Fixes #28943 - pre-upgrade check to validate external DB version

definitions/checks/foreman/validate_external_db_version.rb

@@ -0,0 +1,28 @@
+module Checks
+  module Foreman
+    class ValidateExternalDbVersion < ForemanMaintain::Check
+      metadata do
+        description 'Make sure server is running on required database version'
+        tags :pre_upgrade
+        label :validate_external_db_version
+        confine do
+          feature(:foreman_database) && !feature(:foreman_database).local? &&
+            !check_min_version('foreman', '2.0')
+        end
+      end
+
+      def run
+        current_db_version = feature(:foreman_database).db_version
+        fail!(db_upgrade_message(current_db_version)) if current_db_version.major < 12
+      end
+
+      def db_upgrade_message(db_version)
+        product_name = feature(:instance).product_name
+
+        "\n\n*** ERROR: Server is running on PostgreSQL #{db_version} database.\n"\
+        "*** Newer version of #{product_name} supports only PostgreSQL version 12.\n"\
+        "*** Before proceeding further, you must upgrade database to PostgreSQL 12.\n"
+      end
+    end
+  end
+end

lib/foreman_maintain/concerns/base_database.rb

@@ -150,6 +150,17 @@ def dropdb(config = configuration)
         end
       end
 
+      def db_version(config = configuration)
+        if ping(config)
+          # Note - t removes headers, -A removes alignment whitespace
+          server_version_cmd = psql_command(config) + ' -c "SHOW server_version" -t -A'
+          version_string = execute!(server_version_cmd, :hidden_patterns => [config['password']])
+          version(version_string)
+        else
+          raise_service_error
+        end
+      end
+
       private
 
       def base_command(config, command = 'psql')