Add Factorio CPU and Memory usage statistics

Add per instance metrics for CPU and memory usage with the pidusage
library.

CHANGELOG.md

@@ -37,6 +37,7 @@ Version 2.0.0
   allowing it to be proxied behind web-server.
 - Added WebSocket usage statistics.
 - Added commands sent statistic.
+- Added Factorio server CPU and memory usage statistic.
 
 ### Changes
 

lib/factorio/server.js

@@ -590,6 +590,16 @@ class FactorioServer extends events.EventEmitter {
 		return this._version;
 	}
 
+	/**
+	 * The pid of the server process, or null if not running
+	 */
+	get pid() {
+		if (!this._server) {
+			return null;
+		}
+		return this._server.pid;
+	}
+
 	_attachStdio() {
 		this._server.stdout.on('data', chunk => { this._stdout.data(chunk); });
 		this._server.stdout.on('close', () => { this._stdout.end(); });

package.json

@@ -54,6 +54,7 @@
     "needle": "^2.4.0",
     "node-factorio-api": "^0.3.8",
     "node-forge": "^0.7.1",
+    "pidusage": "^2.0.18",
     "rcon-client": "^4.2.0",
     "request": "^2.83.0",
     "sanitizer": "^0.1.3",

slave.js

@@ -2,6 +2,7 @@ const fs = require('fs-extra');
 const path = require('path');
 const yargs = require("yargs");
 const events = require("events");
+const pidusage = require("pidusage");
 const version = require("./package").version;
 
 // internal libraries
@@ -22,6 +23,18 @@ const instanceRconCommandsCounter = new prometheus.Counter(
 	{ labels: ["instance_id"] }
 );
 
+const instanceFactorioCpuTime = new prometheus.Gauge(
+	"clusterio_instance_factorio_cpu_time_total",
+	"Factorio CPU time spent in seconds.",
+	{ labels: ["instance_id"] }
+);
+
+const instanceFactorioMemoryUsage = new prometheus.Gauge(
+	"clusterio_instance_factorio_resident_memory_bytes",
+	"Factorio resident memory size in bytes.",
+	{ labels: ["instance_id"] }
+);
+
 /**
  * Keeps track of the runtime parameters of an instance
  */
@@ -311,6 +324,13 @@ class Instance extends link.Link{
 			}
 		}
 
+		let pid = this.server.pid;
+		if (pid) {
+			let stats = await pidusage(pid);
+			instanceFactorioCpuTime.labels(String(this.config.get("instance.id"))).set(stats.ctime / 1000);
+			instanceFactorioMemoryUsage.labels(String(this.config.get("instance.id"))).set(stats.memory);
+		}
+
 		return { results };
 	}
 
@@ -702,6 +722,9 @@ class Slave extends link.Link {
 		}
 		this.connector.close(1001, "Slave Shutdown");
 		await events.once(this.connector, "close");
+
+		// Clear silly interval in pidfile library.
+		pidusage.clear();
 	}
 }