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170 lines
5.2 KiB
ReStructuredText
:title: First steps with Docker
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:description: Common usage and commands
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:keywords: Examples, Usage, basic commands, docker, documentation, examples
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First steps with Docker
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=======================
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Check your Docker install
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-------------------------
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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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.. code-block:: bash
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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 like
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``/var/lib/docker/repositories: permission denied`` you may have an incomplete
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docker installation or insufficient privileges to access Docker on your machine.
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Please refer to :ref:`installation_list` for installation instructions.
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Download a pre-built image
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--------------------------
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.. code-block:: bash
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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 :ref:`Central Index
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<searching_central_index>` and download it from the top-level Central
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Repository to a local image cache.
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.. NOTE:: When the image has successfully downloaded, you will see a
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12 character 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 ``docker
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inspect`` or ``docker images -notrunc=true``
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Running an interactive shell
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----------------------------
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.. code-block:: bash
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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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sudo docker run -i -t ubuntu /bin/bash
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.. _bind_docker:
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Bind Docker to another host/port or a Unix socket
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-------------------------------------------------
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.. warning:: Changing the default ``docker`` daemon binding to a TCP
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port or Unix *docker* user group will increase your security risks
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by allowing non-root users to potentially gain *root* access on the
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host (`e.g. #1369
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<https://github.com/dotcloud/docker/issues/1369>`_). Make sure you
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control access to ``docker``.
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With ``-H`` it is possible to make the Docker daemon to listen on a
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specific IP and port. By default, it will listen on
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``unix:///var/run/docker.sock`` to allow only local connections by the
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*root* user. You *could* set it to ``0.0.0.0:4243`` or a specific host IP to
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give access to everybody, but that is **not recommended** because then
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it is trivial for someone to gain root access to the host where the
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daemon is running.
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Similarly, the Docker client can use ``-H`` to connect to a custom port.
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``-H`` accepts host and port assignment in the following format:
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``tcp://[host][:port]`` or ``unix://path``
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For example:
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* ``tcp://host:4243`` -> tcp connection on host:4243
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* ``unix://path/to/socket`` -> unix socket located at ``path/to/socket``
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``-H``, when empty, will default to the same value as 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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.. code-block:: bash
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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 to listen on
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both TCP and a Unix socket
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.. code-block:: bash
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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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--------------------------------------
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.. code-block:: bash
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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 $JOB
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Listing all running containers
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------------------------------
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.. code-block:: bash
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sudo docker ps
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Bind a service on a TCP port
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------------------------------
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.. code-block:: bash
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# Bind port 4444 of this container, and tell netcat to listen on it
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JOB=$(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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-------------------------------------
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Save your containers state to a container image, so the state can be re-used.
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When you commit your container only the differences between the image the
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container was created from and the current state of the container will be
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stored (as a diff). See which images you already have using the ``docker
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images`` command.
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.. code-block:: bash
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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 :ref:`working_with_the_repository` or continue to the
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complete :ref:`cli`
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