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moby--moby/docs/sources/examples/running_redis_service.rst
2013-11-19 14:44:50 +01:00

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