* reverseproxy: Only retry responses for expressions that use response data
Since #7569 every lb_retry_match set with an expression is evaluated against
upstream responses. An expression that only tests the request, such as
{http.request.method} == "POST", then matched every successful response:
the request was sent again to the next upstreams and the client got a 502
once retries ran out. Only treat expressions referencing {rp.*} placeholders
as response conditions.
* reverseproxy: Only count placeholders set from the response as response data
* reverseproxy: Read response placeholders from the checked expression
The expression matcher records the placeholder names its checked CEL
expression reads, so retry_match finds direct ph() calls and ignores
escaped placeholder text in string literals. A placeholder name only
known at evaluation time counts as response data.
* reverseproxy: Match response placeholder names exactly
Only the header placeholders are matched by prefix now, and both
upstream latency placeholders are listed. MatchExpression.Placeholders
returns a copy, so callers cannot change the provisioned matcher.
(cherry picked from commit 7c7456353e)
970dc7cf00