Error during parsing: unrecognized response matcher expression

francislavoie · October 3, 2021, 2:46am

expression cannot be used to match responses. The only ones currently available are status and header, as described in the docs:

Also, you need to define a handle_response block, under which you can define handler directives (like redir).

That said, handle_response currently has a bug that prevents it from working with any requests that have a non-empty response body. So it’s not currently possible to do what you’re trying to do, unfortunately.

github.com/caddyserver/caddy

handle_response errors with "read on closed response body"

opened 02:42AM - 22 Aug 21 UTC

closed 06:00PM - 18 Oct 21 UTC

polarathene

bug

Following the [docs for `reverse_proxy` directive with `handle_response`](https:…//caddyserver.com/docs/caddyfile/directives/reverse_proxy#intercepting-responses) on a very basic JSON response endpoint results in failure, but modifying the header elsewhere in Caddy works as expected. **Caddyfile (v2.4.3):** ```Caddyfile :80 { # Works: #header Cache-Control "max-age=10" reverse_proxy localhost:8000 { handle_response { # Errors: header Cache-Control "max-age=10" } # Works: #header_down Cache-Control "max-age=10" } } ``` **Error logged:** ``` 2021/08/22 02:34:00.645 ERROR http.handlers.reverse_proxy reading from backend {"error": "http: read on closed response body"} 2021/08/22 02:34:00.645 ERROR http.handlers.reverse_proxy aborting with incomplete response {"error": "http: read on closed response body"} ``` The upstream still received the request and responded no differently AFAIK, in the web browser network tools Caddy has sent a response header but omitted the body. --- For added context, intention was to match on `Content-Type application/json` rather than the URI; but AFAIK this is only available via the response, and thus can only be matched within `handle_response`? As the response matcher is not required to reproduce the error I have excluded it.