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101 lines
3 KiB
ReStructuredText
101 lines
3 KiB
ReStructuredText
:title: Running a Redis service
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:description: Installing and running an redis service
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:keywords: docker, example, package installation, networking, redis
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.. _running_redis_service:
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Redis Service
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=============
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.. include:: example_header.inc
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Very simple, no frills, Redis service attached to a web application using a link.
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Create a docker container for Redis
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-----------------------------------
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Firstly, we create a ``Dockerfile`` for our new Redis image.
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.. code-block:: bash
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FROM ubuntu:12.10
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RUN apt-get update
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RUN apt-get -y install redis-server
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EXPOSE 6379
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ENTRYPOINT ["/usr/bin/redis-server"]
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Next we build an image from our ``Dockerfile``. Replace ``<your username>``
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with your own user name.
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.. code-block:: bash
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sudo docker build -t <your username>/redis .
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Run the service
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---------------
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Use the image we've just created and name your container ``redis``.
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Running the service with ``-d`` runs the container in detached mode, leaving the
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container running in the background.
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Importantly, we're not exposing any ports on our container. Instead we're going to
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use a container link to provide access to our Redis database.
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.. code-block:: bash
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sudo docker run -name redis -d <your username>/redis
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Create your web application container
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-------------------------------------
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Next we can create a container for our application. We're going to use the ``-link``
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flag to create a link to the ``redis`` container we've just created with an alias of
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``db``. This will create a secure tunnel to the ``redis`` container and expose the
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Redis instance running inside that container to only this container.
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.. code-block:: bash
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sudo docker run -link redis:db -i -t ubuntu:12.10 /bin/bash
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Once inside our freshly created container we need to install Redis to get the
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``redis-cli`` binary to test our connection.
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.. code-block:: bash
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apt-get update
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apt-get -y install redis-server
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service redis-server stop
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Now we can test the connection. Firstly, let's look at the available environmental
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variables in our web application container. We can use these to get the IP and port
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of our ``redis`` container.
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.. code-block:: bash
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env
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. . .
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DB_NAME=/violet_wolf/db
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DB_PORT_6379_TCP_PORT=6379
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DB_PORT=tcp://172.17.0.33:6379
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DB_PORT_6379_TCP=tcp://172.17.0.33:6379
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DB_PORT_6379_TCP_ADDR=172.17.0.33
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DB_PORT_6379_TCP_PROTO=tcp
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We can see that we've got a small list of environment variables prefixed with ``DB``.
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The ``DB`` comes from the link alias specified when we launched the container. Let's use
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the ``DB_PORT_6379_TCP_ADDR`` variable to connect to our Redis container.
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.. code-block:: bash
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redis-cli -h $DB_PORT_6379_TCP_ADDR
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redis 172.17.0.33:6379>
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redis 172.17.0.33:6379> set docker awesome
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OK
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redis 172.17.0.33:6379> get docker
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"awesome"
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redis 172.17.0.33:6379> exit
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We could easily use this or other environment variables in our web application to make a
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connection to our ``redis`` container.
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