What is the deference between prometheus and prometheusremotewrite as the exporter?

[koktlzz]

I used the example code to create metrics data and want to export them to prometheus. Here is my config.yaml:

receivers:
  otlp:
    protocols:
      grpc:
      http:

processors:
  batch:

exporters:
  prometheus:
    endpoint: "10.122.70.50:9090"
    namespace: "testapp"
service:
  pipelines:
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [prometheus]

But otel-collector service failed and no useful message in logs:

Sep 01 17:07:01 prometheus-1 systemd[1]: Started OpenTelemetry Collector.
Sep 01 17:07:01 prometheus-1 systemd[1]: Starting OpenTelemetry Collector...
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.657+0800        info        service/collector.go:303        Starting otelcol...        {"Version": "v0.33.0", "NumCPU": 4}
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.657+0800        info        service/collector.go:242        Loading configuration...
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.658+0800        info        service/collector.go:258        Applying configuration...
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.658+0800        info        builder/exporters_builder.go:264        Exporter was built.        {"kind": "exporter", "name": "prometheus"}
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.658+0800        info        builder/pipelines_builder.go:214        Pipeline was built.        {"pipeline_name": "metrics", "pipeline_datatype": "metrics"}
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.659+0800        info        builder/receivers_builder.go:227        Receiver was built.        {"kind": "receiver", "name": "otlp", "datatype": "metrics"}
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.659+0800        info        service/service.go:143        Starting extensions...
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.659+0800        info        builder/extensions_builder.go:54        Extension is starting...        {"kind": "extension", "name": "pprof"}
Sep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.659+0800        info        pprofextension/pprofextension.go:79        Starting net/http/pprof server        {"kind": "extension", "name": "pprof", "config": {"TCPAddr":{"Endpoint":"0.0.0.0:1777"},"BlockProfileFraction":0,"MutexProfileFrSep 01 17:07:01 prometheus-1 otelcol[98955]: 2021-09-01T17:07:01.660+0800        info        builder/extensions_builder.go:60        Extension started.        {"kind": "extension", "name": "pprof"}
Sep 01 17:07:01 prometheus-1 systemd[1]: otel-collector.service: main process exited, code=exited, status=1/FAILURE
Sep 01 17:07:01 prometheus-1 systemd[1]: Unit otel-collector.service entered failed state.
Sep 01 17:07:01 prometheus-1 systemd[1]: otel-collector.service failed.
Sep 01 17:07:01 prometheus-1 systemd[1]: otel-collector.service holdoff time over, scheduling restart.
Sep 01 17:07:01 prometheus-1 systemd[1]: start request repeated too quickly for otel-collector.service
Sep 01 17:07:01 prometheus-1 systemd[1]: Failed to start OpenTelemetry Collector.
Sep 01 17:07:01 prometheus-1 systemd[1]: Unit otel-collector.service entered failed state.
Sep 01 17:07:01 prometheus-1 systemd[1]: otel-collector.service failed.

However, if i use prometheusremotewrite as the expoter instead, it works well:

receivers:
  otlp:
    protocols:
      grpc:
      http:

processors:
  batch:

exporters:
  prometheusremotewrite:
    external_labels:
      namespace: "remote_write"
    endpoint: "http://10.122.70.50:9090/api/v1/write"
service:
  pipelines:
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [prometheusremotewrite]

So what is the deference between prometheus and prometheusremotewrite? Why the prometheus exporter failed?

[koktlzz]

Oh i realize that prometheus means export metrics and wait for any prometheus server pulling. The prometheusremotewrite means push the metrics to the specific prometheus server.