2.8 KiB
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 <your username> with your own user name.
$ 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.
$ 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.
$ 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.