From 5fb9a3e6c3f70bc615db2a1c2a7fde7b022703d6 Mon Sep 17 00:00:00 2001
From: Ludwig Behm <lbehm@users.noreply.github.com>
Date: Thu, 3 Feb 2022 01:17:27 +0100
Subject: [PATCH] pusher: add a /metrics.json endpoint

---
 pusher/src/Controller/PrometheusController.ts | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/pusher/src/Controller/PrometheusController.ts b/pusher/src/Controller/PrometheusController.ts
index 7fff3981..1ce106f1 100644
--- a/pusher/src/Controller/PrometheusController.ts
+++ b/pusher/src/Controller/PrometheusController.ts
@@ -2,6 +2,16 @@ import { App } from "../Server/sifrr.server";
 import { HttpRequest, HttpResponse } from "uWebSockets.js";
 import { register, collectDefaultMetrics } from "prom-client";
 
+interface IPrometheusValue {
+    labels: { [label: string]: string };
+    value: number;
+}
+interface IPrometheusMetric {
+    name: string;
+    help: string;
+    type: string;
+    values: Array<IPrometheusValue>;
+}
 export class PrometheusController {
     constructor(private App: App) {
         collectDefaultMetrics({
@@ -9,10 +19,36 @@ export class PrometheusController {
         });
 
         this.App.get("/metrics", this.metrics.bind(this));
+        this.App.get("/metrics.json", this.metricsAsJSON.bind(this));
     }
 
     private metrics(res: HttpResponse, req: HttpRequest): void {
         res.writeHeader("Content-Type", register.contentType);
         res.end(register.metrics());
     }
+    private async getAllMetrics() : Promise<IPrometheusMetric[]> {
+        return await Promise.all(
+            (register.getMetricsAsArray() as any[])
+                .map((metric) => metric.get() as Promise<IPrometheusMetric>));
+    }
+    private metricsAsJSON(res: HttpResponse, req: HttpRequest): void {
+        this.getAllMetrics().then((items) => {
+            let json : { [key : string] : number | { [label : string] : number } } = {};
+            for (const item of items) {
+                for (const value of item.values) {
+                    if (value.labels && Object.keys(value.labels).length > 0) {
+                        const key = Object.keys(value.labels)
+                                    .map((label) => label + ':' + value.labels[label]).join('|');
+                        const data : { [label : string] : number } = (json[item.name] as { [label : string] : number }) || { };
+                        data[key] = value.value;
+                        json[item.name] = data;
+                    } else {
+                        json[item.name] = value.value;
+                    }
+                }
+            }
+            res.writeHeader('Content-Type', 'application/json');
+            res.end(JSON.stringify(json));
+        });
+    }
 }