Merge branch 'sh-add-slave-status-check' into 'master'

Check for streaming replication in GeoNode status

See merge request !1481

doc/gitlab-geo/troubleshooting.md

@@ -55,6 +55,7 @@ your browser. We perform the following health checks on each secondary node
 to help identify if something is wrong:
 
 - Is the node running?
+- Is the node's secondary database configured for streaming replication?
 - Is the node's secondary tracking database configured?
 - Is the node's secondary tracking database connected?
 - Is the node's secondary tracking database up-to-date?

lib/gitlab/geo/health_check.rb

@@ -4,6 +4,7 @@ module Gitlab
       def self.perform_checks
         return '' unless Gitlab::Geo.secondary?
         return 'The Geo database configuration file is missing.' unless Gitlab::Geo.configured?
+        return 'The Geo node has a database that is not configured for streaming replication with the primary node.' unless self.database_secondary?
 
         database_version  = self.get_database_version.to_i
         migration_version = self.get_migration_version.to_i
@@ -48,6 +49,14 @@ module Gitlab
 
         latest_migration
       end
+
+      def self.database_secondary?
+        raise NotImplemented unless Gitlab::Database.postgresql?
+
+        ActiveRecord::Base.connection.execute('SELECT pg_is_in_recovery()')
+          .first
+          .fetch('pg_is_in_recovery') == 't'
+      end
     end
   end
 end

spec/lib/gitlab/geo/health_check_spec.rb

@@ -12,6 +12,14 @@ describe Gitlab::Geo::HealthCheck do
       expect(subject.perform_checks).to be_blank
     end
 
+    it 'returns an error when database is not configured for streaming replication' do
+      allow(Gitlab::Geo).to receive(:secondary?) { true }
+      allow(Gitlab::Database).to receive(:postgresql?) { true }
+      allow(ActiveRecord::Base).to receive_message_chain(:connection, :execute, :first, :fetch) { 'f' }
+
+      expect(subject.perform_checks).not_to be_blank
+    end
+
     it 'returns an error when configuration file is missing for tracking DB' do
       allow(Rails.configuration).to receive(:respond_to?).with(:geo_database) { false }