run

Modified: 18 Aug 2016 16:34 UTC
Stability: Unknown

Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

Run a command in a new container

  -a, --attach=[]                  Attach to STDIN, STDOUT or STDERR
  --add-host=[]                    Add a custom host-to-IP mapping (host:ip)
  --blkio-weight=0                 Block IO weight (relative weight)
  -c, --cpu-shares=0               CPU shares (relative weight)
  --cap-add=[]                     Add Linux capabilities
  --cap-drop=[]                    Drop Linux capabilities
  --cgroup-parent=""               Optional parent cgroup for the container
  --cidfile=""                     Write the container ID to the file
  --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)
  --cpu-period=0                   Limit the CPU CFS (Completely Fair Scheduler) period
  --cpu-quota=0                    Limit the CPU CFS (Completely Fair Scheduler) quota
  -d, --detach=false               Run container in background and print container ID
  --detach-keys                    Override the key sequence for detaching a container
  --device=[]                      Add a host device to the container
  --device-read-bps=[]             Limit read rate (bytes per second) from a device
  --device-read-iops=[]            Limit read rate (IO per second) from a device
  --device-write-bps=[]            Limit write rate (bytes per second) to a device
  --device-write-iops=[]           Limit write rate (IO per second) to a device
  --disable-content-trust=true     Skip image verification
  --dns=[]                         Set custom DNS servers
  --dns-opt=[]                     Set DNS options
  --dns-search=[]                  Set custom DNS search domains
  -e, --env=[]                     Set environment variables
  --entrypoint=""                  Overwrite the default ENTRYPOINT of the image
  --env-file=[]                    Read in a file of environment variables
  --expose=[]                      Expose a port or a range of ports
  -h, --hostname=""                Container host name
  --help=false                     Print usage
  -i, --interactive=false          Keep STDIN open even if not attached
  --ip                             Container IPv4 address (e.g. 172.30.100.104)
  --ip6                            Container IPv6 address (e.g. 2001:db8::33)
  --ipc=""                         IPC namespace to use
  --isolation                      Container isolation level
  --kernel-memory                  Kernel memory limit
  --link=[]                        Add link to another container
  --log-driver=""                  Logging driver for container
  --log-opt=[]                     Log driver specific options
  -l, --label=[]                   Set metadata on the container (e.g., --label=com.example.key=value)
  --label-file=[]                  Read in a file of labels (EOL delimited)
  -m, --memory=""                  Memory limit
  --mac-address=""                 Container MAC address (e.g. 92:d0:c6:0a:29:33)
  --memory-reservation             Memory soft limit
  --memory-swap=""                 Total memory (memory + swap), '-1' to disable swap
  --memory-swappiness=""           Tune container memory swappiness (0 to 100)
  --name=""                        Assign a name to the container
  --network=default                Connect a container to a network
  --network-alias=[]               Add network-scoped alias for the container
  --oom-kill-disable=false         Whether to disable OOM Killer for the container or not
  --oom-score-adj                  Tune host's OOM preferences (-1000 to 1000)
  -P, --publish-all=false          Publish all exposed ports to random ports
  -p, --publish=[]                 Publish a container's port(s) to the host
  --pid=""                         PID namespace to use
  --privileged=false               Give extended privileges to this container
  --read-only=false                Mount the container's root filesystem as read only
  --restart="no"                   Restart policy (no, on-failure[:max-retry], always)
  --rm=false                       Automatically remove the container when it exits
  --security-opt=[]                Security Options
  --shm-size                       Size of /dev/shm, default value is 64MB
  --sig-proxy=true                 Proxy received signals to the process
  --stop-signal=SIGTERM            Signal to stop a container, SIGTERM by default
  -t, --tty=false                  Allocate a pseudo-TTY
  --tmpfs=[]                       Mount a tmpfs directory
  -u, --user=""                    Username or UID (format: <name|uid>[:<group|gid>])
  --ulimit=[]                      Ulimit options
  --uts=""                         UTS namespace to use
  -v, --volume=[]                  Bind mount a volume
  --volume-driver                  Optional volume driver for the container
  --volumes-from=[]                Mount volumes from the specified container(s)
  -w, --workdir=""                 Working directory inside the container

The docker run command first creates a writeable container layer over the specified image, and then starts it using the specified command. That is, docker run is equivalent to the API /containers/create then /containers/(id)/start. A stopped container can be restarted with all its previous changes intact using docker start. See docker ps -a to view a list of all containers.

There is detailed information about docker run in the Docker run reference.

The docker run command can be used in combination with docker commit to change the command that a container runs.

See the Docker User Guide for more detailed information about the --expose, -p, -P and --link parameters, and linking containers.

Examples

$ docker run --name test -it debian
$$ exit 13
exit
$ echo $?
13
$ docker ps -a | grep test
275c44472aeb        debian:7            "/bin/bash"         26 seconds ago      Exited (13) 17 seconds ago                         test

In this example, we are running bash interactively in the debian:latest image, and giving the container the name test. We then quit bash by running exit 13, which means bash will have an exit code of 13. This is then passed on to the caller of docker run, and is recorded in the test container metadata.

$ docker run --cidfile /tmp/docker_test.cid ubuntu echo "test"

This will create a container and print test to the console. The cidfile flag makes Docker attempt to create a new file and write the container ID to it. If the file exists already, Docker will return an error. Docker will close this file when docker run exits.

$ docker run -t -i --rm ubuntu bash
root@bc338942ef20:/# mount -t tmpfs none /mnt
mount: permission denied

This will not work, because by default, most potentially dangerous kernel capabilities are dropped; including cap_sys_admin (which is required to mount filesystems). However, the --privileged flag will allow it to run:

$ docker run --privileged ubuntu bash
root@50e3f57e16e6:/# mount -t tmpfs none /mnt
root@50e3f57e16e6:/# df -h
Filesystem      Size  Used Avail Use% Mounted on
none            1.9G     0  1.9G   0% /mnt

The --privileged flag gives all capabilities to the container, and it also lifts all the limitations enforced by the device cgroup controller. In other words, the container can then do almost everything that the host can do. This flag exists to allow special use-cases, like running Docker within Docker.

$ docker  run -w /path/to/dir/ -i -t  ubuntu pwd

The -w lets the command being executed inside directory given, here /path/to/dir/. If the path does not exists it is created inside the container.

$ docker  run  -v `pwd`:`pwd` -w `pwd` -i -t  ubuntu pwd

The -v flag mounts the current working directory into the container. The -w lets the command being executed inside the current working directory, by changing into the directory to the value returned by pwd. So this combination executes the command using the container, but inside the current working directory.

$ docker run -v /doesnt/exist:/foo -w /foo -i -t ubuntu bash

When the host directory of a bind-mounted volume doesn't exist, Docker will automatically create this directory on the host for you. In the example above, Docker will create the /doesnt/exist folder before starting your container.

$ docker run --read-only -v /icanwrite busybox touch /icanwrite here

Volumes can be used in combination with --read-only to control where a container writes files. The --read-only flag mounts the container's root filesystem as read only prohibiting writes to locations other than the specified volumes for the container.

$ docker run -t -i -v /var/run/docker.sock:/var/run/docker.sock -v ./static-docker:/usr/bin/docker busybox sh

By bind-mounting the docker unix socket and statically linked docker binary (such as that provided by https://get.docker.com), you give the container the full access to create and manipulate the host's Docker daemon.

$ docker run -p 127.0.0.1:80:8080 ubuntu bash

This binds port 8080 of the container to port 80 on 127.0.0.1 of the host machine. The Docker User Guide explains in detail how to manipulate ports in Docker.

$ docker run --expose 80 ubuntu bash

This exposes port 80 of the container for use within a link without publishing the port to the host system's interfaces. The Docker User Guide explains in detail how to manipulate ports in Docker.

$ docker run -e MYVAR1 --env MYVAR2=foo --env-file ./env.list ubuntu bash

This sets environmental variables in the container. For illustration all three flags are shown here. Where -e, --env take an environment variable and value, or if no = is provided, then that variable's current value is passed through (i.e. $MYVAR1 from the host is set to $MYVAR1 in the container). When no = is provided and that variable is not defined in the client's environment then that variable will be removed from the container's list of environment variables. All three flags, -e, --env and --env-file can be repeated.

Regardless of the order of these three flags, the --env-file are processed first, and then -e, --env flags. This way, the -e or --env will override variables as needed.

$ cat ./env.list
TEST_FOO=BAR
$ docker run --env TEST_FOO="This is a test" --env-file ./env.list busybox env | grep TEST_FOO
TEST_FOO=This is a test

The --env-file flag takes a filename as an argument and expects each line to be in the VAR=VAL format, mimicking the argument passed to --env. Comment lines need only be prefixed with #

An example of a file passed with --env-file

$ cat ./env.list
TEST_FOO=BAR

# this is a comment
TEST_APP_DEST_HOST=10.10.0.127
TEST_APP_DEST_PORT=8888

# pass through this variable from the caller
TEST_PASSTHROUGH
$ sudo TEST_PASSTHROUGH=howdy docker run --env-file ./env.list busybox env
HOME=/
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=5198e0745561
TEST_FOO=BAR
TEST_APP_DEST_HOST=10.10.0.127
TEST_APP_DEST_PORT=8888
TEST_PASSTHROUGH=howdy

$ docker run --name console -t -i ubuntu bash

A label is a a key=value pair that applies metadata to a container. To label a container with two labels:

$ docker run -l my-label --label com.example.foo=bar ubuntu bash

The my-label key doesn't specify a value so the label defaults to an empty string(""). To add multiple labels, repeat the label flag (-l or --label).

The key=value must be unique to avoid overwriting the label value. If you specify labels with identical keys but different values, each subsequent value overwrites the previous. Docker uses the last key=value you supply.

Use the --label-file flag to load multiple labels from a file. Delimit each label in the file with an EOL mark. The example below loads labels from a labels file in the current directory:

$ docker run --label-file ./labels ubuntu bash

The label-file format is similar to the format for loading environment variables. (Unlike environment variables, labels are not visible to processes running inside a container.) The following example illustrates a label-file format:

com.example.label1="a label"

# this is a comment
com.example.label2=another\ label
com.example.label3

You can load multiple label-files by supplying multiple --label-file flags.

For additional information on working with labels, see Labels - custom metadata in Docker in the Docker User Guide.

$ docker run --link /redis:redis --name console ubuntu bash

The --link flag will link the container named /redis into the newly created container with the alias redis. The new container can access the network and environment of the redis container via environment variables. The --name flag will assign the name console to the newly created container.

$ docker run --volumes-from 777f7dc92da7 --volumes-from ba8c0c54f0f2:ro -i -t ubuntu pwd

The --volumes-from flag mounts all the defined volumes from the referenced containers. Containers can be specified by repetitions of the --volumes-from argument. The container ID may be optionally suffixed with :ro or :rw to mount the volumes in read-only or read-write mode, respectively. By default, the volumes are mounted in the same mode (read write or read only) as the reference container.

The -a flag tells docker run to bind to the container's STDIN, STDOUT or STDERR. This makes it possible to manipulate the output and input as needed.

$ echo "test" | docker run -i -a stdin ubuntu cat -

This pipes data into a container and prints the container's ID by attaching only to the container's STDIN.

$ docker run -a stderr ubuntu echo test

This isn't going to print anything unless there's an error because we've only attached to the STDERR of the container. The container's logs still store what's been written to STDERR and STDOUT.

$ cat somefile | docker run -i -a stdin mybuilder dobuild

This is how piping a file into a container could be done for a build. The container's ID will be printed after the build is done and the build logs could be retrieved using docker logs. This is useful if you need to pipe a file or something else into a container and retrieve the container's ID once the container has finished running.

$ docker run --device=/dev/sdc:/dev/xvdc --device=/dev/sdd --device=/dev/zero:/dev/nulo -i -t ubuntu ls -l /dev/{xvdc,sdd,nulo} brw-rw---- 1 root disk 8, 2 Feb 9 16:05 /dev/xvdc brw-rw---- 1 root disk 8, 3 Feb 9 16:05 /dev/sdd crw-rw-rw- 1 root root 1, 5 Feb 9 16:05 /dev/nulo

It is often necessary to directly expose devices to a container. The --device option enables that. For example, a specific block storage device or loop device or audio device can be added to an otherwise unprivileged container (without the --privileged flag) and have the application directly access it.

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 --rm -it ubuntu fdisk  /dev/xvdc

    Command (m for help): q

    $ docker run --device=/dev/sda:/dev/xvdc:m --rm -it ubuntu fdisk  /dev/xvdc
    fdisk: unable to open /dev/xvdc: Operation not permitted

Note: --device cannot be safely used with ephemeral devices. Block devices that may be removed should not be added to untrusted containers with --device.

A complete example:

$ docker run -d --name static static-web-files sh
$ docker run -d --expose=8098 --name riak riakserver
$ docker run -d -m 100m -e DEVELOPMENT=1 -e BRANCH=example-code -v $(pwd):/app/bin:ro --name app appserver
$ docker run -d -p 1443:443 --dns=10.0.0.1 --dns-search=dev.org -v /var/log/httpd --volumes-from static --link riak --link app -h www.sven.dev.org --name web webserver
$ docker run -t -i --rm --volumes-from web -w /var/log/httpd busybox tail -f access.log

This example shows five containers that might be set up to test a web application change:

  1. Start a pre-prepared volume image static-web-files (in the background) that has CSS, image and static HTML in it, (with a VOLUME instruction in the Dockerfile to allow the web server to use those files);
  2. Start a pre-prepared riakserver image, give the container name riak and expose port 8098 to any containers that link to it;
  3. Start the appserver image, restricting its memory usage to 100MB, setting two environment variables DEVELOPMENT and BRANCH and bind-mounting the current directory ($(pwd)) in the container in read-only mode as /app/bin;
  4. Start the webserver, mapping port 443 in the container to port 1443 on the Docker server, setting the DNS server to 10.0.0.1 and DNS search domain to dev.org, creating a volume to put the log files into (so we can access it from another container), then importing the files from the volume exposed by the static container, and linking to all exposed ports from riak and app. Lastly, we set the hostname to web.sven.dev.org so its consistent with the pre-generated SSL certificate;
  5. Finally, we create a container that runs tail -f access.log using the logs volume from the web container, setting the workdir to /var/log/httpd. The --rm option means that when the container exits, the container's layer is removed.

Restart policies

Use Docker's --restart to specify a container's restart policy. A restart policy controls whether the Docker daemon restarts a container after exit. Docker supports the following restart policies:

Policy 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.
$ 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.

More detailed information on restart policies can be found in the Restart Policies (--restart) section of the Docker run reference page.

Adding entries to a container hosts file

You can add other hosts into a container's /etc/hosts file by using one or more --add-host flags. This example adds a static address for a host named docker:

    $ docker run --add-host=docker:10.180.0.1 --rm -it debian
    $$ ping docker
    PING docker (10.180.0.1): 48 data bytes
    56 bytes from 10.180.0.1: icmp_seq=0 ttl=254 time=7.600 ms
    56 bytes from 10.180.0.1: icmp_seq=1 ttl=254 time=30.705 ms
    ^C--- docker ping statistics ---
    2 packets transmitted, 2 packets received, 0% packet loss
    round-trip min/avg/max/stddev = 7.600/19.152/30.705/11.553 ms

Sometimes you need to connect to the Docker host from within your container. To enable this, pass the Docker host's IP address to the container using the --add-host flag. To find the host's address, use the ip addr show command.

The flags you pass to ip addr show depend on whether you are using IPv4 or IPv6 networking in your containers. Use the following flags for IPv4 address retrieval for a network device named eth0:

$ HOSTIP=`ip -4 addr show scope global dev eth0 | grep inet | awk '{print \$2}' | cut -d / -f 1`
$ docker run  --add-host=docker:${HOSTIP} --rm -it debian

For IPv6 use the -6 flag instead of the -4 flag. For other network devices, replace eth0 with the correct device name (for example docker0 for the bridge device).

Setting ulimits in a container

Since setting ulimit settings in a container requires extra privileges not available in the default container, you can set these using the --ulimit flag. --ulimit is specified with a soft and hard limit as such: <type>=<soft limit>[:<hard limit>], for example:

    $ docker run --ulimit nofile=1024:1024 --rm debian ulimit -n
    1024

Note: If you do not provide a hard limit, the soft limit will be used for both values. If no ulimits are set, they will be inherited from the default ulimits set on the daemon. as option is disabled now. In other words, the following script is not supported: $ docker run -it --ulimit as=1024 fedora /bin/bash

Divergence

Triton's secure, multi-tenant, container-native environment imposes some differences from Docker Inc's implementation. Notably, arguments to control LXC or change container privilege are unsupported. Other arguments, such as those to manage CPU allocation, or networking, are more effective because of features unique to Triton. See the Resources and Networks documentation for more information on how to size containers and assign public or private IP addresses to them.

Docker Swarm's affinity filters for controlling on which server a container is provisioned are supported. See the placement feature documentation for details.