feat: setup database

Author: chandansgowda

Dockerfile

@@ -20,11 +20,15 @@ EXPOSE 8000
 ARG DEV=false
 RUN python -m venv /py && \
     /py/bin/pip install --upgrade pip && \
+    apk add --update --no-cache postgresql-client && \
+    apk add --update --no-cache --virtual .tmp-build-deps \
+        build-base postgresql-dev musl-dev && \
     /py/bin/pip install -r /tmp/requirements.txt && \
     if [ $DEV = "true" ]; \
         then /py/bin/pip install -r /tmp/requirements.dev.txt ; \
     fi && \
     rm -rf /tmp && \
+    apk del .tmp-build-deps && \
     adduser \
         --disabled-password \
         --no-create-home \

app/app/settings.py

@@ -9,7 +9,7 @@
 For the full list of settings and their values, see
 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 +37,7 @@
     'django.contrib.sessions',
     'django.contrib.messages',
     'django.contrib.staticfiles',
+    'core',
 ]
 
 MIDDLEWARE = [
@@ -75,8 +76,11 @@
 
 DATABASES = {
     'default': {
-        'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': BASE_DIR / 'db.sqlite3',
+        '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/__init__.py

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

app/core/admin.py

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

app/core/apps.py

@@ -0,0 +1,23 @@
+# Django command to wait for the database to be available
+from django.core.management.base import BaseCommand
+import time
+from psycopg2 import OperationalError as Psycopg2Error
+from django.db.utils import OperationalError
+
+
+class Command(BaseCommand):
+
+    def handle(self, *args, **options):
+        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(
+                    self.style.ERROR(
+                        'Database unavailable, waiting for 1 second...'))
+                time.sleep(1)
+
+        self.stdout.write(self.style.SUCCESS('Database available!'))

app/core/management/__init__.py

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

app/core/management/commands/__init__.py

@@ -0,0 +1,33 @@
+# Test custom Django management commands
+
+from unittest.mock import patch
+
+from psycopg2 import OperationalError as Psycopg2OpError
+
+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 CommandTests(SimpleTestCase):
+    """Test commands."""
+
+    def test_wait_for_db_ready(self, patched_check):
+        """Test waiting for database if database 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 = [Psycopg2OpError] * 2 + \
+            [OperationalError] * 3 + [True]
+
+        call_command('wait_for_db')
+
+        self.assertEqual(patched_check.call_count, 6)
+        patched_check.assert_called_with(databases=['default'])

app/core/management/commands/wait_for_db.py

@@ -1,2 +1,3 @@
 Django>=3.2.4,<3.3
 djangorestframework>=3.12.4,<3.13
+psycopg2>=2.8.6,<2.9