add metrics for startup and file cache counts

spec/server_test.js

@@ -36,6 +36,9 @@ describe('Manifest service', () => {
     process.env.CACHE_TTL = 30000
   })
 
+  // Some say, this is not necessary to test
+  // But failing startups due to code errors in the probes will cause this to not work
+  // Therefore, we should keep this
   it('is healthy', async () => {
     const response = await request(app).get('/healthy')
     expect(response.statusCode).toBe(200)

src/createApp.js

@@ -13,6 +13,7 @@ import health from '@cloudnative/health-connect'
 
 // Prometheus middleware for standard api metrics
 import promBundle from 'express-prom-bundle'
+import promClient from 'prom-client'
 
 // Swagger UI for api-docs
 import swaggerUi from 'swagger-ui-express'
@@ -26,6 +27,11 @@ const swaggerDocument = yaml.load(fs.readFileSync('./src/swagger.yaml', 'utf8'))
 const bypass = (request) => ignorePaths.includes(request.path)
 const metricsMiddleware = promBundle({ bypass, includePath: true })
 
+const startUpTimeGauge = new promClient.Gauge({
+  name: 'manifest_service_startup_time',
+  help: 'Time to warm up cache'
+})
+
 export function createApp () {
   // The app returned by express() is in fact a JavaScript Function, designed to be passed to Node’s HTTP servers as a callback to handle requests.
 
@@ -36,6 +42,7 @@ export function createApp () {
 
   const healthCheck = new health.HealthChecker()
   const startupCheck = new health.StartupCheck('warmup cache', async function () {
+    const stopTimer = startUpTimeGauge.startTimer()
     try {
       const viteManifests = await loadViteManifests()
       const deps = viteManifestToDeps(viteManifests)
@@ -43,6 +50,8 @@ export function createApp () {
     } catch (e) {
       logger.error(`Failed to get dependencies: ${e.message}`)
       throw e
+    } finally {
+      stopTimer()
     }
   })
   healthCheck.registerStartupCheck(startupCheck)

src/files.js

 import fetch from 'node-fetch'
 import crypto from 'crypto'
 import { config } from './config.js'
+import promClient from 'prom-client'
+import { getLogger } from './logger.js'
 
 async function fetchData (path, baseUrl) {
   const response = await fetch(new URL(path, baseUrl))
@@ -13,6 +15,15 @@ async function fetchData (path, baseUrl) {
     content
   }]
 }
+
+const fileCounter = new promClient.Counter({
+  name: 'manifest_service_file_cache_fetches',
+  help: 'Number of fetched files'
+})
+const fileErrorCounter = new promClient.Counter({
+  name: 'manifest_service_file_cache_fetch_errors',
+  help: 'Number of errors while fetching files'
+})
 class FileCache {
   constructor () {
     this._cache = {}
@@ -32,13 +43,17 @@ class FileCache {
               (m?.css?.indexOf(file) >= 0)
             )
             if (!manifest) {
-              console.error('could not find manifest for', file)
+              getLogger().error('could not find manifest for', file)
               return null
             }
             return await fetchData(file, manifest.meta.baseUrl)
-          } catch (e) { console.error(e) }
+          } catch (e) {
+            fileErrorCounter.inc()
+            getLogger().error(e)
+          }
         }))).filter(data => Array.isArray(data) && data.length === 2))
       }
+      fileCounter.inc(result.length)
       return result
     }()))
     this._cache = cache