Merge pull request #928 from to-sta/wait_for_db

added custom management command wait_for_db

backend/backend/management/commands/wait_for_db.py

@@ -0,0 +1,39 @@
+import sys
+import time
+from argparse import ArgumentParser
+from typing import TypedDict, Unpack
+
+from django.core.management.base import BaseCommand
+from django.db import connection
+from django.db.utils import OperationalError
+
+
+class Options(TypedDict):
+    poll_seconds: float
+    max_retries: int
+
+
+class Command(BaseCommand):
+    help = "Wait until the database is available"
+
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        parser.add_argument("--poll_seconds", type=float, default=2)
+        parser.add_argument("--max_retries", type=int, default=30)
+
+    def handle(self, *args: str, **options: Unpack[Options]) -> None:
+        poll_seconds = options["poll_seconds"]
+        max_retries = options["max_retries"]
+
+        for retry in range(max_retries):
+            try:
+                connection.ensure_connection()
+            except OperationalError as error:
+                self.stdout.write(
+                    f"Database unavailable on attempt {retry + 1}/{max_retries}: {error}"
+                )
+                time.sleep(poll_seconds)
+            else:
+                break
+        else:
+            self.stdout.write(self.style.ERROR("Database unavailable"))
+            sys.exit(1)

backend/backend/settings.py

@@ -56,6 +56,7 @@
     "django.contrib.sessions",
     "django.contrib.messages",
     "django.contrib.staticfiles",
+    "backend",
     "authentication",
     "entities",
     "content",

backend/pyproject.toml

@@ -68,6 +68,7 @@ exclude = [
     "entities/factories.py",
     "events/factories.py",
 ]
+enable_incomplete_feature = ["Unpack"]
 
 [[tool.mypy.overrides]]
 module = ["authentication.*", "content.*", "entities.*", "events.*"]

docker-compose.yml

@@ -8,7 +8,8 @@ services:
       context: ./backend
     container_name: django_backend
     restart: unless-stopped
-    command: sh -c "python manage.py makemigrations &&
+    command: sh -c "python manage.py wait_for_db &&
+      python manage.py makemigrations &&
       python manage.py migrate &&
       python manage.py loaddata fixtures/superuser.json &&
       python manage.py loaddata fixtures/status_types.json &&