add env variable support

server.mjs

@@ -3,10 +3,17 @@ import Monitor from './monitor.mjs';
 
 (async () => {
 	let configFile = 'config.json';
+
+	//命令行参数支持，格式：npm start -- my_config.json
     if (process.argv.length >= 3) {
         configFile = process.argv[2];
     }
 
+    //环境变量支持，格式：CONFIGFILE=my_config.json pm2 start server.mjs
+    if (typeof(process.env.CONFIGFILE) != 'undefined') {
+        configFile = process.env.CONFIGFILE;
+    }
+
     let monitor = new Monitor(configFile);
     await monitor.init();
 })();