Merge branch 'add-redis-config-options' into 'master'

Add configurable option of 'maxclients' to redis tunables

Adds templating, documentation, and defaults for tuning the Redis 'maxclients' attribute that governs the maximum number of connections a Redis server may serve.

Resolves #1339 

See merge request !812

doc/settings/redis.md

@@ -26,3 +26,15 @@ managed by omnibus-gitlab reachable via TCP.
 redis['port'] = 6379
 redis['bind'] = '127.0.0.1'
 ```
+
+## Increasing the number of Redis connections beyond the default
+
+By default Redis will only accept 10,000 client connections. If you need
+more that 10,000 connections set the 'maxclients' attribute to suite your needs.
+Be advised that adjusting the maxclients attribute means that you will also need
+to take into account your systems settings for fs.file-max (i.e. "sysctl -w fs.file-max=20000")
+
+```ruby
+redis['maxclients'] = 20000
+```
+

files/gitlab-config-template/gitlab.rb.template

@@ -489,6 +489,7 @@ external_url 'GENERATED_EXTERNAL_URL'
 
 # redis['enable'] = true
 # redis['username'] = "gitlab-redis"
+# redis['maxclients'] = "10000"
 # redis['uid'] = nil
 # redis['gid'] = nil
 

files/gitlab-cookbooks/gitlab/attributes/default.rb

@@ -383,6 +383,7 @@ default['gitlab']['redis']['shell'] = "/bin/nologin"
 default['gitlab']['redis']['home'] = "/var/opt/gitlab/redis"
 default['gitlab']['redis']['bind'] = '127.0.0.1'
 default['gitlab']['redis']['port'] = 0
+default['gitlab']['redis']['maxclients'] = "10000"
 default['gitlab']['redis']['password'] = nil
 default['gitlab']['redis']['unixsocket'] = "/var/opt/gitlab/redis/redis.socket"
 default['gitlab']['redis']['unixsocketperm'] = "777"

files/gitlab-cookbooks/gitlab/templates/default/redis.conf.erb

@@ -483,7 +483,7 @@ slave-priority 100
 # Once the limit is reached Redis will close all the new connections sending
 # an error 'max number of clients reached'.
 #
-# maxclients 10000
+maxclients <%= @maxclients %>
 
 # Don't use more memory than the specified amount of bytes.
 # When the memory limit is reached Redis will try to remove keys