# Dockerizing a Redis service 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. FROM ubuntu:14.04 RUN apt-get update && apt-get install -y redis-server EXPOSE 6379 ENTRYPOINT ["/usr/bin/redis-server"] Next we build an image from our `Dockerfile`. Replace `` with your own user name. $ docker build -t /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. $ docker run --name redis -d /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. $ docker run --link redis:db -i -t ubuntu:14.04 /bin/bash Once inside our freshly created container we need to install Redis to get the `redis-cli` binary to test our connection. $ sudo apt-get update $ sudo apt-get install redis-server $ sudo service redis-server stop As we've used the `--link redis:db` option, Docker has created some environment variables in our web application container. $ env | grep DB_ # Should return something similar to this with your values 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. $ 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.