Load Geo DB only when Geo is enabled, and only if it is a secondary node

app/models/geo/base_registry.rb

 class Geo::BaseRegistry < ActiveRecord::Base
   self.abstract_class = true
 
-  establish_connection Rails.configuration.geo_database
+  if Gitlab::Geo.secondary?
+    establish_connection Rails.configuration.geo_database
+  end
 end

config/application.rb

@@ -158,5 +158,8 @@ module Gitlab
     config.generators do |g|
       g.factory_girl false
     end
+
+    # This is needed for GitLab Geo
+    config.assets.initialize_on_precompile = false
   end
 end

config/initializers/geo.rb

-Rails.application.configure do
-  config.geo_database = config_for(:database_geo)
+if Gitlab::Geo.secondary?
+  Rails.application.configure do
+    config.geo_database = config_for(:database_geo)
+  end
 end

config/initializers/health_check.rb

@@ -2,7 +2,9 @@ HealthCheck.setup do |config|
   config.standard_checks = %w(database migrations cache)
   config.full_checks = %w(database migrations cache)
 
-  config.add_custom_check('geo') do
-    Gitlab::Geo::HealthCheck.perform_checks
+  if Gitlab::Geo.secondary?
+    config.add_custom_check('geo') do
+      Gitlab::Geo::HealthCheck.perform_checks
+    end
   end
 end

lib/gitlab/geo.rb

@@ -19,7 +19,7 @@ module Gitlab
     end
 
     def self.enabled?
-      self.cache_value(:geo_node_enabled) { GeoNode.exists? }
+      self.cache_value(:geo_node_enabled) { self.connected_to_primary_db? && GeoNode.exists? }
     end
 
     def self.license_allows?
@@ -31,7 +31,7 @@ module Gitlab
     end
 
     def self.secondary?
-      self.cache_value(:geo_node_secondary) { self.enabled? && self.current_node && !self.current_node.primary? }
+      self.cache_value(:geo_node_secondary) { self.enabled? && self.current_node && self.current_node.secondary? }
     end
 
     def self.primary_ssh_path_prefix
@@ -80,5 +80,10 @@ module Gitlab
       # urlsafe_base64 may return a string of size * 4/3
       SecureRandom.urlsafe_base64(size)[0, size]
     end
+
+    def self.connected_to_primary_db?
+      ActiveRecord::Base.connection.active? &&
+        ActiveRecord::Base.connection.table_exists?(GeoNode.table_name)
+    end
   end
 end

lib/tasks/geo.rake

@@ -24,13 +24,19 @@ namespace :geo do
 
     # append and prepend proper tasks to all the tasks defined above
     ns.tasks.each do |task|
-      task.enhance ['geo:config:set'] do
+      task.enhance ['geo:config:check', 'geo:config:set'] do
         Rake::Task['geo:config:restore'].invoke
       end
     end
   end
 
   namespace :config do
+    task :check do
+      unless File.exist?(Rails.root.join('config/database_geo.yml'))
+        abort('You should run these tasks only when GitLab Geo is enabled, and only if it is a secondary node')
+      end
+    end
+
     task :set do
       # save current configuration
       @previous_config = {