[mdatagen] Underscores in anchor tag in metadata key semantic_convention: ref: url causes generation error

[osullivandonal]

Component(s)

cmd/mdatagen

What happened?

Describe the bug

When using the optional key semantic_convention: in the metadata.yaml schema and running make generate, for example in otel-collector-contrib (this uses mdatagen), an error is thrown if there is an underscore in the anchor tag in the ref url.

Steps to reproduce

• Using make generate in otel-collector-contrib`
• Using this valid semantic conventions url:

https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time

Causes this error:

Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
make[1]: *** [../../../../../Makefile.Common:264: mdatagen] Error 1
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper'
internal/scraper/diskscraper/doc.go:4: running "make": exit status 2

What did you expect to see?

We expect the generation to complete without any errors

What did you see instead?

An error occured:

Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
make[1]: *** [../../../../../Makefile.Common:264: mdatagen] Error 1
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper'
internal/scraper/diskscraper/doc.go:4: running "make": exit status 2

Fix

This should be a simple fix, in cmd/mdatagen/internal/metrics.go we have:

var reNonAlnum = regexp.MustCompile(`[^a-z0-9]+`)

To fix the issue we just have to add an underscore to the regexp:

var reNonAlnum = regexp.MustCompile(`[^a-z0-9_]+`)

Collector version

a810b2d6fd4bc738e4570243409dce3fb148a5b7

Environment information

Environment

OS: (Operating System: Arch Linux, Kernel: Linux 6.17.9-arch1-1)
Compiler(go version go1.25.5 X:nodwarf5 linux/amd64)

OpenTelemetry Collector configuration

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318
  hostmetrics:
    collection_interval: 5s
    scrapers:
      cpu:
      memory:
        metrics:
          system.memory.limit:
            enabled: true
      disk:

processors:
  batch:
exporters:
  debug:
    verbosity: detailed
  otlp/jaeger:
    endpoint: localhost:14317
    tls:
      insecure: true
  prometheus:
    endpoint: 0.0.0.0:8889
service:
  pipelines:
    metrics:
      receivers: [otlp, hostmetrics]
      processors: [batch]
      exporters: [debug]

Log output

…/receiver/hostmetricsreceiver main  ❯ make generate
cd /home/dos/Documents/opentelemetry-collector-contrib/internal/tools && GOOS="" GOARCH="" go build -o /home/dos/Documents/opentelemetry-collector-contrib/.tools/genqlient -trimpath github.com/Khan/genqlient
PATH="/home/dos/Documents/opentelemetry-collector-contrib/.tools:$PATH" go generate ./...
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/cpuscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/cpuscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper'
Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
Error: failed loading /home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper/metadata.yaml: metric "system.disk.io_time": invalid semantic-conventions URL: want https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/*#metric-systemdiskiotime, got "https://github.com/open-telemetry/semantic-conventions/blob/v1.38.0/docs/system/system-metrics.md#metric-systemdiskio_time"
make[1]: *** [../../../../../Makefile.Common:264: mdatagen] Error 1
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/diskscraper'
internal/scraper/diskscraper/doc.go:4: running "make": exit status 2
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/loadscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/loadscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/memoryscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/memoryscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/networkscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/networkscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/nfsscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/pagingscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/pagingscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processesscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processesscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processscraper'
make[1]: Entering directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/systemscraper'
make[1]: Leaving directory '/home/dos/Documents/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/systemscraper'
make: *** [../../Makefile.Common:282: generate] Error 1

Additional context

No response

Tip

_{React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it. Learn more here.}

[github-actions]

Pinging code owners:

• cmd/mdatagen: @dmitryax

See Adding Labels via Comments if you do not have permissions to add labels yourself.