diff --git a/docs/sources/use/index.rst b/docs/sources/use/index.rst index 914d5a2a21..38f61ba744 100644 --- a/docs/sources/use/index.rst +++ b/docs/sources/use/index.rst @@ -20,3 +20,4 @@ Contents: puppet host_integration working_with_volumes + working_with_links_names diff --git a/docs/sources/use/working_with_links_names.rst b/docs/sources/use/working_with_links_names.rst new file mode 100644 index 0000000000..ad88b5f910 --- /dev/null +++ b/docs/sources/use/working_with_links_names.rst @@ -0,0 +1,98 @@ +:title: Working with Links and Names +:description: How to create and use links and names +:keywords: Examples, Usage, links, docker, documentation, examples, names, name, container naming + +.. _working_with_links_names: + +Working with Links and Names +============================ + +From version 0.6.5 you are able to ``name`` a container and ``link`` it to another +container by referring its name. This will create a relation parent->child where +the parent container can see all the important information about its child. + +.. _run_name: + +Container Naming +---------------- + +.. versionadded:: v0.6.5 + +You can now name your container by using ``-name`` flag. If no name is provided, +Docker will automatically generate a name which can be seen by typing: ``docker ps``. + +.. code-block:: bash + + # format is "sudo docker run -name " + $ sudo docker run -name test ubuntu /bin/bash + +.. _run_link: + +Links: service discovery for docker +----------------------------------- + +.. versionadded:: v0.6.5 + +Links allow containers to discover and securely communicate with each other by using the +flag ``-link name:alias``. Inter-container communication can be disabled with the daemon +flag ``-icc=false``. With this flag set to false, Container A cannot access Container B +unless explicitly allowed via a link. This is a huge win for securing your containers. +When two containers are linked together Docker creates a parent child relationship +between the containers. The parent container will be able to access information via +env variables of the child such as name, exposed ports, ip, and environment variables. + +When linking two containers Docker will use the exposed ports of the container to create +a secure tunnel for the parent to access. If a database container only exposes port 8080 +then the linked container will only be allowed to access port 8080 and nothing else if +inter-container communication is set to false. + +.. code-block:: bash + + # Example: there is an image called redis-2.6 that exposes the port 6379 and starts redis-server. + # Let's name the container as "redis" based on that image and run it as daemon. + $ sudo docker run -d -name redis redis-2.6 + +We can issue all the commands that you would expect using the name "redis"; start, stop, +attach, using the name for our container. The name also allows us to link other containers +into this one. + +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 and +this is all we need to establish a link. + +.. code-block:: bash + + # Linking the redis container as a child + $ sudo docker run -t -i -link redis:db -name webapp ubuntu bash + +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. + +If we inspect the environment variables of the second container, we would see all the information +about the child container. + +.. code-block:: bash + + $ sroot@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=/ + SHLVL=1 + HOME=/ + container=lxc + _=/usr/bin/env + root@4c01db0b339c:/# + +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 in the environment.