Limit pod_name length to HOST_NAME_MAX

airflow/providers/cncf/kubernetes/kubernetes_helper_functions.py

@@ -34,6 +34,8 @@
 
 alphanum_lower = string.ascii_lowercase + string.digits
 
+POD_NAME_MAX_LENGTH = 63  # Matches Linux kernel's HOST_NAME_MAX default value minus 1.
+
 
 def rand_str(num):
     """Generate random lowercase alphanumeric string of length num.
@@ -43,7 +45,7 @@ def rand_str(num):
     return "".join(secrets.choice(alphanum_lower) for _ in range(num))
 
 
-def add_pod_suffix(*, pod_name: str, rand_len: int = 8, max_len: int = 80) -> str:
+def add_pod_suffix(*, pod_name: str, rand_len: int = 8, max_len: int = POD_NAME_MAX_LENGTH) -> str:
     """Add random string to pod name while staying under max length.
 
     :param pod_name: name of the pod
@@ -59,16 +61,12 @@ def create_pod_id(
     dag_id: str | None = None,
     task_id: str | None = None,
     *,
-    max_length: int = 80,
+    max_length: int = POD_NAME_MAX_LENGTH,
     unique: bool = True,
 ) -> str:
     """
     Generate unique pod ID given a dag_id and / or task_id.
 
-    The default of 80 for max length is somewhat arbitrary, mainly a balance between
-    content and not overwhelming terminal windows of reasonable width. The true
-    upper limit is 253, and this is enforced in construct_pod.
-
     :param dag_id: DAG ID
     :param task_id: Task ID
     :param max_length: max number of characters

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

@@ -51,6 +51,7 @@
     convert_volume_mount,
 )
 from airflow.providers.cncf.kubernetes.hooks.kubernetes import KubernetesHook
+from airflow.providers.cncf.kubernetes.kubernetes_helper_functions import POD_NAME_MAX_LENGTH
 from airflow.providers.cncf.kubernetes.pod_generator import PodGenerator
 from airflow.providers.cncf.kubernetes.triggers.pod import KubernetesPodTrigger
 from airflow.providers.cncf.kubernetes.utils import xcom_sidecar  # type: ignore[attr-defined]
@@ -92,7 +93,7 @@ def _rand_str(num):
     return "".join(secrets.choice(alphanum_lower) for _ in range(num))
 
 
-def _add_pod_suffix(*, pod_name, rand_len=8, max_len=253):
+def _add_pod_suffix(*, pod_name, rand_len=8, max_len=POD_NAME_MAX_LENGTH):
     """Add random string to pod name while staying under max len.
 
     TODO: when min airflow version >= 2.5, delete this function and import from kubernetes_helper_functions.
@@ -107,7 +108,7 @@ def _create_pod_id(
     dag_id: str | None = None,
     task_id: str | None = None,
     *,
-    max_length: int = 80,
+    max_length: int = POD_NAME_MAX_LENGTH,
     unique: bool = True,
 ) -> str:
     """
@@ -962,7 +963,7 @@ def build_pod_request_obj(self, context: Context | None = None) -> k8s.V1Pod:
 
         if not pod.metadata.name:
             pod.metadata.name = _create_pod_id(
-                task_id=self.task_id, unique=self.random_name_suffix, max_length=80
+                task_id=self.task_id, unique=self.random_name_suffix, max_length=POD_NAME_MAX_LENGTH
             )
         elif self.random_name_suffix:
             # user has supplied pod name, we're just adding suffix

airflow/providers/cncf/kubernetes/pod_generator.py

@@ -41,7 +41,11 @@
     AirflowException,
     RemovedInAirflow3Warning,
 )
-from airflow.providers.cncf.kubernetes.kubernetes_helper_functions import add_pod_suffix, rand_str
+from airflow.providers.cncf.kubernetes.kubernetes_helper_functions import (
+    POD_NAME_MAX_LENGTH,
+    add_pod_suffix,
+    rand_str,
+)
 from airflow.providers.cncf.kubernetes.pod_generator_deprecated import (
     PodDefaults,
     PodGenerator as PodGeneratorDeprecated,
@@ -380,11 +384,11 @@ def construct_pod(
             - executor_config
             - dynamic arguments
         """
-        if len(pod_id) > 253:
+        if len(pod_id) > POD_NAME_MAX_LENGTH:
             warnings.warn(
-                "pod_id supplied is longer than 253 characters; truncating and adding unique suffix."
+                f"pod_id supplied is longer than {POD_NAME_MAX_LENGTH} characters; truncating and adding unique suffix."
             )
-            pod_id = add_pod_suffix(pod_name=pod_id, max_len=253)
+            pod_id = add_pod_suffix(pod_name=pod_id, max_len=POD_NAME_MAX_LENGTH)
         try:
             image = pod_override_object.spec.containers[0].image  # type: ignore
             if not image:

tests/providers/cncf/kubernetes/operators/test_pod.py

@@ -1347,7 +1347,7 @@ def test_task_id_as_name_with_suffix_very_long(self):
         pod = k.build_pod_request_obj({})
         assert (
             re.match(
-                r"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-[a-z0-9]{8}",
+                r"a{54}-[a-z0-9]{8}",
                 pod.metadata.name,
             )
             is not None

tests/providers/cncf/kubernetes/test_kubernetes_helper_functions.py

@@ -87,14 +87,14 @@ def test_create_pod_id_dag_and_task(self, dag_id, task_id, expected, create_pod_
 
     def test_create_pod_id_dag_too_long_with_suffix(self, create_pod_id):
         actual = create_pod_id("0" * 254)
-        assert len(actual) == 80
-        assert re.match(r"0{71}-[a-z0-9]{8}", actual)
+        assert len(actual) == 63
+        assert re.match(r"0{54}-[a-z0-9]{8}", actual)
         assert re.match(pod_name_regex, actual)
 
     def test_create_pod_id_dag_too_long_non_unique(self, create_pod_id):
         actual = create_pod_id("0" * 254, unique=False)
-        assert len(actual) == 80
-        assert re.match(r"0{80}", actual)
+        assert len(actual) == 63
+        assert re.match(r"0{63}", actual)
         assert re.match(pod_name_regex, actual)
 
     @pytest.mark.parametrize("unique", [True, False])

tests/providers/cncf/kubernetes/test_pod_generator.py

@@ -572,7 +572,7 @@ def test_ensure_max_identifier_length(self, mock_rand_str):
             base_worker_pod=worker_config,
         )
 
-        assert result.metadata.name == "a" * 244 + "-" + self.rand_str
+        assert result.metadata.name == "a" * 54 + "-" + self.rand_str
         for v in result.metadata.labels.values():
             assert len(v) <= 63