fix logic on using remote mysql db. make sqlite the fall back, logic clears up if not all variables are set

Dockerfile

@@ -4,10 +4,6 @@ MAINTAINER Jeffrey Forman <code@jeffreyforman.net>
 
 ENV DEBIAN_FRONTEND noninteractive
 
-# Uncomment the following line to not use a remote database,
-# and to use a local Sqlite database file.
-# ENV NODB 1
-
 RUN apt-get update \
      && rm -rf /var/lib/apt/lists/*
 

binder/settings.py

@@ -1,7 +1,10 @@
 # Django settings for binder project.
+import logging
 import os
 from django.contrib.messages import constants as messages
 
+logger = logging.getLogger(__name__)
+
 SITE_ROOT = os.path.dirname(os.path.realpath(__file__))
 DEBUG = True
 ADMINS = (
@@ -12,25 +15,31 @@ MANAGERS = ADMINS
 
 ALLOWED_HOSTS=['*']
 
-if os.getenv('NODB'):
+DB_NAME = os.environ.get('DJANGO_DB_NAME', 'binder')
-    print "Attempting to use Sqlite database at %s" % (os.path.join(SITE_ROOT, 'db') + '/binder.db')
+DB_USER = os.environ.get('DJANGO_DB_USER', None)
+DB_PASSWORD = os.environ.get('DJANGO_DB_PASSWORD', None)
+DB_HOST = os.environ.get('DJANGO_DB_HOST', None)
+
+if all([DB_NAME, DB_USER, DB_PASSWORD, DB_HOST]):
+    logger.info("Using MySQL server for data backend.")
+    DATABASES = {
+        'default': {
+            'ENGINE': 'django.db.backends.mysql',
+            'NAME': DB_NAME,
+            'USER': DB_USER,
+            'PASSWORD': DB_PASSWORD,
+            'HOST': DB_HOST,
+            'PORT': 3306,
+        }
+    }
+else:
+    logger.info("Using Sqlite database at %s" % (os.path.join(SITE_ROOT, 'db') + '/binder.db'))
     DATABASES = {
         'default': {
             'ENGINE': 'django.db.backends.sqlite3',
             'NAME': os.path.join(SITE_ROOT, 'db') + '/binder.db',
         }
     }
-else:
-    DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.mysql',
-            'NAME': os.environ.get('DJANGO_DB_NAME', 'binder'),
-            'USER': os.environ.get('DJANGO_DB_USER', ''),
-            'PASSWORD': os.environ.get('DJANGO_DB_PASSWORD', ''),
-            'HOST': os.environ.get('DJANGO_DB_HOST', ''),
-            'PORT': 3306,
-        }
-    }
 
 TIME_ZONE = 'America/New_York'