feat: use OT metrics instead of prom-client

Signed-off-by: blam <ben@blam.sh>

packages/backend-tasks/package.json

@@ -36,12 +36,12 @@
     "@backstage/config": "workspace:^",
     "@backstage/errors": "workspace:^",
     "@backstage/types": "workspace:^",
+    "@opentelemetry/api": "^1.3.0",
     "@types/luxon": "^3.0.0",
     "cron": "^2.0.0",
     "knex": "^2.0.0",
     "lodash": "^4.17.21",
     "luxon": "^3.0.0",
-    "prom-client": "^14.0.1",
     "uuid": "^8.0.0",
     "winston": "^3.2.1",
     "zod": "^3.21.4"

packages/backend-tasks/src/tasks/TaskWorker.ts

@@ -18,13 +18,12 @@ import { ConflictError, NotFoundError } from '@backstage/errors';
 import { CronTime } from 'cron';
 import { Knex } from 'knex';
 import { DateTime, Duration } from 'luxon';
-import { Counter, Summary } from 'prom-client';
 import { v4 as uuid } from 'uuid';
 import { Logger } from 'winston';
 import { DbTasksRow, DB_TASKS_TABLE } from '../database/tables';
-import { createCounterMetric, createSummaryMetric } from './metrics';
 import { TaskFunction, TaskSettingsV2, taskSettingsV2Schema } from './types';
 import { delegateAbortController, nowPlus, sleep } from './util';
+import { metrics, Counter, Histogram } from '@opentelemetry/api';
 
 const DEFAULT_WORK_CHECK_FREQUENCY = Duration.fromObject({ seconds: 5 });
 
@@ -35,7 +34,7 @@ const DEFAULT_WORK_CHECK_FREQUENCY = Duration.fromObject({ seconds: 5 });
  */
 export class TaskWorker {
   private readonly counter: Counter;
-  private readonly duration: Summary;
+  private readonly duration: Histogram;
 
   constructor(
     private readonly taskId: string,
@@ -44,15 +43,13 @@ export class TaskWorker {
     private readonly logger: Logger,
     private readonly workCheckFrequency: Duration = DEFAULT_WORK_CHECK_FREQUENCY,
   ) {
-    this.counter = createCounterMetric({
-      name: 'backstage_task_runs_total',
-      help: 'Total number of times a task has been run',
-      labelNames: ['task_id', 'result'],
+    const meter = metrics.getMeter('default');
+    this.counter = meter.createCounter('backend_task_runs_total', {
+      description: 'Total number of times a task has been run',
     });
-    this.duration = createSummaryMetric({
-      name: 'backstage_task_run_duration_seconds',
-      help: 'Duration of task runs in seconds',
-      labelNames: ['task_id', 'result'],
+    this.duration = meter.createHistogram('backend_task_run_duration', {
+      description: 'Histogram of task run durations',
+      unit: 'seconds',
     });
   }
 
@@ -66,7 +63,7 @@ export class TaskWorker {
     this.logger.info(
       `Task worker starting: ${this.taskId}, ${JSON.stringify(settings)}`,
     );
-    this.counter.inc({ task_id: this.taskId, result: 'started' }, 1);
+    this.counter.add(1, { task_id: this.taskId, result: 'started' });
 
     let attemptNum = 1;
     (async () => {
@@ -80,11 +77,13 @@ export class TaskWorker {
           }
 
           while (!options?.signal?.aborted) {
-            const endDuration = this.duration.startTimer();
+            const startTime = process.hrtime();
             const runResult = await this.runOnce(options?.signal);
-            endDuration({ task_id: this.taskId, result: 'completed' });
+            const delta = process.hrtime(startTime);
+            const endTime = delta[0] + delta[1] / 1e9;
 
-            this.counter.inc({ task_id: this.taskId, result: 'completed' }, 1);
+            this.duration.record(endTime, { task_id: this.taskId });
+            this.counter.add(1, { task_id: this.taskId, result: 'completed' });
 
             if (runResult.result === 'abort') {
               break;
@@ -94,7 +93,6 @@ export class TaskWorker {
           }
 
           this.logger.info(`Task worker finished: ${this.taskId}`);
-
           attemptNum = 0;
           break;
         } catch (e) {
@@ -102,7 +100,7 @@ export class TaskWorker {
           this.logger.warn(
             `Task worker failed unexpectedly, attempt number ${attemptNum}, ${e}`,
           );
-          this.counter.inc({ task_id: this.taskId, result: 'failed' }, 1);
+          this.counter.add(1, { task_id: this.taskId, result: 'failed' });
           await sleep(Duration.fromObject({ seconds: 1 }));
         }
       }

yarn.lock

@@ -3622,13 +3622,13 @@ __metadata:
     "@backstage/config": "workspace:^"
     "@backstage/errors": "workspace:^"
     "@backstage/types": "workspace:^"
+    "@opentelemetry/api": ^1.3.0
     "@types/cron": ^2.0.0
     "@types/luxon": ^3.0.0
     cron: ^2.0.0
     knex: ^2.0.0
     lodash: ^4.17.21
     luxon: ^3.0.0
-    prom-client: ^14.0.1
     uuid: ^8.0.0
     wait-for-expect: ^3.0.2
     winston: ^3.2.1