Add support for loading config values from environment variables. Fix nested/object values in config.ini.

src/config.js

@@ -35,11 +35,8 @@ for (const configFile of configFiles) {
   } catch (e) {}
 }
 
-if (! foundConfigFile) {
-  throw new Error(`Could not find a config file!`);
-}
-
 // Load config file
+if (foundConfigFile) {
   console.log(`Loading configuration from ${foundConfigFile}...`);
   try {
     if (foundConfigFile.endsWith('.js')) {
@@ -55,6 +52,10 @@ try {
   } catch (e) {
     throw new Error(`Error reading config file! The error given was: ${e.message}`);
   }
+}
+
+const required = ['token', 'mailGuildId', 'mainGuildId', 'logChannelId'];
+const numericOptions = ['requiredAccountAge', 'requiredTimeOnServer', 'smallAttachmentLimit', 'port'];
 
 const defaultConfig = {
   "token": null,
@@ -122,9 +123,53 @@ const defaultConfig = {
   "logDir": path.join(__dirname, '..', 'logs'),
 };
 
-const required = ['token', 'mailGuildId', 'mainGuildId', 'logChannelId'];
+// Load config values from environment variables
-const numericOptions = ['requiredAccountAge', 'requiredTimeOnServer', 'smallAttachmentLimit', 'port'];
+const envKeyPrefix = 'MM_';
+let loadedEnvValues = 0;
 
+for (const [key, value] of Object.entries(process.env)) {
+  if (! key.startsWith(envKeyPrefix)) continue;
+
+  // MM_CLOSE_MESSAGE -> closeMessage
+  // MM_COMMAND_ALIASES__MV => commandAliases.mv
+  const configKey = key.slice(envKeyPrefix.length)
+    .toLowerCase()
+    .replace(/([a-z])_([a-z])/g, (m, m1, m2) => `${m1}${m2.toUpperCase()}`)
+    .replace('__', '.');
+
+  userConfig[configKey] = process.env[key];
+  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;
+}
+
+// Convert config keys with periods to objects
+// E.g. commandAliases.mv -> commandAliases: { mv: ... }
+for (const [key, value] of Object.entries(userConfig)) {
+  if (! key.includes('.')) continue;
+
+  const keys = key.split('.');
+  let cursor = userConfig;
+  for (let i = 0; i < keys.length; i++) {
+    if (i === keys.length - 1) {
+      cursor[keys[i]] = value;
+    } else {
+      cursor[keys[i]] = cursor[keys[i]] || {};
+      cursor = cursor[keys[i]];
+    }
+  }
+
+  delete userConfig[key];
+}
+
+// Combine user config with default config to form final config
 const finalConfig = Object.assign({}, defaultConfig);
 
 for (const [prop, value] of Object.entries(userConfig)) {