From 371d0c206fa58acecd161f21ac91337210126275 Mon Sep 17 00:00:00 2001
From: Andrew Farries <andrew@gitpod.io>
Date: Mon, 31 Oct 2022 16:56:26 +0000
Subject: [PATCH] Add imageBuildsCompletedTotal metric

Add a counter to track the number of image builds recorded as completed
by `server`, broken down by outcome (succeeded, failed).
---
 components/server/src/prometheus-metrics.ts          | 11 +++++++++++
 components/server/src/workspace/workspace-starter.ts | 10 ++++++++++
 2 files changed, 21 insertions(+)

diff --git a/components/server/src/prometheus-metrics.ts b/components/server/src/prometheus-metrics.ts
index 9f06939a359779..2637e60a8ea0d9 100644
--- a/components/server/src/prometheus-metrics.ts
+++ b/components/server/src/prometheus-metrics.ts
@@ -21,6 +21,7 @@ export function registerServerMetrics(registry: prometheusClient.Registry) {
     registry.registerMetric(prebuildsStartedTotal);
     registry.registerMetric(stripeClientRequestsCompletedDurationSeconds);
     registry.registerMetric(imageBuildsStartedTotal);
+    registry.registerMetric(imageBuildsCompletedTotal);
 }
 
 const loginCounter = new prometheusClient.Counter({
@@ -175,3 +176,13 @@ export const imageBuildsStartedTotal = new prometheusClient.Counter({
 export function increaseImageBuildsStartedTotal() {
     imageBuildsStartedTotal.inc();
 }
+
+export const imageBuildsCompletedTotal = new prometheusClient.Counter({
+    name: "gitpod_server_image_builds_completed_total",
+    help: "counter of the total number of image builds recorded as completed on server",
+    labelNames: ["outcome"],
+});
+
+export function increaseImageBuildsCompletedTotal(outcome: "succeeded" | "failed") {
+    imageBuildsCompletedTotal.inc({ outcome });
+}
diff --git a/components/server/src/workspace/workspace-starter.ts b/components/server/src/workspace/workspace-starter.ts
index 4deb4fb8fd958b..f2b0f230478ecb 100644
--- a/components/server/src/workspace/workspace-starter.ts
+++ b/components/server/src/workspace/workspace-starter.ts
@@ -114,6 +114,7 @@ import { ExtendedUser } from "@gitpod/ws-manager/lib/constraints";
 import {
     FailedInstanceStartReason,
     increaseFailedInstanceStartCounter,
+    increaseImageBuildsCompletedTotal,
     increaseImageBuildsStartedTotal,
     increaseSuccessfulInstanceStartCounter,
 } from "../prometheus-metrics";
@@ -1280,6 +1281,10 @@ export class WorkspaceStarter {
                 // ...and wait for the build to finish
                 buildResult = await result.buildPromise;
                 if (buildResult.getStatus() == BuildStatus.DONE_FAILURE) {
+                    // Register a failed image build only if the image actually needed to be built; ie the build was not a no-op.
+                    if (result.actuallyNeedsBuild) {
+                        increaseImageBuildsCompletedTotal("failed");
+                    }
                     throw new Error(buildResult.getMessage());
                 }
             } catch (err) {
@@ -1302,6 +1307,11 @@ export class WorkspaceStarter {
                 }
             }
 
+            // Register a successful image build only if the image actually needed to be built; ie the build was not a no-op.
+            if (result.actuallyNeedsBuild) {
+                increaseImageBuildsCompletedTotal("succeeded");
+            }
+
             // We have just found out how our base image is called - remember that.
             // Note: it's intentional that we overwrite existing baseImageNameResolved values here so that one by one the refs here become absolute (i.e. digested form).
             //       This prevents the "rebuilds" for old workspaces.