Ensure internal api command get the "ready" prefix on start (#38550)

This prefix is used by _get_num_ready_workers_running to determine num workers ready.

airflow/api_internal/gunicorn_config.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+#
+# 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 __future__ import annotations
+
+import setproctitle
+
+from airflow import settings
+
+
+def post_worker_init(_):
+    """
+    Set process title.
+
+    This is used by airflow.cli.commands.internal_api_command to track the status of the worker.
+    """
+    old_title = setproctitle.getproctitle()
+    setproctitle.setproctitle(settings.GUNICORN_WORKER_READY_PREFIX + old_title)

airflow/cli/commands/internal_api_command.py

@@ -115,6 +115,8 @@ def internal_api(args):
             str(access_logfile),
             "--error-logfile",
             str(error_logfile),
+            "--config",
+            "python:airflow.api_internal.gunicorn_config",
         ]
 
         if args.access_logformat and args.access_logformat.strip():

tests/cli/commands/test_internal_api_command.py

@@ -205,6 +205,8 @@ def test_cli_internal_api_args(self):
                     "-",
                     "--error-logfile",
                     "-",
+                    "--config",
+                    "python:airflow.api_internal.gunicorn_config",
                     "--access-logformat",
                     "custom_log_format",
                     "airflow.cli.commands.internal_api_command:cached_app()",