@@ -24,4 +24,3 @@ to more substantial services like those which you might find in production.

    postgresql_service

    mongodb

    running_riak_service

-   linking_into_redis

deleted file mode 100644

@@ -1,137 +0,0 @@

-:title: Linking to an Redis container

-:description: Running redis linked into your web app

-:keywords: docker, example, networking, redis, link

-

-.. _linking_redis:

-

-Linking Redis

-=============

-

-.. include:: example_header.inc

-

-Building a Redis container to link as a child of our web application.

-

-Building the Redis container

-

-Lets build a Redis image with the following Dockerfile.

-

-First checkout the Redis source code.

-

-.. code-block:: bash

-

-    git clone https://github.com/antirez/redis.git

-    cd redis

-    git checkout 2.6

-

-

-Now let's create a Dockerfile in the root of the Redis repository.

-

-.. code-block:: bash

-

-    # Build redis from source

-    # Make sure you have the redis source code checked out in

-    # the same directory as this Dockerfile

-    FROM ubuntu

-

-    RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe" > /etc/apt/sources.list

-    RUN apt-get update

-    RUN apt-get upgrade -y

-

-    RUN apt-get install -y gcc make g++ build-essential libc6-dev tcl

-

-    ADD . /redis

-

-    RUN (cd /redis && make)

-

-    RUN mkdir -p /redis-data

-    VOLUME ["/redis-data"]

-    EXPOSE 6379

-

-    ENTRYPOINT ["/redis/src/redis-server"]

-    CMD ["--dir", "/redis-data"]

-

-    # docker build our new redis image from source

-    docker build -t redis-2.6 .

-

-

-We need to ``EXPOSE`` the default port of 6379 so that our link knows what ports 

-to connect to our Redis container on.  If you do not expose any ports for the

-image then docker will not be able to establish the link between containers.

-

-

-Run the Redis container

-

-.. code-block:: bash

-

-    sudo docker run -d -e PASSWORD=docker -name redis redis-2.6 --requirepass docker

-

-This will run our Redis container with the password docker 

-to secure our service.  By specifying the ``-name`` flag on run 

-we will assign the name ``redis`` to this container.  If we do not specify a name for 

-our container via the ``-name`` flag docker will automatically generate a name for us.

-We can issue all the commands that you would expect; start, stop, attach, using the name for our container.

-The name also allows us to link other containers into this one.

-

-Linking Redis as a child

-

-Next we can start a new web application that has a dependency on Redis and apply a link 

-to connect both containers.  If you noticed when running our Redis server we did not use

-the ``-p`` flag to publish the Redis port to the host system.  Redis exposed port 6379 via the Dockerfile 

-and this is all we need to establish a link.

-

-Now let's start our web application with a link into Redis.

-

-.. code-block:: bash

-

-    sudo docker run -t -i -link redis:db -name webapp ubuntu bash

-

-    root@4c01db0b339c:/# env

-

-    HOSTNAME=4c01db0b339c

-    DB_NAME=/webapp/db

-    TERM=xterm

-    DB_PORT=tcp://172.17.0.8:6379

-    DB_PORT_6379_TCP=tcp://172.17.0.8:6379

-    DB_PORT_6379_TCP_PROTO=tcp

-    DB_PORT_6379_TCP_ADDR=172.17.0.8

-    DB_PORT_6379_TCP_PORT=6379

-    PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

-    PWD=/

-    DB_ENV_PASSWORD=docker

-    SHLVL=1

-    HOME=/

-    container=lxc

-    _=/usr/bin/env

-    root@4c01db0b339c:/#

-

-

-When we inspect the environment of the linked container we can see a few extra environment 

-variables have been added.  When you specified ``-link redis:db`` you are telling docker

-to link the container named ``redis`` into this new container with the alias ``db``.

-Environment variables are prefixed with the alias so that the parent container can access

-network and environment information from the containers that are linked into it.

-

-.. code-block:: bash

-

-    # The name of the child container

-    DB_NAME=/webapp/db

-

-    # The default protocol, ip, and port of the service running in the container

-    DB_PORT=tcp://172.17.0.8:6379

-

-    # A specific protocol, ip, and port of various services

-    DB_PORT_6379_TCP=tcp://172.17.0.8:6379

-    DB_PORT_6379_TCP_PROTO=tcp

-    DB_PORT_6379_TCP_ADDR=172.17.0.8

-    DB_PORT_6379_TCP_PORT=6379

-

-    # Get environment variables of the container 

-    DB_ENV_PASSWORD=docker

-

-

-Accessing the network information along with the environment of the child container allows

-us to easily connect to the Redis service on the specific IP and port and use the password

-specified in the environment.