From c9cedb4c0484c3e1879495ab5c02088ae738763e Mon Sep 17 00:00:00 2001 From: James Turnbull Date: Mon, 9 Dec 2013 16:47:19 -0800 Subject: [PATCH] Some minor cleanup of the Links use document --- docs/sources/use/working_with_links_names.rst | 26 ++++++++++--------- 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/docs/sources/use/working_with_links_names.rst b/docs/sources/use/working_with_links_names.rst index e6ab9395f8..6283a865f8 100644 --- a/docs/sources/use/working_with_links_names.rst +++ b/docs/sources/use/working_with_links_names.rst @@ -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 +