added support for linking to a redis container

Changelog.md

@@ -1,6 +1,7 @@
 # Changelog
 
 **latest**
+- added support for linking with redis container.
 - use sameersbn/ubuntu as the base docker image
 - install postgresql-client to fix restoring backups when used with a postgresql database backend.
 

README.md

@@ -19,6 +19,10 @@
         - [PostgreSQL](#postgresql)
             - [External PostgreSQL Server](#external-postgresql-server)
             - [Linking to PostgreSQL Container](#linking-to-postgresql-container)
+    - [Redis](#redis)
+      - [Internal Redis Server](#internal-redis-server)
+      - [External Redis Server](#external-redis-server)
+      - [Linking to Redis Container](#linking-to-redis-container)
     - [Mail](#mail)
     - [Putting it all together](#putting-it-all-together)
     - [Available Configuration Parameters](#available-configuration-parameters)
@@ -348,6 +352,53 @@ docker run --name=gitlab -d --link postgresql:postgresql \
   sameersbn/gitlab:latest
 ```
 
+## Redis
+
+### Internal Redis Server
+
+> **Warning**
+>
+> The internal redis server will soon be removed from the image.
+
+> Please use a linked [redis](#linking-to-redis-container) container
+> or a external [redis](#external-redis-server) server
+
+> You've been warned.
+
+GitLab uses the redis server for its key-value data store. The redis server connection details can be specified using environment variables. If not specified, the  starts a redis server internally, no additional configuration is required.
+
+### External Redis Server
+The image can be configured to use an external redis server instead of starting a redis server internally. The configuration should be specified using environment variables while starting the GitLab image.
+
+*Assuming that the redis server host is 192.168.1.100*
+
+```bash
+docker run --name=gitlab -i -t --rm \
+  -e "REDIS_HOST=192.168.1.100" -e "REDIS_PORT=6379" \
+  sameersbn/gitlab:latest
+```
+### Linking to Redis Container
+You can link this image with a redis container to satisfy gitlab's redis requirement. The alias of the redis server container should be set to **redisio** while linking with the gitlab image.
+
+To illustrate linking with a redis container, we will use the [sameersbn/redis](https://github.com/sameersbn/docker-redis) image. Please refer the [README](https://github.com/sameersbn/docker-redis/blob/master/README.md) of docker-redis for details.
+
+First, lets pull the redis image from the docker index.
+```bash
+docker pull sameersbn/redis:latest
+```
+
+Lets start the redis container
+```bash
+docker run --name=redis -d sameersbn/redis:latest
+```
+
+We are now ready to start the GitLab application.
+
+```bash
+docker run --name=gitlab -d --link redis:redisio \
+  sameersbn/gitlab:latest
+```
+
 ### Mail
 The mail configuration should be specified using environment variables while starting the GitLab image. The configuration defaults to using gmail to send emails and requires the specification of a valid username and password to login to the gmail servers.
 

assets/init

@@ -14,8 +14,8 @@ GITLAB_BACKUP_EXPIRY=${GITLAB_BACKUP_EXPIRY:-}
 
 GITLAB_SHELL_SSH_PORT=${GITLAB_SHELL_SSH_PORT:-22}
 
-REDIS_HOST=${REDIS_HOST:-localhost}
-REDIS_PORT=${REDIS_PORT:-6379}
+REDIS_HOST=${REDIS_HOST:-}
+REDIS_PORT=${REDIS_PORT:-}
 
 UNICORN_WORKERS=${UNICORN_WORKERS:-2}
 UNICORN_TIMEOUT=${UNICORN_TIMEOUT:-60}
@@ -49,6 +49,16 @@ LDAP_ALLOW_USERNAME_OR_EMAIL_LOGIN=${LDAP_ALLOW_USERNAME_OR_EMAIL_LOGIN:-}
 LDAP_BASE=${LDAP_BASE:-}
 LDAP_USER_FILTER=${LDAP_USER_FILTER:-}
 
+# is a redis container linked?
+if [ -n "${REDISIO_PORT_6379_TCP_ADDR}" ]; then
+	REDIS_HOST=${REDIS_HOST:-${REDISIO_PORT_6379_TCP_ADDR}}
+	REDIS_PORT=${REDIS_PORT:-${REDISIO_PORT_6379_TCP_PORT}}
+fi
+
+# fallback to using internal redis server
+REDIS_HOST=${REDIS_HOST:-localhost}
+REDIS_PORT=${REDIS_PORT:-6379}
+
 # is a mysql or postgresql database linked?
 # requires that the mysql or postgresql containers have exposed
 # port 3306 and 5432 respectively.