Allow PID file path to be relative when daemonize a process (scheduler, kerberos, etc) (#13232)

Closes #13200.

Currently, if the PID file path provided is relative,
the process silently fails to launch.

This fix ensures the PID path specified to be
a normalized absolutized path eventually (expand with cwd),
no matter the given value is relative or absolute.

(cherry picked from commit 93e4787b70)

airflow/utils/cli.py

@@ -227,8 +227,11 @@ def setup_locations(process, pid=None, stdout=None, stderr=None, log=None):
         stdout = os.path.join(settings.AIRFLOW_HOME, f'airflow-{process}.out')
     if not log:
         log = os.path.join(settings.AIRFLOW_HOME, f'airflow-{process}.log')
+
     if not pid:
         pid = os.path.join(settings.AIRFLOW_HOME, f'airflow-{process}.pid')
+    else:
+        pid = os.path.abspath(pid)
 
     return pid, stdout, stderr, log
 

tests/utils/test_cli_util.py

@@ -131,6 +131,23 @@ class TestCliUtil(unittest.TestCase):
         command = json.loads(command.replace("'", '"'))
         self.assertEqual(command, expected_command)
 
+    def test_setup_locations_relative_pid_path(self):
+        relative_pid_path = "fake.pid"
+        pid_full_path = os.path.join(os.getcwd(), relative_pid_path)
+        pid, _, _, _ = cli.setup_locations(process="fake_process", pid=relative_pid_path)
+        self.assertEqual(pid, pid_full_path)
+
+    def test_setup_locations_absolute_pid_path(self):
+        abs_pid_path = os.path.join(os.getcwd(), "fake.pid")
+        pid, _, _, _ = cli.setup_locations(process="fake_process", pid=abs_pid_path)
+        self.assertEqual(pid, abs_pid_path)
+
+    def test_setup_locations_none_pid_path(self):
+        process_name = "fake_process"
+        default_pid_path = os.path.join(settings.AIRFLOW_HOME, f"airflow-{process_name}.pid")
+        pid, _, _, _ = cli.setup_locations(process=process_name)
+        self.assertEqual(pid, default_pid_path)
+
 
 @contextmanager
 def fail_action_logger_callback():