Fix KubernetesPodOperator pod name length validation (#8829)

* Fix KubernetesPodOperator pod name length validation

* Add test, verify Exception is raised

airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py

@@ -49,8 +49,8 @@ class KubernetesPodOperator(BaseOperator):  # pylint: disable=too-many-instance-
     :param image: Docker image you wish to launch. Defaults to hub.docker.com,
         but fully qualified URLS will point to custom repositories.
     :type image: str
-    :param name: name of the pod in which the task will run, will be used to
-        generate a pod id (DNS-1123 subdomain, containing only [a-z0-9.-]).
+    :param name: name of the pod in which the task will run, will be used (plus a random
+        suffix) to generate a pod id (DNS-1123 subdomain, containing only [a-z0-9.-]).
     :type name: str
     :param cmds: entrypoint of the container. (templated)
         The docker images's entrypoint is used if this is not provided.
@@ -322,5 +322,5 @@ class KubernetesPodOperator(BaseOperator):  # pylint: disable=too-many-instance-
     def _set_name(self, name):
         if self.pod_template_file or self.full_pod_spec:
             return None
-        validate_key(name, max_length=63)
+        validate_key(name, max_length=220)
         return re.sub(r'[^a-z0-9.-]+', '-', name.lower())

tests/runtime/kubernetes/test_kubernetes_pod_operator.py

@@ -819,5 +819,20 @@ class TestKubernetesPodOperator(unittest.TestCase):
         self.expected_pod['spec']['priorityClassName'] = priority_class_name
         self.assertEqual(self.expected_pod, actual_pod)
 
+    def test_pod_name(self):
+        pod_name_too_long = "a" * 221
+        with self.assertRaises(AirflowException):
+            KubernetesPodOperator(
+                namespace='default',
+                image="ubuntu:16.04",
+                cmds=["bash", "-cx"],
+                arguments=["echo 10"],
+                labels={"foo": "bar"},
+                name=pod_name_too_long,
+                task_id="task",
+                in_cluster=False,
+                do_xcom_push=False,
+            )
+
 
 # pylint: enable=unused-argument