Add commands sent statistic

Track RCON commands sent.

CHANGELOG.md

@@ -36,6 +36,7 @@ Version 2.0.0
 - Added config to specify which path the master interface is accessed under,
   allowing it to be proxied behind web-server.
 - Added WebSocket usage statistics.
+- Added commands sent statistic.
 
 ### Changes
 

slave.js

@@ -16,6 +16,12 @@ const luaTools = require('lib/luaTools');
 const config = require('lib/config');
 
 
+const instanceRconCommandsCounter = new prometheus.Counter(
+	"clusterio_instance_rcon_commands_total",
+	"How many commands have been sent to the instance",
+	{ labels: ["instance_id"] }
+);
+
 /**
  * Keeps track of the runtime parameters of an instance
  */
@@ -39,6 +45,12 @@ class Instance extends link.Link{
 			factorioDir, this._dir, serverOptions
 		);
 
+		let originalSendRcon = this.server.sendRcon;
+		this.server.sendRcon = (...args) => {
+			instanceRconCommandsCounter.labels(String(this.config.get("instance.id"))).inc();
+			return originalSendRcon.call(this.server, ...args);
+		}
+
 		this.server.on('output', (output) => {
 			link.messages.instanceOutput.send(this, { instance_id: this.config.get("instance.id"), output })