# run 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 --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 --device=[] Add a host device to the container --dns=[] Set custom DNS servers --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 --ipc="" IPC namespace to use --link=[] Add link to another container --log-driver="" Logging driver for container --log-opt=[] Log driver specific options --lxc-conf=[] Add custom lxc options -m, --memory="" Memory limit -l, --label=[] Set metadata on the container (e.g., --label=com.example.key=value) --label-file=[] Read in a file of labels (EOL delimited) --mac-address="" Container MAC address (e.g. 92:d0:c6:0a:29:33) --memory-swap="" Total memory (memory + swap), '-1' to disable swap --name="" Assign a name to the container --net="bridge" Set the Network mode for the container --oom-kill-disable=false Whether to disable OOM Killer for the container or not -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 --uts="" UTS 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 --sig-proxy=true Proxy received signals to the process -t, --tty=false Allocate a pseudo-TTY -u, --user="" Username or UID (format: [:]) -v, --volume=[] Bind mount a volume --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]( /reference/run/). The `docker run` command can be used in combination with `docker commit` to [*change the command that a container runs*](#commit-an-existing-container). See the [Docker User Guide](/userguide/dockerlinks/) for more detailed information about the `--expose`, `-p`, `-P` and `--link` parameters, and linking containers. ## Examples $ docker run --name test -it debian root@d6c0fe130dba:/# exit 13 $ echo $? 13 $ docker ps -a | grep test d6c0fe130dba debian:7 "/bin/bash" 26 seconds ago Exited (13) 17 seconds ago test This example runs a container named `test` using the `debian:latest` image. The `-it` instructs Docker to allocate a pseudo-TTY connected to the container's stdin; creating an interactive `bash` shell in the container. In the example, the `bash` shell is quit by entering `exit 13`. This exit code is passed on to the caller of `docker run`, and is recorded in the `test` container's 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]( 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](/userguide/dockerlinks/) 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](/userguide/dockerlinks) 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*](/userguide/labels-custom-metadata/) 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 `--link` flag will also just accept the form `` in which case the alias will match the name. For instance, you could have written the previous example as: $ docker run --link redis --name console ubuntu bash 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. Labeling systems like SELinux require that proper labels are placed on volume content mounted into a container. Without a label, the security system might prevent the processes running inside the container from using the content. By default, Docker does not change the labels set by the OS. To change the label in the container context, you can add either of two suffixes `:z` or `:Z` to the volume mount. These suffixes tell Docker to relabel file objects on the shared volumes. The `z` option tells Docker that two containers share the volume content. As a result, Docker labels the content with a shared content label. Shared volume labels allow all containers to read/write content. The `Z` option tells Docker to label the content with a private unshared label. Only the current container can use a private volume. 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:ro --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)](/reference/run/#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: `=[:]`, 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` The values are sent to the appropriate `syscall` as they are set. Docker doesn't perform any byte conversion. Take this into account when setting the values. #### For `nproc` usage: Be careful setting `nproc` with the `ulimit` flag as `nproc` is designed by Linux to set the maximum number of processes available to a user, not to a container. For example, start four containers with `daemon` user: docker run -d -u daemon --ulimit nproc=3 busybox top docker run -d -u daemon --ulimit nproc=3 busybox top docker run -d -u daemon --ulimit nproc=3 busybox top docker run -d -u daemon --ulimit nproc=3 busybox top The 4th container fails and reports "[8] System error: resource temporarily unavailable" error. This fails because the caller set `nproc=3` resulting in the first three containers using up the three processes quota set for the `daemon` user.