Implemented wait_for_db command and tests for it.

app/core/admin.py

@@ -1,3 +1,3 @@
-from django.contrib import admin
+from django.contrib import admin # noqa
 
 # Register your models here.

app/core/management/commands/wait_for_db.py

@@ -1,11 +1,27 @@
 """
 Django command to wait for the database to be available.
 """
+import time
+
+from psycopg2 import OperationalError as Psycopg2Error
+
+from django.db.utils import OperationalError
 from django.core.management.base import BaseCommand
 
 
 class Command(BaseCommand):
     """Django command to wait the database."""
 
     def handle(self, *args, **options):
-        pass 
+        """Entrypoint for command."""
+        self.stdout.write('Waiting for database...')
+        db_up = False
+        while db_up is False:
+            try:
+                self.check(databases=['default'])
+                db_up = True
+            except (Psycopg2Error, OperationalError):
+                self.stdout.write('Database unavailable, waiting 1 second...')
+                time.sleep(1)
+
+        self.stdout.write(self.style.SUCCESS('Database available!'))

app/core/models.py

@@ -1,3 +1,3 @@
-from django.db import models
+from django.db import models # noqa
 
 # Create your models here.

app/core/tests/test_commands.py

@@ -19,7 +19,7 @@ def test_wait_for_db_ready(self, patched_check):
         patched_check.return_value = True
 
         call_command('wait_for_db')
-        patched_check.assert_called_once_with(database=['default'])
+        patched_check.assert_called_once_with(databases=['default'])
 
     @patch('time.sleep')
     def test_wait_for_db_delay(self, patched_sleep, patched_check):
@@ -30,4 +30,4 @@ def test_wait_for_db_delay(self, patched_sleep, patched_check):
         call_command('wait_for_db')
 
         self.assertEqual(patched_check.call_count, 6)
-        patched_check.assert_called_with(database=['default'])
+        patched_check.assert_called_with(databases=['default'])