Add upgrade rule to check for mesos executor and flag to change it. (a…

…pache#11528)

* add upgrade rule to check for mesos config and flag to remove it.

* change from checking the mesos config section to core/executor config

* remove leading new line and indent in desc

(cherry picked from commit 6739b53)

airflow/upgrade/rules/mesos_executor_removed.py

@@ -0,0 +1,36 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from airflow.upgrade.rules.base_rule import BaseRule
+from airflow.configuration import conf
+
+
+class MesosExecutorRemovedRule(BaseRule):
+    """
+    MesosExecutorRemovedRule class to ease upgrade to Airflow 2.0
+    """
+    title = "Removal of Mesos Executor"
+    description = "The Mesos Executor has been deprecated as it was not widely used and not maintained."
+
+    def check(self):
+        executor_key = conf.get(section="core", key="executor")
+        if executor_key == "MesosExecutor":
+            return (
+                "The Mesos Executor has been deprecated as it was not widely used and not maintained."
+                "Please migrate to any of the supported executors."
+                "See https://airflow.apache.org/docs/stable/executor/index.html for more details."
+            )

tests/upgrade/rules/test_mesos_executor_removed.py

@@ -0,0 +1,48 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from unittest import TestCase
+
+from airflow.upgrade.rules.mesos_executor_removed import MesosExecutorRemovedRule
+from tests.test_utils.config import conf_vars
+
+
+class TestMesosExecutorRemovedRule(TestCase):
+    @conf_vars({("core", "executor"): "MesosExecutor"})
+    def test_invalid_check(self):
+        rule = MesosExecutorRemovedRule()
+
+        assert isinstance(rule.description, str)
+        assert isinstance(rule.title, str)
+
+        msg = (
+            "The Mesos Executor has been deprecated as it was not widely used and not maintained."
+            "Please migrate to any of the supported executors."
+            "See https://airflow.apache.org/docs/stable/executor/index.html for more details."
+        )
+
+        response = rule.check()
+        assert response == msg
+
+    @conf_vars({("core", "executor"): "SequentialExecutor"})
+    def test_check(self):
+        rule = MesosExecutorRemovedRule()
+
+        assert isinstance(rule.description, str)
+        assert isinstance(rule.title, str)
+
+        response = rule.check()
+        assert response is None