Make overriding scope.name with logrecord.target configurable in OTLP Log Exporter

[lalitb]

Fixes open-telemetry/opentelemetry-specification#1890
Design discussion issue (if applicable) #

Changes

• Added feature flag populate-instrumentation-scope-from-target in Cargo.toml for opentelemetry-otlp and opentelemetry-proto.
• The flag is enabled by default for both.
• If flag is enabled scope.name is populated with LogRecord.target. scope.version and other fields are empty.
• If flag is disabled, scope is populated from opentelemetry-sdk's "InstrumentatonLibrary".

output for:

    info!(name: "my-event", target: "my-target", "hello from {}. My price is {}", "apple", 1.99);

feature flag disabled

2024-09-11T09:33:21.399Z        info    LogsExporter    {"kind": "exporter", "data_type": "logs", "name": "debug", "resource logs": 1, "log records": 1}
2024-09-11T09:33:21.399Z        info    ResourceLog #0
Resource SchemaURL:
Resource attributes:
     -> service.name: Str(basic-otlp-example)
ScopeLogs #0
ScopeLogs SchemaURL:
InstrumentationScope opentelemetry-appender-tracing 0.25.0
LogRecord #0
ObservedTimestamp: 2024-09-11 09:33:21.3943082 +0000 UTC
Timestamp: 1970-01-01 00:00:00 +0000 UTC
SeverityText: INFO
SeverityNumber: Info(9)
Body: Str(hello from apple. My price is 1.99)
Trace ID:
Span ID:
Flags: 0
        {"kind": "exporter", "data_type": "logs", "name": "debug"}

feature flag enabled

2024-09-11T09:33:51.736Z        info    LogsExporter    {"kind": "exporter", "data_type": "logs", "name": "debug", "resource logs": 1, "log records": 1}
2024-09-11T09:33:51.737Z        info    ResourceLog #0
Resource SchemaURL:
Resource attributes:
     -> service.name: Str(basic-otlp-example)
ScopeLogs #0
ScopeLogs SchemaURL:
InstrumentationScope my-target
LogRecord #0
ObservedTimestamp: 2024-09-11 09:33:51.7344587 +0000 UTC
Timestamp: 1970-01-01 00:00:00 +0000 UTC
SeverityText: INFO
SeverityNumber: Info(9)
Body: Str(hello from apple. My price is 1.99)
Trace ID:
Span ID:
Flags: 0
        {"kind": "exporter", "data_type": "logs", "name": "debug"}

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 58.33333% with 5 lines in your changes missing coverage. Please review.

Project coverage is 77.9%. Comparing base (e206533) to head (48463eb).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-proto/src/transform/logs.rs	58.3%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   open-telemetry/opentelemetry-specification#2102     +/-   ##
=======================================
- Coverage   78.0%   77.9%   -0.1%     
=======================================
  Files        121     121             
  Lines      20939   20944      +5     
=======================================
+ Hits       16335   16336      +1     
- Misses      4604    4608      +4     

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[cijothomas]

https://github.com/open-telemetry/opentelemetry-specification/issues/4154
I am wondering if we should offer this feature flag at all, given the target should be populated as scope always. The appender-name and version can be attributes on the scope. Need to follow the above spec issue before closely.

[lalitb]

Interesting. We can instead have a feature flag to populate the appender-name/version as attributes, and keep target as scope as we do currently.

[cijothomas]

I think that could work, we need to wait for the spec issue to get resolved. For now, we can continue to keep target as scope. what do you think?

[lalitb]

Sure, we can close this PR and make a decision once the spec issue is resolved