Question on how to use the library

[NancyXie2022]

Hi,
Our service is a GRPC service, and I am trying to use this library with prometheus to manage the metrics, I have tried to setup my code following the usage example, though it doesn't work, could you give me some suggestions on this?
My grpc server looks like:

var server: Server = null
var httpServer: HTTPServer = null
val pushRegistry = new CollectorRegistry()

def start(): Unit = {
val serverBuilder = if (config.auth.enableTls) {
val certPath = Paths.get(config.auth.serverCertFolder, config.auth.serverCertFilename).toString
val keyPath = Paths.get(config.auth.serverCertFolder, config.auth.serverCertKeyFilename).toString
if (config.auth.enableClientAuth) getSecureServerWithClientAuthBuilder(MuFnServer.port, certPath, keyPath, config.auth.trustStorePath)
else getSecureServerBuilder(MuFnServer.port, certPath, keyPath, config.auth.trustStorePath)
} else getInsecureServerBuilder(MuFnServer.port)

httpServer = new HTTPServer(9090)
server = serverBuilder
  .addService(MuFnServiceGrpc.bindService(new MuFnImpl(config, openTelemetry), executionContext))
  .addService(ProtoReflectionService.newInstance())
  .intercept(MonitoringServerInterceptor.create(Configuration.cheapMetricsOnly()
    .withCollectorRegistry(pushRegistry)))
  .build
  .start
sys.addShutdownHook {
  logger.error("*** shutting down gRPC server since JVM is shutting down")
  self.stop()
  logger.error("*** server shut down")
}

And my prometheus setup in pod-spec is as below:

template:
metadata:
annotations:
"prometheus.io/scrape": "true"
"prometheus.io/port": "8888"
"prometheus.io/path": "/metrics"
labels:
app.kubernetes.io/name: mufn-service
ginku.opentelemetry.onboard: "true"

[dinowernli]

Hi @NancyXie2022 , I'm having trouble following what you mean by "doesn't work". Could you clarify what behavior you're expecting to see, and what you're seeing instead?

[NancyXie2022]

hmm, I don't see metric get emitted, that what I mean it doesn't work.
I create a httpServer using port 9090,
I try to do this:
curl -v http://localhost:9090/metrics
there is no result though

curl -v http://localhost:9090/metrics

• About to connect() to localhost port 9090 (#0)
• Trying ::1...
• Connected to localhost (::1) port 9090 (#0)

GET /metrics HTTP/1.1
User-Agent: curl/7.29.0
Host: localhost:9090
Accept: /

< HTTP/1.1 200 OK
< Date: Thu, 08 Dec 2022 21:54:13 GMT
< Transfer-encoding: chunked
< Content-type: text/plain; version=0.0.4; charset=utf-8
<

• Connection #0 to host localhost left intact

[NancyXie2022]

@dinowernli thanks for your quick response

[NancyXie2022]

And also do you think my code is right or do you see anything wrong with it?

[dinowernli]

Looking at your code, I would expect the RPC server to correctly emit metrics into your pushRegistry object. I don't see you using it anywhere for serving via your metrics endpoint though. So I'm guessing you've got a missing step there to wire that up.

[NancyXie2022]

Hmm, do you mind how to make it serving via your metrics endpoint? Any example on that?

[dinowernli]

Assuming your HTTPServer is the one described here [1], then I think the missing piece might be to actually pass in your pushRegistry by calling .withRegistry(pushRegistry), see [2].

[1] https://github.com/prometheus/client_java/tree/7cf0cc9dc58981198be106a27333653bed7bf688#http
[2] https://github.com/prometheus/client_java/blob/7cf0cc9dc58981198be106a27333653bed7bf688/simpleclient_httpserver/src/main/java/io/prometheus/client/exporter/HTTPServer.java#L309