177 lines
5.6 KiB
Markdown
177 lines
5.6 KiB
Markdown
page_title: First steps with Docker
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page_description: Common usage and commands
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page_keywords: Examples, Usage, basic commands, docker, documentation, examples
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# First steps with Docker
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## Check your Docker install
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This guide assumes you have a working installation of Docker. To check
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your Docker install, run the following command:
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# Check that you have a working install
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docker info
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If you get `docker: command not found` or something
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like `/var/lib/docker/repositories: permission denied`
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you may have an incomplete docker installation or insufficient
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privileges to access Docker on your machine.
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Please refer to [*Installation*](../../installation/#installation-list)
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for installation instructions.
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## Download a pre-built image
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# Download an ubuntu image
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sudo docker pull ubuntu
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This will find the `ubuntu` image by name in the
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[*Central Index*](../workingwithrepository/#searching-central-index) and
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download it from the top-level Central Repository to a local image
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cache.
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> **Note**:
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> When the image has successfully downloaded, you will see a 12 character
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> hash `539c0211cd76: Download complete` which is the
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> short form of the image ID. These short image IDs are the first 12
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> characters of the full image ID - which can be found using
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> `docker inspect` or `docker images --no-trunc=true`
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**If you’re using OS X** then you shouldn’t use `sudo`.
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## Running an interactive shell
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# Run an interactive shell in the ubuntu image,
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# allocate a tty, attach stdin and stdout
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# To detach the tty without exiting the shell,
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# use the escape sequence Ctrl-p + Ctrl-q
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# note: This will continue to exist in a stopped state once exited (see "docker ps -a")
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sudo docker run -i -t ubuntu /bin/bash
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## Bind Docker to another host/port or a Unix socket
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> **Warning**:
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> Changing the default `docker` daemon binding to a
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> TCP port or Unix *docker* user group will increase your security risks
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> by allowing non-root users to gain *root* access on the host. Make sure
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> you control access to `docker`. If you are binding
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> to a TCP port, anyone with access to that port has full Docker access;
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> so it is not advisable on an open network.
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With `-H` it is possible to make the Docker daemon
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to listen on a specific IP and port. By default, it will listen on
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`unix:///var/run/docker.sock` to allow only local
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connections by the *root* user. You *could* set it to
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`0.0.0.0:4243` or a specific host IP to give access
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to everybody, but that is **not recommended** because then it is trivial
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for someone to gain root access to the host where the daemon is running.
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Similarly, the Docker client can use `-H` to connect
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to a custom port.
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`-H` accepts host and port assignment in the
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following format: `tcp://[host][:port]` or
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`unix://path`
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For example:
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- `tcp://host:4243` -\> tcp connection on
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host:4243
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- `unix://path/to/socket` -\> unix socket located
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at `path/to/socket`
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`-H`, when empty, will default to the same value as
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when no `-H` was passed in.
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`-H` also accepts short form for TCP bindings:
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`host[:port]` or `:port`
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# Run docker in daemon mode
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sudo <path to>/docker -H 0.0.0.0:5555 -d &
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# Download an ubuntu image
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sudo docker -H :5555 pull ubuntu
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You can use multiple `-H`, for example, if you want
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to listen on both TCP and a Unix socket
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# Run docker in daemon mode
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sudo <path to>/docker -H tcp://127.0.0.1:4243 -H unix:///var/run/docker.sock -d &
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# Download an ubuntu image, use default Unix socket
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sudo docker pull ubuntu
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# OR use the TCP port
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sudo docker -H tcp://127.0.0.1:4243 pull ubuntu
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## Starting a long-running worker process
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# Start a very useful long-running process
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JOB=$(sudo docker run -d ubuntu /bin/sh -c "while true; do echo Hello world; sleep 1; done")
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# Collect the output of the job so far
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sudo docker logs $JOB
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# Kill the job
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sudo docker kill $JOB
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## Listing containers
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sudo docker ps # Lists only running containers
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sudo docker ps -a # Lists all containers
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## Controlling containers
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# Start a new container
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JOB=$(sudo docker run -d ubuntu /bin/sh -c "while true; do echo Hello world; sleep 1; done")
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# Stop the container
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docker stop $JOB
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# Start the container
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docker start $JOB
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# Restart the container
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docker restart $JOB
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# SIGKILL a container
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docker kill $JOB
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# Remove a container
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docker stop $JOB # Container must be stopped to remove it
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docker rm $JOB
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## Bind a service on a TCP port
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# Bind port 4444 of this container, and tell netcat to listen on it
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JOB=$(sudo docker run -d -p 4444 ubuntu:12.10 /bin/nc -l 4444)
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# Which public port is NATed to my container?
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PORT=$(sudo docker port $JOB 4444 | awk -F: '{ print $2 }')
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# Connect to the public port
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echo hello world | nc 127.0.0.1 $PORT
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# Verify that the network connection worked
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echo "Daemon received: $(sudo docker logs $JOB)"
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## Committing (saving) a container state
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Save your containers state to a container image, so the state can be
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re-used.
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When you commit your container only the differences between the image
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the container was created from and the current state of the container
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will be stored (as a diff). See which images you already have using the
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`docker images` command.
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# Commit your container to a new named image
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sudo docker commit <container_id> <some_name>
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# List your containers
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sudo docker images
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You now have a image state from which you can create new instances.
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Read more about [*Share Images via
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Repositories*](../workingwithrepository/#working-with-the-repository) or
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continue to the complete [*Command
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Line*](../../reference/commandline/cli/#cli)
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