Update: Configured docker-compose and Created 'wait_for_db' Django ma…

…nagement command

.github/workflows/checks.yml

@@ -16,6 +16,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Test
-        run: docker-compose run --rm app sh -c "python manage.py test"
+        run: docker-compose run --rm app sh -c "python manage.py wait_for_db &&
+                                                python manage.py test"
       - name: Lint
         run: docker-compose run --rm app sh -c "flake8"

app/app/settings.py

@@ -10,6 +10,7 @@
 https://docs.djangoproject.com/en/3.2/ref/settings/
 """
 
+import os
 from pathlib import Path
 
 # Build paths inside the project like this: BASE_DIR / 'subdir'.
@@ -37,6 +38,8 @@
     'django.contrib.sessions',
     'django.contrib.messages',
     'django.contrib.staticfiles',
+
+    'core',
 ]
 
 MIDDLEWARE = [
@@ -73,11 +76,23 @@
 # Database
 # https://docs.djangoproject.com/en/3.2/ref/settings/#databases
 
+# DATABASES = {
+#     'default': {
+#         'ENGINE': 'django.db.backends.sqlite3',
+#         'NAME': BASE_DIR / 'db.sqlite3',
+#     }
+# }
+
+
+# Setting Django to work with installed postgresql database
 DATABASES = {
-    'default': {
-        'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': BASE_DIR / 'db.sqlite3',
-    }
+  'default': {
+    'ENGINE': 'django.db.backends.postgresql',
+    'HOST': os.environ.get('DB_HOST'),
+    'NAME': os.environ.get('DB_NAME'),
+    'USER': os.environ.get('DB_USER'),
+    'PASSWORD': os.environ.get('DB_PASS'),
+  }
 }
 
 

app/core/admin.py

@@ -0,0 +1,3 @@
+from django.contrib import admin # noqa
+
+# Register your models here.

app/core/apps.py

@@ -0,0 +1,6 @@
+from django.apps import AppConfig
+
+
+class CoreConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'core'

app/core/management/commands/wait_for_db.py

@@ -0,0 +1,27 @@
+"""
+Django command to wait for the Database to become available.
+"""
+import time
+
+from psycopg2 import OperationalError as Psycopg2Error
+
+from django.core.management.base import BaseCommand
+from django.db.utils import OperationalError
+
+
+class Command(BaseCommand):
+    """Django command to wait for DB"""
+
+    def handle(self, *args, **options):
+        """Entry point for the 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

@@ -0,0 +1,3 @@
+from django.db import models # noqa
+
+# Create your models here.

app/core/tests/test_commands.py

@@ -0,0 +1,34 @@
+"""
+Test custom Django management commands
+"""
+from unittest.mock import patch
+
+from psycopg2 import OperationalError as Psycopg2Error
+
+from django.core.management import call_command
+from django.db.utils import OperationalError
+from django.test import SimpleTestCase
+
+
+@patch('core.management.commands.wait_for_db.Command.check')
+class TestCommands(SimpleTestCase):
+    """Testing Django commands"""
+
+    def test_wait_for_db_ready(self, patched_check):
+        """Test waiting for database to be ready"""
+        patched_check.return_value = True
+
+        call_command('wait_for_db')
+
+        patched_check.assert_called_once_with(databases=['default'])
+
+    @patch('time.sleep')
+    def test_wait_for_db_delay(self, patched_sleep, patched_check):
+        """Test waiting for database when getting OperationalError"""
+        patched_check.side_effect = [Psycopg2Error] * 2 + \
+                                    [OperationalError] * 3 + [True]
+
+        call_command('wait_for_db')
+
+        self.assertEqual(patched_check.call_count, 6)
+        patched_check.assert_called_with(databases=['default'])

docker-compose.yml

@@ -11,7 +11,9 @@ services:
     volumes:
       - "./app:/app"
     command: >
-      sh -c "python manage.py runserver 0.0.0.0:8000"
+      sh -c "python manage.py wait_for_db &&
+             python manage.py migrate &&
+             python manage.py runserver 0.0.0.0:8000"
     environment:
       - DB_HOST=db
       - DB_NAME=devdb