Improve settings.py

- Load database config from either config.yaml or environment variables
- Mix and match, if you want!
- Move to use logging module rather than just printing stuff
- Error if required database parameters are not required

InvenTree/config_template.yaml

@@ -1,22 +1,41 @@
 
 # Database backend selection - Configure backend database settings
-# Ref: https://docs.djangoproject.com/en/2.2/ref/settings/#std:setting-DATABASES
+# Ref: https://docs.djangoproject.com/en/dev/ref/settings/#std:setting-DATABASES
 # Specify database parameters below as they appear in the Django docs
+
+# Note: Database configuration options can also be specified from environmental variables,
+#       with the prefix INVENTREE_DB_
+#       e.g INVENTREE_DB_NAME / INVENTREE_DB_USER / INVENTREE_DB_PASSWORD
 database:
-  # Example configuration - sqlite (default)
-  ENGINE: django.db.backends.sqlite3
+  # Default configuration - sqlite filesystem database
+  ENGINE: sqlite3
   NAME: '../inventree_default_db.sqlite3' 
   
   # For more complex database installations, further parameters are required
   # Refer to the django documentation for full list of options
   
-  # Example Configuration - MySQL
+  # --- Available options: ---
+  # ENGINE: Database engine. Selection from:
+  #         - sqlite3
+  #         - mysql
+  #         - postgresql
+  # NAME: Database name
+  # USER: Database username (if required)
+  # PASSWORD: Database password (if required)
+  # HOST: Database host address (if required)
+  # PORT: Database host port (if required)
+
+  # --- Example Configuration - sqlite3 ---
+  # ENGINE: sqlite3
+  # NAME: '/path/to/database.sqlite3'
+
+  # --- Example Configuration - MySQL ---
   #ENGINE: django.db.backends.mysql
   #NAME: inventree
   #USER: inventree_username
   #PASSWORD: inventree_password
-  #HOST: ''
-  #PORT: ''
+  #HOST: '127.0.0.1'
+  #PORT: '5432'
 
 # Select default system language (default is 'en-us')
 language: en-us
@@ -45,6 +64,9 @@ debug: True
 #       and only if InvenTree is accessed from a local IP (127.0.0.1)
 debug_toolbar: False
 
+# Configure the system logging level
+# Options: DEBUG / INFO / WARNING / ERROR / CRITICAL
+log_level: WARNING
 
 # Allowed hosts (see ALLOWED_HOSTS in Django settings documentation)
 # A list of strings representing the host/domain names that this Django site can serve.