request-transformer rename is not preserving renamed header casing

[l8nite]

Is there an existing issue for this?

• I have searched the existing issues

Kong version ($ kong version)

3.4.0

Current Behavior

Consider request-transformer configuration:

plugins:
- name: request-transformer
  service: foo
  config:
    rename:
      headers:
      - X-FOO-QixQux:X-BAR-QixQux

When renaming the header, the new value sent upstream is X-Bar-Qixqux

Expected Behavior

The expected header sent upstream is X-BAR-QixQux (case sensitive).

Now, according to HTTP RFC, the plugin behavior is OK; however, we have run into some implementation of upstream services that require strict http header casing, and it would be better if Kong preserved the renamed header casing.

This is similar to Issue #4504

Steps To Reproduce

Set up request-transformer plugin with the above config, execute request with inbound header that is renamed, observe the casing of the header sent to upstream.

Anything else?

No response

[StarlightIbuki]

Thanks for reporting this. This might be a breaking change to make it case-sensitive but it looks alright: people who care about the case will write it correctly in the configuration. We will be discussing this.

[hanshuebner]

Created internal ticket KAG-2599

[github-actions]

This issue is marked as stale because it has been open for 14 days with no activity.

[zyiqian]

Hi @hanshuebner ,Has this issue been resolved? I seem to be encountering the same problem. When I rename the header, it doesn't seem to work. But the interesting thing is that when I add a new header it works。
My kong version is 3.1.1。

Plugin configuration:
apiVersion: configuration.konghq.com/v1 kind: KongPlugin metadata: name: request-transformer-remoteip plugin: request-transformer config: rename: headers: - RemoteIp:remoteip - X-Real-Ip:remoteip - X-Forwarded-For:remoteip add: headers: - X-Custom-Header:CustomValue

log:

message: header params name:X-Custom-Header,value:CustomValue
message: header params name:X-Forwarded-For,value:xxxxx

Looking forward to your reply, thank you.

[hanshuebner]

Hi @zyiqian, I've followed up internally to see whether we can get this fixed.

[StarlightIbuki]

#12244

[dndx]

We do not plan on addressing this issue due to widespread downstream impact, however, you should be able to use kong.service.request.set_headers and https://docs.konghq.com/hub/kong-inc/post-function/ to achieve the same goal.