Ensure database is up before server start

app/server/management/commands/wait_for_db.py

@@ -0,0 +1,35 @@
+import sys
+import time
+
+from django.db import connection
+from django.db.utils import OperationalError
+from django.core.management.base import BaseCommand
+
+
+class Command(BaseCommand):
+    help = 'Blocks until the database is available'
+
+    def add_arguments(self, parser):
+        parser.add_argument('--poll_seconds', type=float, default=3)
+        parser.add_argument('--max_retries', type=int, default=60)
+
+    def handle(self, *args, **options):
+        max_retries = options['max_retries']
+        poll_seconds = options['poll_seconds']
+
+        for retry in range(max_retries):
+            try:
+                connection.ensure_connection()
+            except OperationalError as ex:
+                self.stdout.write(
+                    'Database unavailable on attempt {attempt}/{max_retries}:'
+                    ' {error}'.format(
+                        attempt=retry + 1,
+                        max_retries=max_retries,
+                        error=ex))
+                time.sleep(poll_seconds)
+            else:
+                break
+        else:
+            self.stdout.write(self.style.ERROR('Database unavailable'))
+            sys.exit(1)

tools/run.sh

@@ -4,5 +4,6 @@ set -o errexit
 
 if [[ ! -d "app/staticfiles" ]]; then python app/manage.py collectstatic --noinput; fi
 
+python app/manage.py wait_for_db
 python app/manage.py migrate
 gunicorn --bind="${BIND:-127.0.0.1:8000}" --workers="${WORKERS:-1}" --pythonpath=app app.wsgi