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Some minor cleanup of the Links use document

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James Turnbull 2013-12-09 16:47:19 -08:00
parent b7bc80cba9
commit c9cedb4c04
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docs/sources/use/working_with_links_names.rst
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@ -1,6 +1,6 @@
: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
:keywords: Examples, Usage, links, linking, docker, documentation, examples, names, name, container naming
.. _working_with_links_names:
@ -40,7 +40,7 @@ Links: service discovery for docker
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
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
@ -52,28 +52,29 @@ a secure tunnel for the parent to access. If a database container only exposes p
then the linked container will only be allowed to access port 8080 and nothing else if
inter-container communication is set to false.
For example, there is an image called ``crosbymichael/redis`` that exposes the
port 6379 and starts the Redis server. Let's name the container as ``redis``
based on that image and run it as daemon.
.. code-block:: bash
# Example: there is an image called crosbymichael/redis 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 crosbymichael/redis
We can issue all the commands that you would expect using the name "redis"; start, stop,
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
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
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.
@ -103,11 +104,12 @@ about the child container.
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.
Running ``docker ps`` shows the 2 containers, and the webapp/db alias name for the redis container.
Running ``docker ps`` shows the 2 containers, and the ``webapp/db`` alias name for the redis container.
.. code-block:: bash
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4c01db0b339c ubuntu:12.04 bash 17 seconds ago Up 16 seconds webapp
d7886598dbe2 crosbymichael/redis:latest /redis-server --dir 33 minutes ago Up 33 minutes 6379/tcp redis,webapp/db
4c01db0b339c ubuntu:12.04 bash 17 seconds ago Up 16 seconds webapp
d7886598dbe2 crosbymichael/redis:latest /redis-server --dir 33 minutes ago Up 33 minutes 6379/tcp redis,webapp/db