Use env variables for Unicorn memory limits

This makes it easier for users to use their own limits based on their
server configuration.

config.ru

@@ -7,8 +7,11 @@ if defined?(Unicorn)
     # Unicorn self-process killer
     require 'unicorn/worker_killer'
 
+    min = (ENV['GITLAB_UNICORN_MEMORY_MIN'] || 200 * 1 << 20).to_i
+    max = (ENV['GITLAB_UNICORN_MEMORY_MAX'] || 250 * 1 << 20).to_i
+
     # Max memory size (RSS) per worker
-    use Unicorn::WorkerKiller::Oom, (200 * (1 << 20)), (250 * (1 << 20))
+    use Unicorn::WorkerKiller::Oom, min, max
   end
 end
 

doc/administration/environment_variables.md

@@ -17,6 +17,8 @@ DATABASE_URL | url | For example: postgresql://localhost/blog_development?pool=5
 GITLAB_EMAIL_FROM | email | Email address used in the "From" field in mails sent by GitLab
 GITLAB_EMAIL_DISPLAY_NAME | string | Name used in the "From" field in mails sent by GitLab
 GITLAB_EMAIL_REPLY_TO | email | Email address used in the "Reply-To" field in mails sent by GitLab
+GITLAB_UNICORN_MEMORY_MIN | integer | The minimum memory threshold (in bytes) for the Unicorn worker killer
+GITLAB_UNICORN_MEMORY_MAX | integer | The maximum memory threshold (in bytes) for the Unicorn worker killer
 
 ## Complete database variables