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180 lines
4.6 KiB
ReStructuredText
180 lines
4.6 KiB
ReStructuredText
:title: Hello world example
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:description: A simple hello world example with Docker
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:keywords: docker, example, hello world
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.. _examples:
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Hello World
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-----------
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.. _running_examples:
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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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.. _hello_world:
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Hello World
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===========
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.. include:: example_header.inc
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This is the most basic example available for using Docker.
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Download the base image which is named ``ubuntu``:
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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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Alternatively to the ``ubuntu`` image, you can select ``busybox``, a bare
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minimal Linux system. The images are retrieved from the Docker
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repository.
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.. code-block:: bash
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sudo docker run ubuntu /bin/echo hello world
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This command will run a simple ``echo`` command, that will echo ``hello world`` back to the console over standard out.
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**Explanation:**
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- **"sudo"** execute the following commands as user *root*
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- **"docker run"** run a command in a new container
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- **"ubuntu"** is the image we want to run the command inside of.
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- **"/bin/echo"** is the command we want to run in the container
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- **"hello world"** is the input for the echo command
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**Video:**
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See the example in action
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.. raw:: html
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<div style="margin-top:10px;">
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<iframe width="560" height="350" src="http://ascii.io/a/2603/raw" frameborder="0"></iframe>
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</div>
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----
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.. _hello_world_daemon:
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Hello World Daemon
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==================
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.. include:: example_header.inc
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And now for the most boring daemon ever written!
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We will use the Ubuntu image to run a simple hello world daemon that will just print hello
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world to standard out every second. It will continue to do this until
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we stop it.
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**Steps:**
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.. code-block:: bash
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CONTAINER_ID=$(sudo docker run -d ubuntu /bin/sh -c "while true; do echo hello world; sleep 1; done")
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We are going to run a simple hello world daemon in a new container
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made from the ``ubuntu`` image.
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- **"sudo docker run -d "** run a command in a new container. We pass "-d"
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so it runs as a daemon.
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- **"ubuntu"** is the image we want to run the command inside of.
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- **"/bin/sh -c"** is the command we want to run in the container
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- **"while true; do echo hello world; sleep 1; done"** is the mini
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script we want to run, that will just print hello world once a
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second until we stop it.
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- **$CONTAINER_ID** the output of the run command will return a
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container id, we can use in future commands to see what is going on
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with this process.
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.. code-block:: bash
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sudo docker logs $CONTAINER_ID
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Check the logs make sure it is working correctly.
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- **"docker logs**" This will return the logs for a container
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- **$CONTAINER_ID** The Id of the container we want the logs for.
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.. code-block:: bash
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sudo docker attach -sig-proxy=false $CONTAINER_ID
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Attach to the container to see the results in real-time.
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- **"docker attach**" This will allow us to attach to a background
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process to see what is going on.
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- **"-sig-proxy=false"** Do not forward signals to the container; allows
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us to exit the attachment using Control-C without stopping the container.
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- **$CONTAINER_ID** The Id of the container we want to attach too.
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Exit from the container attachment by pressing Control-C.
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.. code-block:: bash
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sudo docker ps
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Check the process list to make sure it is running.
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- **"docker ps"** this shows all running process managed by docker
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.. code-block:: bash
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sudo docker stop $CONTAINER_ID
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Stop the container, since we don't need it anymore.
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- **"docker stop"** This stops a container
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- **$CONTAINER_ID** The Id of the container we want to stop.
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.. code-block:: bash
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sudo docker ps
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Make sure it is really stopped.
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**Video:**
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See the example in action
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.. raw:: html
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<div style="margin-top:10px;">
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<iframe width="560" height="350" src="http://ascii.io/a/2562/raw" frameborder="0"></iframe>
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</div>
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The next example in the series is a :ref:`python_web_app` example, or
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you could skip to any of the other examples:
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* :ref:`python_web_app`
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* :ref:`nodejs_web_app`
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* :ref:`running_redis_service`
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* :ref:`running_ssh_service`
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* :ref:`running_couchdb_service`
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* :ref:`postgresql_service`
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* :ref:`mongodb_image`
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