90 lines
2.8 KiB
Markdown
90 lines
2.8 KiB
Markdown
<!--[metadata]>
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+++
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title = "Dockerizing a Redis service"
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description = "Installing and running a redis service"
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keywords = ["docker, example, package installation, networking, redis"]
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[menu.main]
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parent = "engine_dockerize"
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+++
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<![end-metadata]-->
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# Dockerizing a Redis service
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Very simple, no frills, Redis service attached to a web application
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using a link.
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## Create a Docker container for Redis
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Firstly, we create a `Dockerfile` for our new Redis
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image.
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FROM ubuntu:14.04
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RUN apt-get update && apt-get install -y 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`.
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Replace `<your username>` with your own user name.
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$ docker build -t <your username>/redis .
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## Run the service
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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
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the container running in the background.
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Importantly, we're not exposing any ports on our container. Instead
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we're going to use a container link to provide access to our Redis
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database.
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$ docker run --name redis -d <your username>/redis
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## Create your web application container
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Next we can create a container for our application. We're going to use
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the `-link` flag to create a link to the `redis` container we've just
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created with an alias of `db`. This will create a secure tunnel to the
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`redis` container and expose the Redis instance running inside that
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container to only this container.
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$ docker run --link redis:db -i -t ubuntu:14.04 /bin/bash
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Once inside our freshly created container we need to install Redis to
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get the `redis-cli` binary to test our connection.
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$ sudo apt-get update
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$ sudo apt-get install redis-server
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$ sudo service redis-server stop
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As we've used the `--link redis:db` option, Docker
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has created some environment variables in our web application container.
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$ env | grep DB_
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# Should return something similar to this with your values
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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
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with `DB`. The `DB` comes from the link alias specified when we launched
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the container. Let's use the `DB_PORT_6379_TCP_ADDR` variable to connect to
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our Redis container.
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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
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application to make a connection to our `redis`
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container.
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