Limit prometheus exemplar labels

[harshitrjpt]

Changes done:

1. create exemplar's labels object before creating the exemplar object. (deduplicated some code there)
2. calculate labels length or runes.
3. compare label runes with the hardcoded max rune. If limit reached, then return null exemplar obj.
4. Added tests with sample LongSum metric data consisting exemplar for scenarios
   a) exemplar labels below max rune
   b) exemplar labels above max rune

> Task :exporters:prometheus:test

Otel2PrometheusConverterTest > exemplarLabelsAboveLimit() STANDARD_ERROR
    [Test worker] WARN io.opentelemetry.exporter.prometheus.Otel2PrometheusConverter - exemplar labels have 193 unicode code points, exceeding the limit of 128

[codecov]

Codecov Report

Attention: Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.39%. Comparing base (537f5c4) to head (55a1bac).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
.../exporter/prometheus/Otel2PrometheusConverter.java	93.33%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6791      +/-   ##
============================================
+ Coverage     90.11%   90.39%   +0.27%     
- Complexity     6545     6580      +35     
============================================
  Files           728      731       +3     
  Lines         19702    19723      +21     
  Branches       1935     1928       -7     
============================================
+ Hits          17755    17829      +74     
+ Misses         1347     1297      -50     
+ Partials        600      597       -3     

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[harshitrjpt]

Any clue why in 'markdown-link-check' job following links are failing:

  [✖] https://maven-badges.herokuapp.com/maven-central/io.opentelemetry/opentelemetry-api → Status: 503
  [✖] https://maven-badges.herokuapp.com/maven-central/io.opentelemetry/opentelemetry-api/badge.svg → Status: 503

How can we fix this?

[laurit]

Any clue why in 'markdown-link-check' job following links are failing:

  [✖] https://maven-badges.herokuapp.com/maven-central/io.opentelemetry/opentelemetry-api → Status: 503
  [✖] https://maven-badges.herokuapp.com/maven-central/io.opentelemetry/opentelemetry-api/badge.svg → Status: 503

How can we fix this?

Seems to be fixed now.

[laurit]

i'd replace codePoints with unicode code points to make it easier to understand what this warning means

[harshitrjpt]

@laurit addressed.

Task :exporters:prometheus:test

Otel2PrometheusConverterTest > exemplarLabelsAboveLimit() STANDARD_ERROR
    [Test worker] WARN io.opentelemetry.exporter.prometheus.Otel2PrometheusConverter - exemplar labels have 193 unicode code points, exceeding the limit of 128

[jkwatson]

Is this based on the specification somewhere?

[jkwatson]

Can you add a test that covers this (codecov claims it's not tested, and it seems like it would be good to have it covered)