fix(exporter-logs-otlp-proto): programatic headers take precedence ov…

[Vunovati]

…er environment variables

Which problem is this PR solving?

Exporters are not respecting the documented behaviour (link) when it comes to headers.

Settings configured programmatically take precedence over environment variables. Per-signal environment variables take precedence over non-per-signal environment variables.

Continuation of the previous PR #4334 based on the discussion
#4334 (review)

Fixes #2370

Short description of the changes

override OTEL_EXPORTER_OTLP_METRICS_HEADERS and OTEL_EXPORTER_OTLP_HEADERS with config.headers supplied to OTLPLogExporter and OTLPTraceExporter

Applied to:

• @opentelemetry/exporter-logs-otlp-proto
• @opentelemetry/exporter-logs-otlp-http
• @opentelemetry/exporter-trace-otlp-proto
• @opentelemetry/exporter-trace-otlp-http

Did not change anything in grpc exporters for traces and logs as setting headers for that protocol probably does not make sense:

opentelemetry-js/experimental/packages/otlp-grpc-exporter-base/src/OTLPGRPCExporterNodeBase.ts

Line 52 in 5b0fb7b

diag.warn('Headers cannot be set when using grpc');

Type of change

Please delete options that are not relevant.

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Added additional tests testing that the programmatic settings take precedence.

1. for headers
2. for url, which was already working per spec but was not covered with unit tests

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added

[codecov]

Codecov Report

Merging #4351 (7bbf861) into main (0206181) will decrease coverage by 0.02%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

❗ Current head 7bbf861 differs from pull request most recent head b02f746. Consider uploading reports for the commit b02f746 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4351      +/-   ##
==========================================
- Coverage   92.24%   92.22%   -0.02%     
==========================================
  Files         333      333              
  Lines        9459     9459              
  Branches     2009     2009              
==========================================
- Hits         8725     8724       -1     
- Misses        734      735       +1     

Files	Coverage Δ
...ogs-otlp-http/src/platform/node/OTLPLogExporter.ts	100.00% <100.00%> (ø)
...gs-otlp-proto/src/platform/node/OTLPLogExporter.ts	100.00% <ø> (ø)
...e-otlp-http/src/platform/node/OTLPTraceExporter.ts	100.00% <ø> (ø)
...-otlp-proto/src/platform/node/OTLPTraceExporter.ts	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

[pichlermarc]

Looks good, thanks for taking care of this. 🙂