Fix OTLPMetricExporter ignores preferred_aggregation property

[Dudssource]

Description

OTLPMetricExporter was ignoring the preferred_aggregation property, not allowing any kind of customization directly on the constructor.

Fixes #3522

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Testing informing a custom aggregation (like informing an ExplicitBucketHistogramAggregation)

I've tried the following configuration for my MetricReader:

# OTLP metrics
reader = PeriodicExportingMetricReader(
    OTLPMetricExporter(
        endpoint="http://localhost:4318/v1/metrics",
        session=session,
        compression=Compression.Gzip,
        timeout=5,
        preferred_aggregation={
            Histogram: ExplicitBucketHistogramAggregation(
                boundaries=[0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 10, 20, 30, 40, 50, 60, 300, 600],
            )
        },
    )
)

On my OTLP collector (localhost:4318), I configured the logging exporter for metrics:

receivers:
  otlp:
    protocols:
      http:
        endpoint: 0.0.0.0:4318

exporters:
  logging:
    verbosity: detailed

service:
  telemetry:
    logs:
      level: DEBUG
  pipelines:
    metrics:
      receivers: [otlp]
      processors: []
      exporters: [logging]

After this setup, I was able to see my histograms being exported with my explicit configured boundaries.

Before (without the fix):

otel-collector_1  | Count: 1
otel-collector_1  | Sum: 0.808466
otel-collector_1  | Min: 0.808466
otel-collector_1  | Max: 0.808466
otel-collector_1  | ExplicitBounds #0: 0.000000
otel-collector_1  | ExplicitBounds #1: 5.000000
otel-collector_1  | ExplicitBounds #2: 10.000000
otel-collector_1  | ExplicitBounds #3: 25.000000
otel-collector_1  | ExplicitBounds #4: 50.000000
otel-collector_1  | ExplicitBounds #5: 75.000000
otel-collector_1  | ExplicitBounds #6: 100.000000
otel-collector_1  | ExplicitBounds #7: 250.000000
otel-collector_1  | ExplicitBounds #8: 500.000000
otel-collector_1  | ExplicitBounds #9: 750.000000
otel-collector_1  | ExplicitBounds #10: 1000.000000
otel-collector_1  | ExplicitBounds #11: 2500.000000
otel-collector_1  | ExplicitBounds #12: 5000.000000
otel-collector_1  | ExplicitBounds #13: 7500.000000
otel-collector_1  | ExplicitBounds #14: 10000.000000

After (with the fix):

otel-collector_1  | ExplicitBounds #0: 0.050000
otel-collector_1  | ExplicitBounds #1: 0.100000
otel-collector_1  | ExplicitBounds #2: 0.500000
otel-collector_1  | ExplicitBounds #3: 1.000000
otel-collector_1  | ExplicitBounds #4: 1.500000
otel-collector_1  | ExplicitBounds #5: 2.000000
otel-collector_1  | ExplicitBounds #6: 2.500000
otel-collector_1  | ExplicitBounds #7: 3.000000
otel-collector_1  | ExplicitBounds #8: 4.000000
otel-collector_1  | ExplicitBounds #9: 5.000000
otel-collector_1  | ExplicitBounds #10: 10.000000
otel-collector_1  | ExplicitBounds #11: 20.000000
otel-collector_1  | ExplicitBounds #12: 30.000000
otel-collector_1  | ExplicitBounds #13: 40.000000
otel-collector_1  | ExplicitBounds #14: 50.000000
otel-collector_1  | ExplicitBounds #15: 60.000000
otel-collector_1  | ExplicitBounds #16: 300.000000
otel-collector_1  | ExplicitBounds #17: 600.000000

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Dudssource (704b4d8, 1718871, cdded4a, be1cfc1, 14af46f, 718ea2d, c59c7c9, 057273e, 77fde48, 491482d, 489b4c5, 6b5cf7a, 4f805cc, a6343f6, f8b03e3, b5c95cc, 77869df, cb825d9)
• ✅ login: ocelotl / name: Diego Hurtado (479e28e, ce20dd0)

[srikanthccv]

Let's add a unit test and CHANGELOG entry

[Dudssource]

Let's add a unit test and CHANGELOG entry

Thanks @srikanthccv for your feedback!
I just added a changelog entry and a unit test, pls let me know if I need to add something else.

new changes after review

[Dudssource]

Linter is now passing (0195013)

[Dudssource]

Pylint linter fixed on d60819a