Inconsistent Behavior of request-capture with hdr() in HAProxy ConfigMap

[odoucet]

When following the documentation and setting the following in the ConfigMap:

    request-capture: |
      hdr(user-agent)
      hdr(referer)

The resulting haproxy.cfg includes lines like:

http-request capture hdr(user-agent) len 256 if { var(txn.path_match) -m dom xxxxxxxx }
http-request capture hdr(referer) len 256 if { var(txn.path_match) -m dom xxxxxxx }

However, the use of hdr() leads to incorrect log entries because it splits header values at commas. This behavior is not well-documented and was previously identified in haproxy/haproxy#796
As a result, the User-Agent log appears truncated or malformed. For example:

x.x.x.x - - [11/Jul/2025:12:30:55 +0000] "POST https://example.com HTTP/2.0" 200 431 "https://referer" "like Gecko) Chrome/138.0.0.0 Mobile Safari/537.36"

This is the same issue described in haproxy/haproxy#794 (comment) where the header gets cut off due to internal comma handling.

To obtain correct log output, I had to replace the above with:

    frontend-config-snippet: |
      capture request header Referer len 128
      capture request header User-Agent len 128

However, this is not supported via the request-capture field, which is currently the documented and suggested approach.

My suggestions

To avoid misleading configurations and broken logs for other users:

• Allow full header capture using request-capture: header user-agent that maps to the correct capture request header directive rather than http-request capture.
• Alternatively, introduce a dedicated ConfigMap field for raw capture request usage.
• In either case, update the documentation to warn users about hdr() behavior with comma-separated headers like User-Agent.

This issue is easy to overlook but significantly impacts observability, and many users are likely to follow the current (broken) example in the documentation.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[odoucet]

bug/improvement still active

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[odoucet]

bug/improvement still active

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[odoucet]

not stale