fix: handle PermissionError in init_log_folder for mounted filesystems

airflow-core/newsfragments/63878.bugfix.rst

@@ -0,0 +1 @@
+Fixed ``airflow`` CLI commands (including ``airflow db migrate``) crashing with ``PermissionError`` on startup when ``base_log_folder`` is configured to a path on a mounted filesystem (e.g. NFS) whose parent directories the Airflow user cannot create.

shared/logging/src/airflow_shared/logging/structlog.py

@@ -756,9 +756,15 @@ def init_log_folder(directory: str | os.PathLike[str], new_folder_permissions: i
     user.
     """
     directory = _PatchedPath(directory)
-    for parent in reversed(_PatchedPath(directory).parents):
-        parent.mkdir(mode=new_folder_permissions, exist_ok=True)
-    directory.mkdir(mode=new_folder_permissions, exist_ok=True)
+    try:
+        directory.mkdir(mode=new_folder_permissions, parents=True, exist_ok=True)
+    except OSError as e:
+        log.warning(
+            "Could not create log folder %s: %s. "
+            "Airflow will continue but logging to this directory may fail.",
+            directory,
+            e,
+        )
 
 
 def init_log_file(

shared/logging/tests/logging/test_structlog.py

@@ -25,6 +25,7 @@
 import sys
 import textwrap
 from datetime import datetime, timezone
+from pathlib import Path
 from unittest import mock
 
 import pytest
@@ -35,7 +36,7 @@
 from airflow_shared.logging import structlog as structlog_module
 from airflow_shared.logging.structlog import configure_logging
 
-# We don't want to use the caplog fixture in this test, as the main purpose of this file is to capture the
+# We avoid the caplog fixture for most tests here; the main purpose of this file is to capture the
 # _rendered_ output of the tests to make sure it is correct.
 
 PY_3_11 = sys.version_info >= (3, 11)
@@ -512,6 +513,14 @@ def spy(et, ev, tb):
         sys.excepthook = original
 
 
+def test_init_log_folder_does_not_raise_on_permission_error():
+    from airflow_shared.logging.structlog import init_log_folder
+
+    with mock.patch.object(Path, "mkdir", side_effect=PermissionError("not allowed")):
+        # Must not raise — CLI commands like `airflow db migrate` rely on this.
+        init_log_folder("/tmp/blocked", 0o775)
+
+
 class TestWarningsInterceptor:
     @pytest.fixture(autouse=True)
     def reset(self):