зеркало из https://github.com/microsoft/docker.git
Merge pull request #2557 from jamtur01/new_redis
Updated Redis service example to use links. Removed "Linking Redis" example as redundant.
This commit is contained in:
Andy Rothfusz
Коммит
37dcff0c13
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@ -24,4 +24,3 @@ to more substantial services like those which you might find in production.
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postgresql_service
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mongodb
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running_riak_service
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linking_into_redis
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@ -1,137 +0,0 @@
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:title: Linking to an Redis container
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:description: Running redis linked into your web app
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:keywords: docker, example, networking, redis, link
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.. _linking_redis:
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Linking Redis
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=============
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.. include:: example_header.inc
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Building a Redis container to link as a child of our web application.
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Building the Redis container
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----------------------------
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Lets build a Redis image with the following Dockerfile.
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First checkout the Redis source code.
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.. code-block:: bash
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git clone https://github.com/antirez/redis.git
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cd redis
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git checkout 2.6
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Now let's create a Dockerfile in the root of the Redis repository.
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.. code-block:: bash
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# Build redis from source
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# Make sure you have the redis source code checked out in
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# the same directory as this Dockerfile
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FROM ubuntu
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RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe" > /etc/apt/sources.list
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RUN apt-get update
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RUN apt-get upgrade -y
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RUN apt-get install -y gcc make g++ build-essential libc6-dev tcl
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ADD . /redis
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RUN (cd /redis && make)
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RUN mkdir -p /redis-data
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VOLUME ["/redis-data"]
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EXPOSE 6379
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ENTRYPOINT ["/redis/src/redis-server"]
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CMD ["--dir", "/redis-data"]
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# docker build our new redis image from source
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docker build -t redis-2.6 .
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We need to ``EXPOSE`` the default port of 6379 so that our link knows what ports
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to connect to our Redis container on. If you do not expose any ports for the
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image then docker will not be able to establish the link between containers.
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Run the Redis container
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-----------------------
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.. code-block:: bash
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sudo docker run -d -e PASSWORD=docker -name redis redis-2.6 --requirepass docker
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This will run our Redis container with the password docker
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to secure our service. By specifying the ``-name`` flag on run
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we will assign the name ``redis`` to this container. If we do not specify a name for
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our container via the ``-name`` flag docker will automatically generate a name for us.
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We can issue all the commands that you would expect; start, stop, attach, using the name for our container.
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The name also allows us to link other containers into this one.
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Linking Redis as a child
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------------------------
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Next we can start a new web application that has a dependency on Redis and apply a link
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to connect both containers. If you noticed when running our Redis server we did not use
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the ``-p`` flag to publish the Redis port to the host system. Redis exposed port 6379 via the Dockerfile
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and this is all we need to establish a link.
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Now let's start our web application with a link into Redis.
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.. code-block:: bash
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sudo docker run -t -i -link redis:db -name webapp ubuntu bash
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root@4c01db0b339c:/# env
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HOSTNAME=4c01db0b339c
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DB_NAME=/webapp/db
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TERM=xterm
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DB_PORT=tcp://172.17.0.8:6379
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DB_PORT_6379_TCP=tcp://172.17.0.8:6379
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DB_PORT_6379_TCP_PROTO=tcp
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DB_PORT_6379_TCP_ADDR=172.17.0.8
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DB_PORT_6379_TCP_PORT=6379
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PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
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PWD=/
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DB_ENV_PASSWORD=docker
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SHLVL=1
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HOME=/
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container=lxc
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_=/usr/bin/env
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root@4c01db0b339c:/#
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When we inspect the environment of the linked container we can see a few extra environment
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variables have been added. When you specified ``-link redis:db`` you are telling docker
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to link the container named ``redis`` into this new container with the alias ``db``.
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Environment variables are prefixed with the alias so that the parent container can access
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network and environment information from the containers that are linked into it.
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.. code-block:: bash
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# The name of the child container
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DB_NAME=/webapp/db
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# The default protocol, ip, and port of the service running in the container
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DB_PORT=tcp://172.17.0.8:6379
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# A specific protocol, ip, and port of various services
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DB_PORT_6379_TCP=tcp://172.17.0.8:6379
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DB_PORT_6379_TCP_PROTO=tcp
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DB_PORT_6379_TCP_ADDR=172.17.0.8
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DB_PORT_6379_TCP_PORT=6379
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# Get environment variables of the container
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DB_ENV_PASSWORD=docker
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Accessing the network information along with the environment of the child container allows
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us to easily connect to the Redis service on the specific IP and port and use the password
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specified in the environment.
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@ -9,74 +9,93 @@ Redis Service
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.. include:: example_header.inc
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Very simple, no frills, Redis service.
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Very simple, no frills, Redis service attached to a web application using a link.
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Open a docker container
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-----------------------
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Create a docker container for Redis
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-----------------------------------
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Firstly, we create a ``Dockerfile`` for our new Redis image.
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.. code-block:: bash
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sudo docker run -i -t ubuntu /bin/bash
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FROM ubuntu:12.10
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RUN apt-get update
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RUN apt-get -y install redis-server
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EXPOSE 6379
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ENTRYPOINT ["/usr/bin/redis-server"]
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Building your image
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-------------------
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Update your Docker container, install the Redis server. Once
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installed, exit out of the Docker container.
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Next we build an image from our ``Dockerfile``. Replace ``<your username>``
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with your own user name.
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.. code-block:: bash
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apt-get update
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apt-get install redis-server
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exit
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Snapshot the installation
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-------------------------
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.. code-block:: bash
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sudo docker ps -a # grab the container id (this will be the first one in the list)
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sudo docker commit <container_id> <your username>/redis
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sudo docker build -t <your username>/redis
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Run the service
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---------------
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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 the
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container running in the background. Use your snapshot.
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container running in the background.
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Importantly, we're not exposing any ports on our container. Instead we're going to
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use a container link to provide access to our Redis database.
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.. code-block:: bash
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sudo docker run -d -p 6379 <your username>/redis /usr/bin/redis-server
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sudo docker run -name redis -d <your username>/redis
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Test 1
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++++++
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Create your web application container
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-------------------------------------
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Connect to the container with the ``redis-cli`` binary.
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Next we can create a container for our application. We're going to use the ``-link``
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flag to create a link to the ``redis`` container we've just created with an alias of
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``db``. This will create a secure tunnel to the ``redis`` container and expose the
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Redis instance running inside that container to only this container.
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.. code-block:: bash
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sudo docker ps # grab the new container id
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sudo docker inspect <container_id> # grab the ipaddress of the container
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redis-cli -h <ipaddress> -p 6379
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redis 10.0.3.32:6379> set docker awesome
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sudo docker run -link redis:db -i -t ubuntu:12.10 /bin/bash
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Once inside our freshly created container we need to install Redis to get the
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``redis-cli`` binary to test our connection.
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.. code-block:: bash
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apt-get update
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apt-get -y install redis-server
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service redis-server stop
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Now we can test the connection. Firstly, let's look at the available environmental
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variables in our web application container. We can use these to get the IP and port
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of our ``redis`` container.
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.. code-block:: bash
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env
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. . .
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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 environmental varaibles prefixed with ``DB``.
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The ``DB`` comes from the link alias specified when we launched the container. Let's use
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the ``DB_PORT_6379_TCP_ADDR`` variable to connect to our Redis container.
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.. code-block:: bash
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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 10.0.3.32:6379> get docker
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redis 172.17.0.33:6379> get docker
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"awesome"
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redis 10.0.3.32:6379> exit
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redis 172.17.0.33:6379> exit
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Test 2
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++++++
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We could easily use this or other environment variables in our web application to make a
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connection to our ``redis`` container.
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Connect to the host os with the ``redis-cli`` binary.
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.. code-block:: bash
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sudo docker ps # grab the new container id
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sudo docker port <container_id> 6379 # grab the external port
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ip addr show # grab the host ip address
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redis-cli -h <host ipaddress> -p <external port>
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redis 192.168.0.1:49153> set docker awesome
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OK
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redis 192.168.0.1:49153> get docker
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"awesome"
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redis 192.168.0.1:49153> exit
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