Add support for loading config values from environment variables

CHANGELOG.md

@@ -4,6 +4,8 @@
 * **Change default configuration format to .ini**
   * Existing `config.json` files will continue to work and will not be deprecated
   * This makes the default configuration format for the bot much more approachable than JSON
+* Config values can now also be loaded from environment variables
+  (see [Configuration](docs/configuration.md#environment-variables) for more details)
 * New rewritten instructions for setting up and using the bot
 * New easy-to-use `start.bat` file for Windows
 * Update several package dependencies

docs/configuration.md

@@ -7,6 +7,7 @@ Haven't set up the bot yet? Check out [Setting up the bot](setup.md) first!
 - [Required options](#required-options)
 - [Other options](#other-options)
 - [config.ini vs config.json](#configini-vs-configjson)
+- [Environment variables](#environment-variables)
 
 ## Configuration file
 All bot options are saved in a configuration file in the bot's folder.
@@ -313,3 +314,23 @@ by escaping the newline with a backslash (`\ `):
 This is the second line of the greeting."
 }
 ```
+
+## Environment variables
+Config options can be passed via environment variables.
+
+To get the name of the corresponding environment variable for an option, convert the option to SNAKE_CASE with periods
+being replaced by two underscores and add `MM_` as a prefix. If adding multiple values for the same option, separate the
+values with two pipe characters: `||`.
+
+Examples:
+* `mainGuildId` -> `MM_MAIN_GUILD_ID`
+* `commandAliases.mv` -> `MM_COMMAND_ALIASES__MV`
+* From:  
+  ```ini
+  inboxServerPermission[] = kickMembers
+  inboxServerPermission[] = manageMessages
+  ```  
+  To:  
+  `MM_INBOX_SERVER_PERMISSION=kickMembers||manageMessages`
+
+The `port` option also accepts the environment variable `PORT` without a prefix, but `MM_PORT` takes precedence.

src/config.js

@@ -137,17 +137,21 @@ for (const [key, value] of Object.entries(process.env)) {
     .replace(/([a-z])_([a-z])/g, (m, m1, m2) => `${m1}${m2.toUpperCase()}`)
     .replace('__', '.');
 
-  userConfig[configKey] = process.env[key];
+  userConfig[configKey] = value.includes('||')
+    ? value.split('||')
+    : value;
+
+  loadedEnvValues++;
+}
+
+if (process.env.PORT && !process.env.MM_PORT) {
+  // Special case: allow common "PORT" environment variable without prefix
+  userConfig.port = process.env.PORT;
   loadedEnvValues++;
 }
 
 if (loadedEnvValues > 0) {
-  console.log(`Loaded ${loadedEnvValues} values from environment variables`);
-}
-
-if (process.env.PORT) {
-  // Special case: allow common "PORT" environment variable without prefix
-  userConfig.port = process.env.PORT;
+  console.log(`Loaded ${loadedEnvValues} ${loadedEnvValues === 1 ? 'value' : 'values'} from environment variables`);
 }
 
 // Convert config keys with periods to objects