Automatically plug database via env vars

project/database.py

@@ -0,0 +1,29 @@
+import os
+
+from django.conf import settings
+
+
+engines = {
+    'sqlite': 'django.db.backends.sqlite3',
+    'postgresql': 'django.db.backends.postgresql_psycopg2',
+    'mysql': 'django.db.backends.mysql',
+}
+
+
+def config():
+    service_name = os.getenv('DATABASE_SERVICE_NAME')
+    if service_name:
+        engine = engines.get(os.getenv('DATABASE_ENGINE'), engines['sqlite'])
+    else:
+        engine = engines['sqlite']
+    name = os.getenv('DATABASE_NAME')
+    if not name and engine == engines['sqlite']:
+        name = os.path.join(settings.BASE_DIR, 'db.sqlite3')
+    return {
+        'ENGINE': engine,
+        'NAME': name,
+        'USER': os.getenv('DATABASE_USER'),
+        'PASSWORD': os.getenv('DATABASE_PASSWORD'),
+        'HOST': os.getenv('{}_SERVICE_HOST'.format(service_name)),
+        'PORT': os.getenv('{}_SERVICE_PORT'.format(service_name)),
+    }

project/settings.py

@@ -81,23 +81,10 @@ WSGI_APPLICATION = 'project.wsgi.application'
 # Database
 # https://docs.djangoproject.com/en/1.8/ref/settings/#databases
 
-if os.getenv("DATABASE_SERVICE_HOST"):
+from . import database
+
 DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.postgresql_psycopg2',
-            'NAME': os.getenv("DATABASE_NAME"),
-            'USER': os.getenv("DATABASE_USER"),
-            'PASSWORD': os.getenv("DATABASE_PASSWORD"),
-            'HOST': os.getenv("DATABASE_SERVICE_HOST"),
-            'PORT': os.getenv("DATABASE_SERVICE_PORT"),
-        }
-    }
-else:
-    DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.sqlite3',
-            'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
-        }
+    'default': database.config()
 }