Unable to replace all instances of a given string in request header

[jvanheesch]

Reproducer can be found here.

I am unable to replace all instances of a given string input with replacement value output.
I checked the source code, but could not come up with a different config that would achieve the desired result.
As a workaround, we currently resort to adding multiple instances of the exact same RewriteValueRule.

[tomMoulard]

Hello @jvanheesch,

Thanks for your interest in this Traefik Plugin !

What do you mean when you say:

I am unable to replace all instances of a given string input with replacement value output.

By all instances, do you mean that you have multiple headers where you want to replace the value.

like

Replace:

$ > curl -I https://example.com
HTTP/2 200 
accept-ranges: bytes
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
content-type: text/html
date: Mon, 03 Jun 2024 15:31:59 GMT
etag: "5fd8e6de-690f"
X-Forwarded-For: 10.0.0.0
X-Real-IP: 10.0.0.0

To:

$ > curl -I https://google.com
HTTP/2 200 
accept-ranges: bytes
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
content-type: text/html
date: Mon, 03 Jun 2024 15:31:59 GMT
etag: "5fd8e6de-690f"
X-Forwarded-For: 11.0.0.0
X-Real-IP: 11.0.0.0

This is possible by using a plugin configuration that could look like this:

- Rule:
      Name: 'Header rewriteValue'
      Header: 'X-(Real-IP|Forwarded-For)'
      Value: '10.(.*)'
      ValueReplace: '11.$1'
      Type: 'RewriteValueRule'

Or do you mean that you have multiple instance of the value in a single header value ?

like

Replace:

$ > curl -I https://example.com
HTTP/2 200 
accept-ranges: bytes
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
content-type: text/html
date: Mon, 03 Jun 2024 15:31:59 GMT
etag: "5fd8e6de-690f"
X-Forwarded-For: 10.0.0.0

To:

$ > curl -I https://google.com
HTTP/2 200 
accept-ranges: bytes
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
content-type: text/html
date: Mon, 03 Jun 2024 15:31:59 GMT
etag: "5fd8e6de-690f"
X-Forwarded-For: 10.42.42.42

[jvanheesch]

@tomMoulard Thank you for the quick response!

I am trying the second, i.e. replacing multiple (all) instances of a string in a single header value.
I've created a reproducer, which can be found here, to share my config + actual/expected behavior.
Please let me know if you have any further questions!

[tomMoulard]

Indeed the could be a good fix to add to the RewriteValueRule handler!