[exporters/prometheus] / [exporters/prometheusremotewrite] do not add _total suffix to Sum metric types

[povilasv]

Describe the bug

Currently exporters/prometheus and exporters/prometheusremotewrite do not add _total suffix metric for OpenTelemetry Sum type Metrics.

The spec states:

Ref: https://opentelemetry.io/docs/reference/specification/metrics/datamodel/#sums-1

Steps to reproduce

Openetelemtry collector exports the following metric in its :8888/metrics telemetry endpoint:

otelcol_exporter_enqueue_failed_metric_points{exporter="prometheus",...}

When it converts from Prometheus to OTel and then back to Prometheus it should become:

otelcol_exporter_enqueue_failed_metric_points_total{exporter="prometheus",...}

Because the counter is converted to Otel SUM Type:

A Prometheus Counter MUST be converted to an OTLP Sum with is_monotonic equal to true. If the counter has a _total suffix, it MUST be removed.

What did you expect to see?

Sum type metrics having _total suffix.

What did you see instead?

No _total suffix.

What version did you use?
Version: 877066b

What config did you use?

config:
  exporters:
    prometheus:
      endpoint: "0.0.0.0:9090"
    prometheusremotewrite:
      endpoint: "http://prometheus:9090/api/v1/write"
  extensions:
    health_check: {}
    memory_ballast: {}
  processors:
    batch: {}
    memory_limiter: null
  
  receivers:
    otlp:
      protocols:
        grpc:
          endpoint: 0.0.0.0:4417
          include_metadata: true
        http:
          endpoint: 0.0.0.0:4318
    prometheus:
      config:
        scrape_configs:
        - job_name: 'otelcol'
          scrape_interval: 10s
          static_configs:
          - targets: ['0.0.0.0:8888']

Environment

Additional context
Add any other context about the problem here.

[povilasv]

The other question is if this is intentional in the spec or not?

If the Prometheus metric never had the _total suffix and we do Prometheus -> Otelp -> Prometheus, it will add it.

[povilasv]

Folks let me know if you agree and have any feedback, I can work on a fix -> #11838 👯‍♂️

[TylerHelmuth]

pinging @Aneurysm9 as code owner

[paivagustavo]

@dashpole This is a duplicate of #8950.

@povilasv this was added by #10028 under the --feature-gates=pkg.translator.prometheus.NormalizeName featuregate.

[dashpole]

I need to double-check, but we should probably flip that feature-gate to enabled by default.

[povilasv]

closing as it's duplicate issue of #8950