gatewayUrl is undefined when i register url in pushgateway

[skls1337]

PromService .ts

import { Injectable, OnModuleInit, Logger } from '@nestjs/common';
import * as client from 'prom-client';

@Injectable()
export class PromService implements OnModuleInit {
  private readonly logger = new Logger(PromService.name);

  constructor(private readonly pushgateway: client.Pushgateway<any>) {}

  onModuleInit() {
    this.logger.log('Pushing to prometheus gateway');
    console.log(this.pushgateway);
  }
}

PromModule.ts

import { Module } from '@nestjs/common';
import { PrometheusModule } from '@willsoto/nestjs-prometheus';

import { Pushgateway } from 'prom-client';
import { PromService } from 'src/common/services/pushgateway.service';

@Module({
  imports: [
    PrometheusModule.register({
      defaultMetrics: {
        enabled: true,
        config: {
          prefix: 'backforfront_',
        },
      },
      pushgateway: {
        url: process.env.PUSHGATEWAY_URL,
      },
    }),
  ],
  providers: [PromService, Pushgateway],
  exports: [PromService, Pushgateway],
})
export class PromModule {}

Log from console on startup

Pushgateway {
2024-08-08 13:00:33   registry: Registry {
2024-08-08 13:00:33     _metrics: {
2024-08-08 13:00:33       backforfront_process_cpu_user_seconds_total: [Counter],
2024-08-08 13:00:33       backforfront_process_cpu_system_seconds_total: [Counter],
2024-08-08 13:00:33       backforfront_process_cpu_seconds_total: [Counter],
2024-08-08 13:00:33       backforfront_process_start_time_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_process_resident_memory_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_process_virtual_memory_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_process_heap_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_process_open_fds: [Gauge],
2024-08-08 13:00:33       backforfront_process_max_fds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_min_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_max_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_mean_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_stddev_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_p50_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_p90_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_eventloop_lag_p99_seconds: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_resources: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_resources_total: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_handles: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_handles_total: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_requests: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_active_requests_total: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_heap_size_total_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_heap_size_used_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_external_memory_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_heap_space_size_total_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_heap_space_size_used_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_heap_space_size_available_bytes: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_version_info: [Gauge],
2024-08-08 13:00:33       backforfront_nodejs_gc_duration_seconds: [Histogram]
2024-08-08 13:00:33     },
2024-08-08 13:00:33     _collectors: [],
2024-08-08 13:00:33     _defaultLabels: {},
2024-08-08 13:00:33     _contentType: 'text/plain; version=0.0.4; charset=utf-8'
2024-08-08 13:00:33   },
2024-08-08 13:00:33   gatewayUrl: undefined,
2024-08-08 13:00:33   requireJobName: true,
2024-08-08 13:00:33   requestOptions: {}
2024-08-08 13:00:33 }

Yes, my env is defined, there is already an issue closed on this topic, what am I doing wrong?

[willsoto]

I think you are clobbering the Pushgateway registered by this module with your own:

import { Pushgateway } from 'prom-client';

providers: [PromService, Pushgateway],

Remove the unnecessary registration and see if it works.

[skls1337]

I tried your suggestion and I have the same behaviour.

I found out that when you init the module the gatewayUrl is undefined and forcing it to get a value fixes the connection to pushgateway. So maybe something is not going well here

onModuleInit() {
    this.logger.log('Pushing to prometheus gateway');
    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
    // @ts-ignore
    this.pushgateway.gatewayUrl = 'http://pushgateway:9091';
    this.pushgateway.push({
      jobName: 'backforfront',
    });
  }

[willsoto]

Yes, my env is defined,

can you hardcode it and see if you get the same result?

[skls1337]

Can confirm with the env hardcoded that the gatewayUrl will come up as undefined, and if I do the this.pushgateway.push() I receive TypeError: The "url" argument must be of type string. Received undefined

[willsoto]

Yeah not sure what to tell you, I have a test that proves it works. Maybe the reference is being lost in the way you are importing...I would definitely not have that additional Pushgateway provider registered though as that isn't necessary.

[skls1337]

Sure, I checked the tests and it proves it works. If I completely remove the onModuleInit it goes fine, but for some reason, I can't query Prometheus with my metrics for my nestjs service

[skls1337]

Hi, I found out I can fix my problem with registerAsync

PrometheusModule.registerAsync({
      useFactory: () => {
        return {
          pushgateway: {
            url: process.env.PUSHGATEWAY_URL,
          },
        };
      },
    }),

So this can conclude my fix to the issue I had. Thx for the support!