prometheus exporter seems not work as expected

[idrissneumann]

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Problem

According to this documentation if we manage to transform data into this kind of JSON payloads:

{
  "metric": {
    "gauge": {
      "value": 1.5
    },
    "kind": "absolute",
    "name": "memory_rss",
    "namespace": "app",
    "tags": {
      "host": "my-host.local"
    }
  }
}

The prometheus exporter should automatically transform this into openmetrics format printed on an http endpoint that can be scrapped by prometheus instances.

However, we tried this configuration of sinks:

sinks:
  out:
    type: "console"
    inputs:
       - remap_nagios_metrics
    encoding:
      codec: "json"
    target: "stdout"
  nagios_metrics:
    type: "prometheus_exporter"
    inputs:
      - remap_nagios_metrics
    address: 0.0.0.0:9598
    default_namespace: "ems"
    buffer:
      type: "memory"

The stdout output seems to comply with the expected payload format:

$ docker-compose up --force-recreate
vector  | {"metric":{"gauge":{"value":3.0},"kind":"absolute","name":"my_alert","tags":{"file":"/data/nagios.log","host":"xxxxxx","kind":"SERVICE ALERT","status":"OK","type":"SOFT","vector_host":"yyyyyyy"}}}
vector  | {"metric":{"gauge":{"value":1.0},"kind":"absolute","name":"my_alert","tags":{"file":"/data/nagios.log","host":"xxxxxx","kind":"SERVICE ALERT","status":"WARNING","type":"HARD","vector_host":"yyyyyyy"}}}
vector  | {"metric":{"gauge":{"value":1.0},"kind":"absolute","name":"my_alert","tags":{"file":"/data/nagios.log","host":"xxxxxx","kind":"SERVICE ALERT","status":"WARNING","type":"SOFT","vector_host":"yyyyyyy"}}}
vector  | {"metric":{"gauge":{"value":2.0},"kind":"absolute","name":"my_alert","tags":{"file":"/data/nagios.log","host":"xxxxxx","kind":"SERVICE ALERT","status":"WARNING","type":"SOFT","vector_host":"yyyyyyy"}}}
vector  | {"metric":{"gauge":{"value":3.0},"kind":"absolute","name":"my_alert","tags":{"file":"/data/nagios.log","host":"xxxxxx","kind":"SERVICE ALERT","status":"OK","type":"SOFT","vector_host":"yyyyyyy"}}}

But when I reach the http://localhost:9598/metrics route, I have an empty response without any metrics.

Thanks for your help

Configuration

sinks:
  out:
    type: "console"
    inputs:
       - remap_nagios_metrics
    encoding:
      codec: "json"
    target: "stdout"
  nagios_metrics:
    type: "prometheus_exporter"
    inputs:
      - remap_nagios_metrics
    address: 0.0.0.0:9598
    default_namespace: "ems"
    buffer:
      type: "memory"

Version

timberio/vector:0.44.0-distroless-libc