fix: prometheus multproc dir permissions error (#120)

* os.chmod to force permissions

* Clear all files and dirs inside of multiproc dir instead of the dir itself

* Only clear if it exists

* Only clear subdirs

* Fix circular import

* Only remove directories beginning with

* Try setting mode to 0o777 manually on creating dir

* Try replicating the permissions used by mkdtemp

* Use `gettempdir`

* Remove all prometheus setup from python

* Blindly add code from gpt 😬

* Tidy up gpt code...

* Move to gunicorn conf.py

* move back to main.py and refactor into prometheus.utils

* Add pragma no cover

* Fix issue with settings being accessed at import time

* Remove type ignore

* Improve docstring

* Revert all logic to `core`

* Remove `chmod`

* Use try/except

* Tidy up

* Add pragma no cover

Author: matthewelwell

src/common/core/constants.py

@@ -1 +1 @@
-DEFAULT_PROMETHEUS_MULTIPROC_DIR = "/tmp/flagsmith-prometheus"
+DEFAULT_PROMETHEUS_MULTIPROC_DIR_NAME = "flagsmith-prometheus"

src/common/core/main.py

@@ -1,16 +1,17 @@
 import contextlib
 import logging
 import os
-import shutil
 import sys
 import typing
+from tempfile import gettempdir
 
 from django.core.management import (
     execute_from_command_line as django_execute_from_command_line,
 )
 
 from common.core.cli import healthcheck
-from common.core.constants import DEFAULT_PROMETHEUS_MULTIPROC_DIR
+from common.core.constants import DEFAULT_PROMETHEUS_MULTIPROC_DIR_NAME
+from common.core.utils import clear_directory, make_writable_directory
 
 logger = logging.getLogger(__name__)
 
@@ -35,6 +36,15 @@ def ensure_cli_env() -> typing.Generator[None, None, None]:
 
     # TODO @khvn26 Move logging setup to here
 
+    # Prometheus multiproc support
+    prom_dir = os.environ.setdefault(
+        "PROMETHEUS_MULTIPROC_DIR",
+        os.path.join(gettempdir(), DEFAULT_PROMETHEUS_MULTIPROC_DIR_NAME),
+    )
+    if os.path.exists(prom_dir):
+        clear_directory(prom_dir)
+    make_writable_directory(prom_dir)
+
     # Currently we don't install Flagsmith modules as a package, so we need to add
     # $CWD to the Python path to be able to import them
     sys.path.append(os.getcwd())
@@ -43,18 +53,6 @@ def ensure_cli_env() -> typing.Generator[None, None, None]:
     # without resorting to it being set outside of the application
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings.dev")
 
-    # Set up Prometheus' multiprocess mode
-    prometheus_multiproc_dir_name = os.environ.setdefault(
-        "PROMETHEUS_MULTIPROC_DIR",
-        DEFAULT_PROMETHEUS_MULTIPROC_DIR,
-    )
-    shutil.rmtree(prometheus_multiproc_dir_name, ignore_errors=True)
-    os.makedirs(prometheus_multiproc_dir_name, exist_ok=True)
-    logger.info(
-        "Re-created %s for Prometheus multi-process mode",
-        prometheus_multiproc_dir_name,
-    )
-
     if "docgen" in sys.argv:
         os.environ["DOCGEN_MODE"] = "true"
 

src/common/core/utils.py

@@ -1,7 +1,9 @@
 import json
 import logging
+import os
 import pathlib
 import random
+import shutil
 from functools import lru_cache
 from itertools import cycle
 from typing import (
@@ -198,3 +200,30 @@ def using_database_replica(
         return manager
 
     return manager.db_manager(chosen_replica)
+
+
+def clear_directory(directory_path: str) -> None:
+    """
+    Safely clear a directory including all subdirectories and files.
+    """
+    for p in pathlib.Path(directory_path).rglob("*"):
+        try:
+            # Ensure that the cleanup doesn't silently fail on
+            # files and subdirs created by other users.
+            p.chmod(0o777)
+        except (PermissionError, FileNotFoundError):  # pragma: no cover
+            pass
+
+    shutil.rmtree(directory_path, ignore_errors=True)
+
+
+def make_writable_directory(directory_path: str) -> None:
+    os.makedirs(directory_path, exist_ok=True)
+
+    try:
+        # While `mkdir` sets mode=0o777 by default, this can be affected by umask
+        # resulting in lesser permissions for other users. This step ensures the
+        # directory is writable for all users.
+        os.chmod(directory_path, 0o777)
+    except PermissionError:  # pragma: no cover
+        pass