Docker run
External
- https://docs.docker.com/engine/reference/commandline/run/
- https://docs.docker.com/engine/reference/run/
Internal
Overview
Without any arguments except the name of image, it creates a new container based on the given image, and executes it in the foreground, connecting the current terminal's stdin/stdout/stderr to the container:
docker run novaordis/centos-loop
The docker runtime will first attempt to use an image from the local registry, and if it does find it, it will attempt to pull it from Docker Hub and then cache locally in the local registry.
In order to run the container in the background, use -d | --detach.
The generic format of the command is:
docker run [options] <image> [command] [args...]
Example:
docker run -d --name="runloop1" -e SOME_ENV_VAR="some value" \
busybox \
/bin/sh -c 'i=0; while true; do echo ${i}; i=$(expr ${i} + 1); sleep 1s; done'
A running container, either in foreground or background, can be with listed with:
docker ps
it can be stopped with:
docker stop
and then it can be restarted with:
docker start
Anything that a running container sends to stdout can be explored with docker logs.
More container operations:
The Run Process
Options
-i, --interactive
Start the container in interactive mode.
-d, --detach
Start the container in detached mode and print the container ID.
Note that -a|--attach and -d|--detach are mutually exclusive.
-a, --attach
-a|--attach <stream-name>
where the stream name may be "STDIN", "stdin", "STDOUT", "stdout", "STDERR" or "stderr". Specifies what standard streams to attach to. By default, all are attached.
If multiple streams are to be attached, the syntax is:
-a STDIN -a STDOUT -a STDERR
Note that -a|--attach and -d|--detach are mutually exclusive.
For more details, see:
-t, --tty
Associate the container with a TTY device.
--entrypoint
If ENTRYPOINT is specified in the container metadata, it can be overridden on command line with:
docker run --entrypoint <other-entrypoint>
Example:
docker run --entrypoint bash -it novaordis/someimage:latest
For more details see:
-e, --env
-e SOME_ENV_VAR="some value"
Set environment variables. Default values for those environment variables can be declared in the Dockerfile with ENV. Those values will be overridden by the command line value.
--name
Assign a name to the container, otherwise the name will be assigned automatically to something like "pedantic_einstein" or "competent_aryabhata".
--name="bluebox"
--restart
Configures the restart policy of the container being created. The restart policy applies when container exits.
--restart=always
See:
-p, --publish
-p|--publish list
Publish a container's port(s) to the host. Also see Dockerfile EXPOSE.
To publish port 8080:
docker run ... -p 8080:8080/tcp ...
Port Mapping
-p <host-port>:<container-port>
Maps the specified container port to the specified host port.
-P, --publish-all
Publish all exposed ports to random ports. Also see Dockerfile EXPOSE.
-v, --volume
See:
--mount
See:
--rm
Automatically remove the container when it exits.
--network
The option is used to connect a container to a user-defined network. If not specified, the container is connected to the default network, which is the default "bridge" network. "Connecting" in this context means that the command associates the container with the specified network and "plugs it" into the network. After the command completes, the container's IP is routable outside to the Docker host.
docker run ... --network <network-name> ...
--storage-opt list
Storage driver options for the container. Controls the following:
Base Device Size
The amount of storage allocated to the container when the image is run (this was only tested with device-mapper):
... --storage-opt size=20G ...
This value cannot be smaller than the default value, see device-mapper Base Device Size.
-h
Resource Management Options
-m, --memory
The memory limit, in bytes. Apparently, that means the same amount will be allowed for "RAM" and swap, so a process can use double the specified amount, if it starts swapping. Also see Resource Management.
--link
Add link to another container.
Troubleshooting
User has No Appropriate Permissions
The attempt to run the ps or run command under a user that has no appropriate permissions leads to:
Cannot connect to the Docker daemon. Is the docker daemon running on this host?