| PORT | 80 | Integer | The port opened by express.js inside the container |
| NODE_ENV | production | String | Is it a production of development version of the application |
| DB_NAME | robinson | String | The MongoDB database name |
| DB_USER | robinson | String | The MongoDB username |
| DB_PASSWORD | robinson123 | String | The MongoDB password |
| DB_HOST | mongo | String | The MongoDB host |
| SESSION_SECRET | pleaseChangeMe | String | |
| SESSION_SECURE | false | Boolean | Set to true if using behind HTTPs |
| HOST | localhost | String | |
| LOG_FOLDER | logs | String | |
| LOG_NAME | robinson | String | |
| LOG_LEVEL | info | String | |
| PROXY_ADDRESS | undefined | String | |
| RATE_LIMIT | 1000 | Integer | |
| GOOGLE_BOOKS_API_KEY | | String | Optional Google Books API key. When set, appended to ISBN lookup requests to use an authenticated quota and avoid rate limiting |