Add setting to control Rails.application.config.hosts

Signed-off-by: Balasankar "Balu" C <balasankar@gitlab.com>

changelogs/unreleased/add-rails-application-config-hosts.yml

+---
+title: Add setting to control Rails.application.config.hosts
+merge_request: 55491
+author:
+type: added

config/gitlab.yml.example

@@ -73,6 +73,8 @@ production: &base
         worker_src: "'self' blob:"
         report_uri:
 
+    allowed_hosts: []
+
     # Trusted Proxies
     # Customize if you have GitLab behind a reverse proxy which is running on a different machine.
     # Add the IP address for your reverse proxy to the list, otherwise users will appear signed in from that address.

config/initializers/1_settings.rb

@@ -210,6 +210,7 @@ Settings.gitlab['domain_allowlist'] ||= []
 Settings.gitlab['import_sources'] ||= Gitlab::ImportSources.values
 Settings.gitlab['trusted_proxies'] ||= []
 Settings.gitlab['content_security_policy'] ||= Gitlab::ContentSecurityPolicy::ConfigLoader.default_settings_hash
+Settings.gitlab['allowed_hosts'] ||= []
 Settings.gitlab['no_todos_messages'] ||= YAML.load_file(Rails.root.join('config', 'no_todos_messages.yml'))
 Settings.gitlab['impersonation_enabled'] ||= true if Settings.gitlab['impersonation_enabled'].nil?
 Settings.gitlab['usage_ping_enabled'] = true if Settings.gitlab['usage_ping_enabled'].nil?

config/initializers/rails_host_authorization.rb

@@ -2,6 +2,11 @@
 
 # This file requires config/initializers/1_settings.rb
 
+if Gitlab.config.gitlab.allowed_hosts.present?
+  Rails.application.config.hosts << Gitlab.config.gitlab.host << 'unix'
+  Rails.application.config.hosts += Gitlab.config.gitlab.allowed_hosts
+end
+
 if Rails.env.development?
   Rails.application.config.hosts += [Gitlab.config.gitlab.host, 'unix', 'host.docker.internal']