Use geo_secondary_role to set tracking database connection properly

app/models/geo/base_registry.rb

 class Geo::BaseRegistry < ActiveRecord::Base
   self.abstract_class = true
 
-  if Gitlab::Geo.configured? && (Gitlab::Geo.secondary? || Rails.env.test?)
+  if Gitlab::Geo.secondary_role_enabled?
     establish_connection Rails.configuration.geo_database
   end
 end

config/gitlab.yml.example

@@ -622,6 +622,10 @@ production: &base
     #   host: localhost
     #   port: 3808
 
+  ## GitLab Geo settings (EE-only)
+  geo_secondary_role:
+    enable: false
+
   #
   # 5. Extra customization
   # ==========================
@@ -705,6 +709,8 @@ test:
         user_filter: ''
         group_base: 'ou=groups,dc=example,dc=com'
         admin_group: ''
+  geo_secondary_role:
+    enable: true
 
 staging:
   <<: *base

config/initializers/1_settings.rb

@@ -342,6 +342,8 @@ Settings.pages['external_https']  ||= false unless Settings.pages['external_http
 # Geo
 #
 Settings.gitlab['geo_status_timeout'] ||= 10
+Settings['geo_secondary_role'] ||= Settingslogic.new({})
+Settings.geo_secondary_role['enable'] = false if Settings.geo_secondary_role['enable'].nil?
 
 #
 # Git LFS

config/initializers/geo.rb

-if File.exist?(Rails.root.join('config/database_geo.yml'))
+if Gitlab::Geo.secondary_role_enabled?
   Rails.application.configure do
     config.geo_database = config_for(:database_geo)
   end

lib/gitlab/geo.rb

@@ -46,6 +46,10 @@ module Gitlab
       Rails.configuration.respond_to?(:geo_database)
     end
 
+    def self.secondary_role_enabled?
+      Gitlab.config.geo_secondary_role['enable']
+    end
+
     def self.license_allows?
       ::License.current&.feature_available?(:geo)
     end