of a CPU resource. For multiple CPUs, adjust the --cpu-quota
as necessary.
For more information, see the CFS documentation on bandwidth limiting.
Block IO bandwidth (Blkio) constraint
By default, all containers get the same proportion of block IO bandwidth
(blkio). This proportion is 500. To modify this proportion, change the
container’s blkio weight relative to the weighting of all other running
containers using the --blkio-weight
flag.
Note: The blkio weight setting is only available for direct IO. Buffered IO is not currently supported.
The --blkio-weight
flag can set the weighting to a value between 10 to 1000.
For example, the commands below create two containers with different blkio
weight:
$ docker run -it --name c1 --blkio-weight 300 ubuntu:14.04 /bin/bash
$ docker run -it --name c2 --blkio-weight 600 ubuntu:14.04 /bin/bash
If you do block IO in the two containers at the same time, by, for example:
$ time dd if=/mnt/zerofile of=test.out bs=1M count=1024 oflag=direct
You’ll find that the proportion of time is the same as the proportion of blkio weights of the two containers.
The --blkio-weight-device="DEVICE_NAME:WEIGHT"
flag sets a specific device weight.
The DEVICE_NAME:WEIGHT
is a string containing a colon-separated device name and weight.
For example, to set /dev/sda
device weight to 200
:
$ docker run -it \
--blkio-weight-device "/dev/sda:200" \
ubuntu
If you specify both the --blkio-weight
and --blkio-weight-device
, Docker
uses the --blkio-weight
as the default weight and uses --blkio-weight-device
to override this default with a new value on a specific device.
The following example uses a default weight of 300
and overrides this default
on /dev/sda
setting that weight to 200
:
$ docker run -it \
--blkio-weight 300 \
--blkio-weight-device "/dev/sda:200" \
ubuntu
The --device-read-bps
flag limits the read rate (bytes per second) from a device.
For example, this command creates a container and limits the read rate to 1mb
per second from /dev/sda
:
$ docker run -it --device-read-bps /dev/sda:1mb ubuntu
The --device-write-bps
flag limits the write rate (bytes per second) to a device.
For example, this command creates a container and limits the write rate to 1mb
per second for /dev/sda
:
$ docker run -it --device-write-bps /dev/sda:1mb ubuntu
Both flags take limits in the <device-path>:<limit>[unit]
format. Both read
and write rates must be a positive integer. You can specify the rate in kb
(kilobytes), mb
(megabytes), or gb
(gigabytes).
The --device-read-iops
flag limits read rate (IO per second) from a device.
For example, this command creates a container and limits the read rate to
1000
IO per second from /dev/sda
:
$ docker run -ti --device-read-iops /dev/sda:1000 ubuntu
The --device-write-iops
flag limits write rate (IO per second) to a device.
For example, this command creates a container and limits the write rate to
1000
IO per second to /dev/sda
:
$ docker run -ti --device-write-iops /dev/sda:1000 ubuntu
Both flags take limits in the <device-path>:<limit>
format. Both read and
write rates must be a positive integer.
Additional groups
--group-add: Add additional groups to run as
By default, the docker container process runs with the supplementary groups looked up for the specified user. If one wants to add more to that list of groups, then one can use this flag:
$ docker run --rm --group-add audio --group-add nogroup --group-add 777 busybox id
uid=0(root) gid=0(root) groups=10(wheel),29(audio),99(nogroup),777
Runtime privilege and Linux capabilities
--cap-add: Add Linux capabilities
--cap-drop: Drop Linux capabilities
--privileged=false: Give extended privileges to this container
--device=[]: Allows you to run devices inside the container without the --privileged flag.
By default, Docker containers are “unprivileged” and cannot, for example, run a Docker daemon inside a Docker container. This is because by default a container is not allowed to access any devices, but a “privileged” container is given access to all devices (see the documentation on cgroups devices).
When the operator executes docker run --privileged
, Docker will enable
access to all devices on the host as well as set some configuration
in AppArmor or SELinux to allow the container nearly all the same access to the
host as processes running outside containers on the host. Additional
information about running with --privileged
is available on the
Docker Blog.
If you want to limit access to a specific device or devices you can use
the --device
flag. It allows you to specify one or more devices that
will be accessible within the container.
$ docker run --device=/dev/snd:/dev/snd ...
By default, the container will be able to read
, write
, and mknod
these devices.
This can be overridden using a third :rwm
set of options to each --device
flag:
$ docker run --device=/dev/sda:/dev/xvdc --rm -it ubuntu fdisk /dev/xvdc
Command (m for help): q
$ docker run --device=/dev/sda:/dev/xvdc:r --rm -it ubuntu fdisk /dev/xvdc
You will not be able to write the partition table.
Command (m for help): q
$ docker run --device=/dev/sda:/dev/xvdc:w --rm -it ubuntu fdisk /dev/xvdc
crash....
$ docker run --device=/dev/sda:/dev/xvdc:m --rm -it ubuntu fdisk /dev/xvdc
fdisk: unable to open /dev/xvdc: Operation not permitted
In addition to --privileged
, the operator can have fine grain control over the
capabilities using --cap-add
and --cap-drop
. By default, Docker has a default
list of capabilities that are kept. The following table lists the Linux capability
options which are allowed by default and can be dropped.
| Capability Key | Capability Description |
|---|---|
| SETPCAP | Modify process capabilities. |
| MKNOD | Create special files using mknod(2). |
| AUDIT_WRITE | Write records to kernel auditing log. |
| CHOWN | Make arbitrary changes to file UIDs and GIDs (see chown(2)). |
| NET_RAW | Use RAW and PACKET sockets. |
| DAC_OVERRIDE | Bypass file read, write, and execute permission checks. |
| FOWNER | Bypass permission checks on operations that normally require the file system UID of the process to match the UID of the file. |
| FSETID | Don’t clear set-user-ID and set-group-ID permission bits when a file is modified. |
| KILL | Bypass permission checks for sending signals. |
| SETGID | Make arbitrary manipulations of process GIDs and supplementary GID list. |
| SETUID | Make arbitrary manipulations of process UIDs. |
| NET_BIND_SERVICE | Bind a socket to internet domain privileged ports (port numbers less than 1024). |
| SYS_CHROOT | Use chroot(2), change root directory. |
| SETFCAP | Set file capabilities. |
The next table shows the capabilities which are not granted by default and may be added.
| Capability Key | Capability Description |
|---|---|
| SYS_MODULE | Load and unload kernel modules. |
| SYS_RAWIO | Perform I/O port operations (iopl(2) and ioperm(2)). |
| SYS_PACCT | Use acct(2), switch process accounting on or off. |
| SYS_ADMIN | Perform a range of system administration operations. |
| SYS_NICE | Raise process nice value (nice(2), setpriority(2)) and change the nice value for arbitrary processes. |
| SYS_RESOURCE | Override resource Limits. |
| SYS_TIME | Set system clock (settimeofday(2), stime(2), adjtimex(2)); set real-time (hardware) clock. |
| SYS_TTY_CONFIG | Use vhangup(2); employ various privileged ioctl(2) operations on virtual terminals. |
| AUDIT_CONTROL | Enable and disable kernel auditing; change auditing filter rules; retrieve auditing status and filtering rules. |
| MAC_ADMIN | Allow MAC configuration or state changes. Implemented for the Smack LSM. |
| MAC_OVERRIDE | Override Mandatory Access Control (MAC). Implemented for the Smack Linux Security Module (LSM). |
| NET_ADMIN | Perform various network-related operations. |
| SYSLOG | Perform privileged syslog(2) operations. |
| DAC_READ_SEARCH | Bypass file read permission checks and directory read and execute permission checks. |
| LINUX_IMMUTABLE | Set the FS_APPEND_FL and FS_IMMUTABLE_FL i-node flags. |
| NET_BROADCAST | Make socket broadcasts, and listen to multicasts. |
| IPC_LOCK | Lock memory (mlock(2), mlockall(2), mmap(2), shmctl(2)). |
| IPC_OWNER | Bypass permission checks for operations on System V IPC objects. |
| SYS_PTRACE | Trace arbitrary processes using ptrace(2). |
| SYS_BOOT | Use reboot(2) and kexec_load(2), reboot and load a new kernel for later execution. |
| LEASE | Establish leases on arbitrary files (see fcntl(2)). |
| WAKE_ALARM | Trigger something that will wake up the system. |
| BLOCK_SUSPEND | Employ features that can block system suspend. |
Further reference information is available on the capabilities(7) - Linux man page
Both flags support the value ALL
, so if the
operator wants to have all capabilities but MKNOD
they could use:
$ docker run --cap-add=ALL --cap-drop=MKNOD ...
For interacting with the network stack, instead of using --privileged
they
should use --cap-add=NET_ADMIN
to modify the network interfaces.
$ docker run -it --rm ubuntu:14.04 ip link add dummy0 type dummy
RTNETLINK answers: Operation not permitted
$ docker run -it --rm --cap-add=NET_ADMIN ubuntu:14.04 ip link add dummy0 type dummy
To mount a FUSE based filesystem, you need to combine both --cap-add
and
--device
:
$ docker run --rm -it --cap-add SYS_ADMIN sshfs sshfs sven@<IP_ADDRESS>:/home/sven /mnt
fuse: failed to open /dev/fuse: Operation not permitted
$ docker run --rm -it --device /dev/fuse sshfs sshfs sven@<IP_ADDRESS>:/home/sven /mnt
fusermount: mount failed: Operation not permitted
$ docker run --rm -it --cap-add SYS_ADMIN --device /dev/fuse sshfs
# sshfs sven@<IP_ADDRESS>:/home/sven /mnt
The authenticity of host '<IP_ADDRESS> (<IP_ADDRESS>)' can't be established.
ECDSA key fingerprint is 25:34:85:75:25:b0:17:46:05:19:04:93:b5:dd:5f:c6.
Are you sure you want to continue connecting (yes/no)? yes
<EMAIL_ADDRESS>password:
root@30aa0cfaf1b5:/# ls -la /mnt/src/docker
total 1516
drwxrwxr-x 1 1000 1000 4096 Dec 4 06:08 .
drwxrwxr-x 1 1000 1000 4096 Dec 4 11:46 ..
-rw-rw-r-- 1 1000 1000 16 Oct 8 00:09 .dockerignore
-rwxrwxr-x 1 1000 1000 464 Oct 8 00:09 .drone.yml
drwxrwxr-x 1 1000 1000 4096 Dec 4 06:11 .git
-rw-rw-r-- 1 1000 1000 461 Dec 4 06:08 .gitignore
....
The default seccomp profile will adjust to the selected capabilities, in order to allow
use of facilities allowed by the capabilities, so you should not have to adjust this,
since Docker 1.12. In Docker 1.10 and 1.11 this did not happen and it may be necessary
to use a custom seccomp profile or use --security-opt seccomp=unconfined
when adding
capabilities.
Logging drivers (--log-driver)
The container can have a different logging driver than the Docker daemon. Use
the --log-driver=VALUE
with the docker run
command to configure the
container’s logging driver. The following options are supported:
| Driver | Description |
|---|---|
none |
Disables any logging for the container. docker logs won’t be available with this driver. |
json-file |
Default logging driver for Docker. Writes JSON messages to file. No logging options are supported for this driver. |
syslog |
Syslog logging driver for Docker. Writes log messages to syslog. |
journald |
Journald logging driver for Docker. Writes log messages to journald . |
gelf |
Graylog Extended Log Format (GELF) logging driver for Docker. Writes log messages to a GELF endpoint likeGraylog or Logstash. |
fluentd |
Fluentd logging driver for Docker. Writes log messages to fluentd (forward input). |
awslogs |
Amazon CloudWatch Logs logging driver for Docker. Writes log messages to Amazon CloudWatch Logs |
splunk |
Splunk logging driver for Docker. Writes log messages to splunk using Event Http Collector. |
The docker logs
command is available only for the json-file
and journald
logging drivers. For detailed information on working with logging drivers, see
Configure logging drivers.
Overriding Dockerfile image defaults
When a developer builds an image from a Dockerfile or when she commits it, the developer can set a number of default parameters that take effect when the image starts up as a container.
Four of the Dockerfile commands cannot be overridden at runtime: FROM
,
MAINTAINER
, RUN
, and ADD
. Everything else has a corresponding override
in docker run
. We’ll go through what the developer might have set in each
Dockerfile instruction and how the operator can override that setting.
- CMD (Default Command or Options)
- ENTRYPOINT (Default Command to Execute at Runtime)
- EXPOSE (Incoming Ports)
- ENV (Environment Variables)
- HEALTHCHECK
- VOLUME (Shared Filesystems)
- USER
- WORKDIR
CMD (default command or options)
Recall the optional COMMAND
in the Docker
commandline:
$ docker run [OPTIONS] IMAGE[:TAG|@DIGEST] [COMMAND] [ARG...]
This command is optional because the person who created the IMAGE
may
have already provided a default COMMAND
using the Dockerfile CMD
instruction. As the operator (the person running a container from the
image), you can override that CMD
instruction just by specifying a new
COMMAND
.
If the image also specifies an ENTRYPOINT
then the CMD
or COMMAND
get appended as arguments to the ENTRYPOINT
.
ENTRYPOINT (default command to execute at runtime)
--entrypoint="": Overwrite the default entrypoint set by the image
The ENTRYPOINT
of an image is similar to a COMMAND
because it
specifies what executable to run when the container starts, but it is
(purposely) more difficult to override. The ENTRYPOINT
gives a
container its default nature or behavior, so that when you set an
ENTRYPOINT
you can run the container as if it were that binary,
complete with default options, and you can pass in more options via the
COMMAND
. But, sometimes an operator may want to run something else
inside the container, so you can override the default ENTRYPOINT
at
runtime by using a string to specify the new ENTRYPOINT
. Here is an
example of how to run a shell in a container that has been set up to
automatically run something else (like /usr/bin/redis-server
):
$ docker run -it --entrypoint /bin/bash example/redis
or two examples of how to pass more parameters to that ENTRYPOINT:
$ docker run -it --entrypoint /bin/bash example/redis -c ls -l
$ docker run -it --entrypoint /usr/bin/redis-cli example/redis --help
You can reset a containers entrypoint by passing an empty string, for example:
$ docker run -it --entrypoint="" mysql bash
Note: Passing
--entrypoint
will clear out any default command set on the image (i.e. anyCMD
instruction in the Dockerfile used to build it).
EXPOSE (incoming ports)
The following run
command options work with container networking:
--expose=[]: Expose a port or a range of ports inside the container.
These are additional to those exposed by the `EXPOSE` instruction
-P : Publish all exposed ports to the host interfaces
-p=[] : Publish a container's port or a range of ports to the host
format: ip:hostPort:containerPort | ip::containerPort | hostPort:containerPort | containerPort
Both hostPort and containerPort can be specified as a
range of ports. When specifying ranges for both, the
number of container ports in the range must match the
number of host ports in the range, for example:
-p 1234-1236:1234-1236/tcp
When specifying a range for hostPort only, the
containerPort must not be a range. In this case the
container port is published somewhere within the
specified hostPort range. (e.g., `-p 1234-1236:1234/tcp`)
(use 'docker port' to see the actual mapping)
--link="" : Add link to another container (<name or id>:alias or <name or id>)
With the exception of the EXPOSE
directive, an image developer hasn’t
got much control over networking. The EXPOSE
instruction defines the
initial incoming ports that provide services. These ports are available
to processes inside the container. An operator can use the --expose
option to add to the exposed ports.
To expose a container’s internal port, an operator can start the
container with the -P
or -p
flag. The exposed port is accessible on
the host and the ports are available to any client that can reach the
host.
The -P
option publishes all the ports to the host interfaces. Docker
binds each exposed port to a random port on the host. The range of
ports are within an ephemeral port range defined by
/proc/sys/net/ipv4/ip_local_port_range
. Use the -p
flag to
explicitly map a single port or range of ports.
The port number inside the container (where the service listens) does
not need to match the port number exposed on the outside of the
container (where clients connect). For example, inside the container an
HTTP service is listening on port 80 (and so the image developer
specifies EXPOSE 80
in the Dockerfile). At runtime, the port might be
bound to 42800 on the host. To find the mapping between the host ports
and the exposed ports, use docker port
.
If the operator uses --link
when starting a new client container in the
default bridge network, then the client container can access the exposed
port via a private networking interface.
If --link
is used when starting a container in a user-defined network as
described in Networking overview,
it will provide a named alias for the container being linked to.
ENV (environment variables)
Docker automatically sets some environment variables when creating a Linux container. Docker does not set any environment variables when creating a Windows container.
The following environment variables are set for Linux containers:
| Variable | Value |
|---|---|
HOME |
Set based on the value of USER |
HOSTNAME |
The hostname associated with the container |
PATH |
Includes popular directories, such as /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin |
TERM |
xterm if the container is allocated a pseudo-TTY |
Additionally, the operator can set any environment variable in the
container by using one or more -e
flags, even overriding those mentioned
above, or already defined by the developer with a Dockerfile ENV
. If the
operator names an environment variable without specifying a value, then the
current value of the named variable is propagated into the container’s environment:
$ export today=Wednesday
$ docker run -e "deep=purple" -e today --rm alpine env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=d2219b854598
deep=purple
today=Wednesday
HOME=/root
PS C:\> docker run --rm -e "foo=bar" microsoft/nanoserver cmd /s /c set
ALLUSERSPROFILE=C:\ProgramData
APPDATA=C:\Users\ContainerAdministrator\AppData\Roaming
CommonProgramFiles=C:\Program Files\Common Files
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
COMPUTERNAME=C2FAEFCC8253
ComSpec=C:\Windows\system32\cmd.exe
foo=bar
LOCALAPPDATA=C:\Users\ContainerAdministrator\AppData\Local
NUMBER_OF_PROCESSORS=8
OS=Windows_NT
Path=C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Users\ContainerAdministrator\AppData\Local\Microsoft\WindowsApps
PATHEXT=.COM;.EXE;.BAT;.CMD
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 62 Stepping 4, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=3e04
ProgramData=C:\ProgramData
ProgramFiles=C:\Program Files
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files
PROMPT=$P$G
PUBLIC=C:\Users\Public
SystemDrive=C:
SystemRoot=C:\Windows
TEMP=C:\Users\ContainerAdministrator\AppData\Local\Temp
TMP=C:\Users\ContainerAdministrator\AppData\Local\Temp
USERDOMAIN=User Manager
USERNAME=ContainerAdministrator
USERPROFILE=C:\Users\ContainerAdministrator
windir=C:\Windows
Similarly the operator can set the HOSTNAME (Linux) or COMPUTERNAME (Windows) with -h
.
HEALTHCHECK
--health-cmd ヘルスチェックを実行するコマンド。
--health-interval ヘルスチェックの実行間隔。
--health-retries 不健康（unhealthy）であると報告するのに必要な連続失敗回数。
--health-timeout 1 つのチェック処理実行に許容する最大時間。
--health-start-period ヘルスチェックのリトライを数え始める前の、コンテナー初期化を行う開始時間。
--no-healthcheck コンテナー固有の HEALTHCHECK を無効にします。
Example:
$ docker run --name=test -d \
--health-cmd='stat /etc/passwd || exit 1' \
--health-interval=2s \
busybox sleep 1d
$ sleep 2; docker inspect --format='{{.State.Health.Status}}' test
healthy
$ docker exec test rm /etc/passwd
$ sleep 2; docker inspect --format='{{json .State.Health}}' test
{
"Status": "unhealthy",
"FailingStreak": 3,
"Log": [
{
"Start": "2016-05-25T17:22:04.635478668Z",
"End": "2016-05-25T17:22:04.7272552Z",
"ExitCode": 0,
"Output": " File: /etc/passwd\n Size: 334 \tBlocks: 8 IO Block: 4096 regular file\nDevice: 32h/50d\tInode: 12 Links: 1\nAccess: (0664/-rw-rw-r--) Uid: ( 0/ root) Gid: ( 0/ root)\nAccess: 2015-12-05 22:05:32.000000000\nModify: 2015..."
},
{
"Start": "2016-05-25T17:22:06.732900633Z",
"End": "2016-05-25T17:22:06.822168935Z",
"ExitCode": 0,
"Output": " File: /etc/passwd\n Size: 334 \tBlocks: 8 IO Block: 4096 regular file\nDevice: 32h/50d\tInode: 12 Links: 1\nAccess: (0664/-rw-rw-r--) Uid: ( 0/ root) Gid: ( 0/ root)\nAccess: 2015-12-05 22:05:32.000000000\nModify: 2015..."
},
{
"Start": "2016-05-25T17:22:08.823956535Z",
"End": "2016-05-25T17:22:08.897359124Z",
"ExitCode": 1,
"Output": "stat: can't stat '/etc/passwd': No such file or directory\n"
},
{
"Start": "2016-05-25T17:22:10.898802931Z",
"End": "2016-05-25T17:22:10.969631866Z",
"ExitCode": 1,
"Output": "stat: can't stat '/etc/passwd': No such file or directory\n"
},
{
"Start": "2016-05-25T17:22:12.971033523Z",
"End": "2016-05-25T17:22:13.082015516Z",
"ExitCode": 1,
"Output": "stat: can't stat '/etc/passwd': No such file or directory\n"
}
]
}
The health status is also displayed in the docker ps
output.
TMPFS (mount tmpfs filesystems)
--tmpfs=[]: Create a tmpfs mount with: container-dir[:<options>],
where the options are identical to the Linux
'mount -t tmpfs -o' command.
The example below mounts an empty tmpfs into the container with the rw
,
noexec
, nosuid
, and size=65536k
options.
$ docker run -d --tmpfs /run:rw,noexec,nosuid,size=65536k my_image
VOLUME (shared filesystems)
-v, --volume=[host-src:]container-dest[:<options>]: Bind mount a volume.
The comma-delimited `options` are [rw|ro], [z|Z],
[[r]shared|[r]slave|[r]private], and [nocopy].
The 'host-src' is an absolute path or a name value.
If neither 'rw' or 'ro' is specified then the volume is mounted in
read-write mode.
The `nocopy` mode is used to disable automatically copying the requested volume
path in the container to the volume storage location.
For named volumes, `copy` is the default mode. Copy modes are not supported
for bind-mounted volumes.
--volumes-from="": Mount all volumes from the given container(s)
Note: When using systemd to manage the Docker daemon’s start and stop, in the systemd unit file there is an option to control mount propagation for the Docker daemon itself, called
MountFlags
. The value of this setting may cause Docker to not see mount propagation changes made on the mount point. For example, if this value isslave
, you may not be able to use theshared
orrshared
propagation on a volume.
The volumes commands are complex enough to have their own documentation
in section Use volumes. A developer can define
one or more VOLUME
’s associated with an image, but only the operator
can give access from one container to another (or from a container to a
volume mounted on the host).
The container-dest
must always be an absolute path such as /src/docs
.
The host-src
can either be an absolute path or a name
value. If you
supply an absolute path for the host-dir
, Docker bind-mounts to the path
you specify. If you supply a name
, Docker creates a named volume by that name
.
A name
value must start with an alphanumeric character,
followed by a-z0-9
, _
(underscore), .
(period) or -
(hyphen).
An absolute path starts with a /
(forward slash).
For example, you can specify either /foo
or foo
for a host-src
value.
If you supply the /foo
value, Docker creates a bind mount. If you supply
the foo
specification, Docker creates a named volume.
USER
root
(id = 0) is the default user within a container. The image developer can
create additional users. Those users are accessible by name. When passing a numeric
ID, the user does not have to exist in the container.
The developer can set a default user to run the first process with the
Dockerfile USER
instruction. When starting a container, the operator can override
the USER
instruction by passing the -u
option.
-u="", --user="": Sets the username or UID used and optionally the groupname or GID for the specified command.
The followings examples are all valid:
--user=[ user | user:group | uid | uid:gid | user:gid | uid:group ]
Note: if you pass a numeric uid, it must be in the range of 0-2147483647.
WORKDIR
The default working directory for running binaries within a container is the
root directory (/
), but the developer can set a different default with the
Dockerfile WORKDIR
command. The operator can override this with:
-w="": Working directory inside the container


Refugees, Men, Women, Children, Education, Hope, Play, Shelter, Sanitation, Health, Border, Elderly
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
LEBANON
JORDAN
JORDAN
LEBANON
LEBANON
We at UNHCR gravely fear for the safety people trapped and attempting to flee Qusayr, a besieged town in Syria. My colleagues in Lebanon spoke to several refugees who had managed to escape there, many arriving in the town of Arsal in the Bekaa valley. They spoke of an extremely difficult journey, made on foot. They said that fighters were targeting people as they attempt to flee. No route out of Qusayr is considered safe, and there are reports that between 700 and 1500 injured civilians are trapped in the city. They say it is particularly perilous to flee with men, who are at heightened risk of being arrested or killed at checkpoints along the way. None of the refugees was able or willing to identify those who are manning the checkpoints. From one woman, we heard that people in Qusayr are faced with a stark choice: "you leave and risking being killed by a bomb, or you stay and facing a certainty of being killed."...READ MORE
UN High Commissioner for Refugees António Guterres today welcomed the European Union's announcement of a major new contribution of up to €400 million for the Syria situation until the end of the year. The funding announced by the EU is among the largest so far to the Syria crisis by any donor. The €400 million is expected to go towards the regional refugee response as well as humanitarian needs inside Syria. UNHCR understands that €150 million is allotted for development-related aid that includes support to communities hosting refugees and security for refugee camps...READ MORE
There is a part of Ahmed that doesn't miss the prosperity and possessions that he left behind, including his library of law books and the volumes of poetry that he read during evenings of leisure. He does not regret folding up a lucrative criminal law practice in the western Syrian city of Hama before escaping the hell of Syria's conflict. The 34-year-old left Syria early morning last August 28 and fled to Lebanon. The final straw was when his mother, worried about his safety, broke down in tears and begged him to leave. This was a few days after Ahmed's home was obliterated by artillery shells and then set on fire. But, despite the death, detentions and violence, Ahmed still lives. He has his health and strength, and his wife and their baby daughter, who is nearly two months old now...READ MORE
The UN refugee agency on Tuesday said it has been seeing small numbers of refugees arriving in eastern Lebanon after escaping from the embattled Syrian town of Al Qusayr, where heavy fighting flared up three weeks ago. The refugees, mostly women and children, have told UNHCR staff that the strategically located town in western Syria has been badly damaged and the living conditions are extremely difficult. They said the route to Lebanon was dangerous and it was unsafe to travel with men. "From the handful of interviews we have done so far, it appears that a new route for displaced people has opened up from the Qusayr area towards Arsal in Lebanon, about 100 kilometres away," UNHCR spokesperson Melissa Fleming told journalists in Geneva. "Some of those forced out of Qusayr by the fighting are fleeing into Lebanon as refugees, while others are being displaced internally to towns, including Rankous, Dahel, Qara, Flita and Nabek," she added...READ MORE
As growing numbers of Syrians leave their country, the UN refugee agency continues to deliver aid to desperate Syrians inside the country amid difficult operational and security challenges. During a week when the number of Syrian refugees in neighbouring countries passed the 1.6 million mark, UNHCR on Wednesday joined an inter-agency mission guided by the Syrian Arab Red Crescent to assess the situation and needs of internally displaced families in Hasiya, a town of 16,000 in central-western Syria. "UNHCR was able to witness the dire humanitarian situation of these displaced families," spokesman Dan McNorton told journalists in Geneva, adding that the families hailed from Al Qusayr, some 25 kilometres away...READ MORE
Abdul, a 37-year-old refugee from the northern Syria city of Aleppo, navigates the hardscrabble streets of Amman's Al Ashrafyeh district with watchful suspicion. The slightly built father of four children, one of whom is sick, is careful not to spend too much time on the street. When he goes outside, he keeps to himself. "I don't interfere with anyone in this neighbourhood," he says. "I don't say anything. I don't deal with them." There is a clear tension in Al Ashrafyeh, where Syrian families have arrived in search of shelter over the months. This refugee community is far from wealthy and there are concerns about the burden they may represent...READ MORE
visit http://storify.com/unhcrmedia to see the latest roundup of syria/unhcr coverage in the news
Ahmad, who fled #Qusair recently, asked to paint picture of home: 'I give you a blank page. Nothing is left standing' #Syria
Meanwhile, in #Turkey, there are now 400,000 Syrian refugees. 75% are women and kids. pic.twitter.com/vL5wqvqPJI
Starting to receive @refugees from Al Qusayr #Syria. According to new arrivals it took 15 days from fleeing the fighting to reach #jordan
Correction: #Zaatari camp is in fact the 5th largest city in #Jordan hosting some 120,000 #Syrian refugees. pic.twitter.com/5RmpvPoaQq
If you share 1 thing today, make it Dounia (the world) & baby Ahmed's story http://rfg.ee/lC6Jl @SybellaWilkes @guardianwitness #Syria
Ali's father begged me to take a #photo of his son to show the world how innocent people are dying in #Syria #Qusair pic.twitter.com/AtX8xGDvBv
< UNHCR SOCIAL MEDIA


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Clean Up This Black Friday With Deals on Shark Vacuums
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Keep up to speed with with all of the deals that are dropping in the run up to Black Friday over on our deals hub.


P-A
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>From Mr.Abu M.Sesay I Need Your Assistance Please. Dear Friend, Through the courtesy of business opportunit, i take liberty anchored on a strong desire to solicit your assistance on this mutually beneficial and riskfree transaction which i hope you will give your urgent attention. I am Mr.Abu M.Sesay i am moved to write you this letter,this was incinfidence considration, our present circumstances and situation, i escaped with my wife and children out of Sierrial Leone to Ghana where we are presently residing on temporary political asylum. However, due to this situation i decided to change most of my Billions of Dollars deposited in Swiss Bank and other countries into other forms of money coded for safe purpose because the new head of state Ahmed Tijjan Kabba made arrangement with the Swiss Goverment and other European countries to freeze all my treasures deposited in some european countries, hence i and my family, decided laying low in Africa to study the situation till when things gets better, since president Tijjan Kabba taking over goverment again in Sierria Leone. One of my chateaux in Southern France was confiscated by the French Goverment, and as such we had to change our identity so thet our investment will not be trace and confiscated. I have deposited the sum of Thirty Million,Five Hundred Thousand United States Dollars{US$30,500,000} with a security company for safekeeping. The funds are security coded to prevent them from knowing the actual content . What i want you to do now is to indicate your inetrest that you will assist me and my immediate family by receiving the money my behalf. The Account required for this project can be personal, company or an offshore account that you have been total control over, your area of specialisation will not be a hinderance to the successful execution of this transaction. Ackowledge this message, so that i can introduce you to my family as our foreign trusted partner who shall take charge of our investment abroad where we now plan to settle. I want you to assist us in investing this fund or money, but i will not want our identity revealed. I will also want to buy properties and stocks in multy- national companies and to engage in other safe and non speculative investments. We have been through a lot of health and spiritual turmoil, hence will need your understanding and assistance and may i at this junction emphasize the high level of confidentiality which this business demands and hope you will not betral the trust and confidence which we repose in you. shall put you in the picture of this buiness, i.e tell you where the funds are currently being maintained and also discuss other modalities including remuneration for your services. I shall also inform you with the next line of action as soon as i receive your response. Finaly if this preposition is attainable, Please kindly funish me immediately by E-mail with your direct telephone number and fax number to enhance the confidentiality which this business demands. Best Regards, Mr.Abu M.Sesay ___________________________________________________________________ Buy gifts for all occasions online from http://shop.di-ve.com


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java.lang.Object com.hoodcomputing.natpmp.NatPmpDevice
public class NatPmpDevice
This class manages a NAT-PMP device. This class is thread-safe.
This manages communication with a NAT-PMP device on the network. There are
two types of messages that can be sent to the device.
ExternalAddressRequestMessage
can be sent to get the external IP of
the gateway. MapRequestMessage
can be sent to map a port for a
certain amount of time. These two messages can be put into the message queue
through the enqueueMessage(Message)
method.
As this class manages a message queue to the NAT-PMP device, it is important
to shut it down corectly. Any mapped ports that are no longer desired should
be unmapped before shutdown occurs. Refer to NatPmpDevice(boolean)
for details about the shutdown mechanism.
| Constructor Summary | |
|---|---|
NatPmpDevice(boolean shutdownHookEnabled)
Constructs a new NatPmpDevice. |
| Method Summary | |
|---|---|
void |
clearQueue()
Clears the queue of messages to send. |
void |
enqueueMessage(Message message)
Enqueues a message for sending. |
boolean |
isShutdown()
Flag indicates if this NatPmpDevice is shutdown. |
boolean |
isShutdownHookEnabled()
Flag indicates if the shutdown hook is enabled or disabled. |
void |
setShutdownHookEnabled(boolean enabled)
Sets the enabled state of the shutdown hook functionality of this object. |
void |
shutdown()
Shuts down this NatPmpDevice. |
java.lang.Thread |
shutdownAsync(boolean daemon)
This method creates and runs a thread for the shutdown() method. |
void |
waitUntilQueueEmpty()
Synchronously waits until the queue is empty before returning. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public NatPmpDevice(boolean shutdownHookEnabled) throws NatPmpException
shutdownHookEnabled
- Shutting down existing port mappings is a
desired behavior; therefore, this value is required! Refer to
setShutdownHookEnabled(boolean)
for details about what value
should be provided here and how it alters the object's behavior.
NatPmpException
- A NatPmpException may be thrown if the local
network is not using addresses defined in RFC1918. A NatPmpException may
also be thrown if the the network gateway cannot be determined, which may
rarely be due to the network not using IPv4. NAT-PMP should only be used
on RFC1918 networks using IPv4.setShutdownHookEnabled(boolean)
,
shutdown()
| Method Detail |
|---|
public void enqueueMessage(Message message)
message
- The Message
to send.clearQueue()
public void clearQueue()
enqueueMessage(Message)
public void waitUntilQueueEmpty()
public final boolean isShutdownHookEnabled()
setShutdownHookEnabled(boolean)
,
shutdown()
public final void setShutdownHookEnabled(boolean enabled)
enabled
- If true is specified, the NatPmpDevice will hook into the
shutdown of the Java VM. When the VM is shutting down, this object will
attempt to remove the port mappings. The procedure may silently fail, in
which case, the timeout on the port map will eventually occur. If false
is specified, it is up to the consumer of the object to call
shutdown()
when the device needs to be disregarded. If shutdown
is called when true is specified here, the hook will be automatically
removed.isShutdownHookEnabled()
,
shutdown()
public void shutdown()
shutdownAsync(boolean)
method should be called.
isShutdown()
,
isShutdownHookEnabled()
,
setShutdownHookEnabled(boolean)
,
shutdownAsync(boolean)
public java.lang.Thread shutdownAsync(boolean daemon)
shutdown()
method.
If the shutdown hook is enabled, it is disabled automatically.
daemon
- Run the thread as a daemon. The Java VM will not wait
for the thread to complete when it is shutting down.
Thread
that was created and started. This return
value is useful is you would like to monitor the thread.shutdown()
,
isShutdown()
public boolean isShutdown()
Thread
instead.
shutdown()
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Digging further into housing dynamics and trends, Stabilization gives users a better sense of a neighborhood’s housing stability by providing data on occupancy, density, and transfers. Inversely, we can also learn more about areas of destabilized housing that may need to be flagged for attention due to foreclosure filings, sheriff’s sales, and/or other indicators of distress.
| Indicator | % change | |
|---|---|---|
| Indicator | % change | |
|---|---|---|
Sources: Cuyahoga County Fiscal Office, Cuyahoga County Clerk of Courts, Cuyahoga County Sheriff's Department, HUD / USPS.


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Spread information about the free and open source movement as well as FOSS projects
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Homeserve posts higher revenue as it eyes US expansion
by Joe CurtisEmergency repairs business Homeserve saw revenue jump 13 per cent in its latest half-year results.
That led it to hike its interim dividend as it announced a $140m deal for a controlling stake in US firm eLocal, as it boosts its presence across the pond.
Read more: Shareholders rebel at Homeserve over ex-director payouts
The figures
Revenue rose 13 per cent year on year to hit £457.7m in the six months to the end of September.
Profit before tax inched up two per cent to £19.7m while basic earnings per share climbed nine per cent to 5p.
Operating profit increased 17 per cent to £70.9m.
That came despite a one per cent decline in customer numbers to 8.2m.
Net debt rose 55 per cent year on year to £451.4m after new accounting rules forced Homeserve to recognise lease liabilities on its balance sheet.
Homeserve raised its interim dividend 12 per cent to 5.8p per share.
Read more: Homeserve maintains strong outlook after robust US performance
Why it’s interesting
Homeserve cited a strong performance in its membership businesses, such as heating, ventilation and air conditioning services.
It saw strong profit growth in the US, where customer numbers have hit 4.2m, as well as the UK, where operating profit rose 38 per cent to £14m, over its half-year.
Revenue from trade review site Checkatrade also grew 34 per cent, with a 28 per cent jump in website visitors to 11.5m.
The firm also agreed to buy 79 per cent of eLocal for around $140m as a way to expand its presence in the US.
Homeserve has also appointed a new senior independent director in Katrina Cliffe to replace outgoing non-executive director Stella David.
Cliffe is currently a non-executive director of Cembra Money Bank, London and Country Mortgages Limited and Majestic Wine.
What Homeserve said
Richard Harpin, founder and group chief executive, said:
I am very pleased with our financial performance and strategic progress in the first half of this year. All of our Membership businesses performed well, with North America continuing to deliver strong growth, and interesting opportunities in all our European businesses to develop new partnerships, harness new technology and continue to improve customer service and efficiency. Our buy-and-build approach to HVAC added five profitable new acquisitions and will become a significant business line for us for the first time this year. In Home Experts, we have another business line with global appeal. Checkatrade and Habitissimo are both market leaders and in eLocal, we have agreed to acquire a majority stake in a high growth business which gives us a profitable entry into Home Experts in North America.