feat(opentelemetry): Allow header_type to be set

[nbialostosky]

Summary

At the moment the opentelemtry plugin sets the default_header_type for propigations:

https://github.com/Kong/kong/blob/master/kong/plugins/opentelemetry/handler.lua#L150

However, doesn't allow the modification of header_type in the schema, so it always defaults to preserve. However, based on the function it's calling:

https://github.com/Kong/kong/blob/master/kong/tracing/propagation.lua#L432

-- If conf_header_type is set to preserve, found_header_type is used over default_header_type;

The above means the default_header_type is never used. We want the default_header_type to be used, and we want to ignore the incoming header type.

I am not implmenting the ability to modify the default_header_type as opentelemetry notes it should default to w3c which it currently is:

https://opentelemetry.io/docs/concepts/signals/traces/#context-propagation

Checklist

• The Pull Request has tests
• [N/A] There's an entry in the CHANGELOG note, it specifically says not to edit this: https://github.com/Kong/kong/blob/master/CONTRIBUTING.md#submitting-a-patch
• [?] Can submit documentation if needed

Full changelog

• Implement the ability to set header_type for the opentelemetry plugin

Issue reference

Fix #10246

[nbialostosky]

Note: I couldn't get the tests to run locally with make test or with gojira:

gojira up
gojira run make dev
gojira run busted spec/03-plugins/37-opentelemetry

When I attempted the gojira command, it was returning a bazel error. I was hoping that CI would take care of running the test to confirm this functionality once I raised the PR.

[samugi]

looks great! Just some small observations:

[samugi]

I couldn't get the tests to run locally

It is possible that you'll have to run gojira run make dev-legacy, there may be some temporary issues with the Bazel build that we are working on.

There's an entry in the CHANGELOG note, it specifically says not to edit this

ah! Thanks for pointing that out, we will fix that, please do feel free to update the CHANGELOG

[?] Can submit documentation if needed

that would be awesome! ❤️ the docs for this plugin can be found on this page.

[nbialostosky]

FWIW I still couldn't get this working locally with gojira run make dev-legacy, I was getting:

─$ gojira run busted spec/03-plugins/37-opentelemetry
✱✱✱✱✱
0 successes / 0 failures / 5 errors / 0 pending : 0.223766 seconds

Error → ./kong/tools/utils.lua @ 37
suite spec/03-plugins/37-opentelemetry/01-otlp_spec.lua
./kong/tools/utils.lua:37: attempt to index global 'ngx' (a nil value)

ah! Thanks for pointing that out, we will fix that, please do feel free to update the CHANGELOG

Thanks! Went ahead and added a note in the CHANGELOG with the recent commit.

that would be awesome!

Working on the docs now, will post a link here once that's done!

[nbialostosky]

Added documentation here: Kong/docs.konghq.com#5422

Wasn't sure what to point at, so pointed to main, since not sure when this PR will get approved/merged/released.

[samugi]

FWIW I still couldn't get this working locally with gojira run make dev-legacy, I was getting:

─$ gojira run busted spec/03-plugins/37-opentelemetry
✱✱✱✱✱
0 successes / 0 failures / 5 errors / 0 pending : 0.223766 seconds

Error → ./kong/tools/utils.lua @ 37
suite spec/03-plugins/37-opentelemetry/01-otlp_spec.lua
./kong/tools/utils.lua:37: attempt to index global 'ngx' (a nil value)

ah! Thanks for pointing that out, we will fix that, please do feel free to update the CHANGELOG

Thanks! Went ahead and added a note in the CHANGELOG with the recent commit.

that would be awesome!

Working on the docs now, will post a link here once that's done!

@nbialostosky alright that makes sense, please use gojira run bin/busted spec/03-plugins/37-opentelemetry instead.
This is just an FYI, I'm approving the CI runs now.

[nbialostosky]

New PR link for the docs pointed at the proper release branch: Kong/docs.konghq.com#5431

[nbialostosky]

This is just an FYI, I'm approving the CI runs now.

Thanks! To close the loop, the command you provided worked and I was able to successfully run the tests locally, they passed. I will share this information with my team so we are all able to test locally before raising upstream PR's.

[samugi]

looks great @nbialostosky! This just needs a rebase to resolve a couple of conflicts and then it'll be ready to merge. Thanks!

[nbialostosky]

@samugi Thanks! Went ahead and rebased and resolved the conflicts, lemme know if you need anything else from my end!