Track deployments in Prometheus

src/controllers/metrics.ts

@@ -1,9 +1,14 @@
 import { register } from 'prom-client';
 
 import { AppController } from '@/app.ts';
-import { dbAvailableConnectionsGauge, dbPoolSizeGauge } from '@/metrics.ts';
+import { githash } from '@/git.ts';
+import { dbAvailableConnectionsGauge, dbPoolSizeGauge, deploymentsCounter } from '@/metrics.ts';
 import { Storages } from '@/storages.ts';
 
+if (githash) {
+  deploymentsCounter.inc({ git_hash: githash });
+}
+
 /** Prometheus/OpenMetrics controller. */
 export const metricsController: AppController = async (c) => {
   const db = await Storages.database();

src/git.ts

@@ -0,0 +1,11 @@
+let githash: string | undefined;
+
+try {
+  const cmd = new Deno.Command('git', { args: ['rev-parse', 'HEAD'] });
+  const out = await cmd.output();
+  githash = new TextDecoder().decode(out.stdout).trim();
+} catch {
+  //
+}
+
+export { githash };

src/metrics.ts

@@ -1,5 +1,11 @@
 import { Counter, Gauge, Histogram } from 'prom-client';
 
+export const deploymentsCounter = new Counter({
+  name: 'ditto_deployments_total',
+  help: 'Updated on each deployment',
+  labelNames: ['git_hash'],
+});
+
 export const httpRequestsCounter = new Counter({
   name: 'ditto_http_requests_total',
   help: 'Total number of HTTP requests',