Willy,
Am 15.05.19 um 11:31 schrieb Tim Düsterhus:
>>> 2. 'req*' and 'rsp*'. I remember that they allow some modification that
>>> cannot easily be replicated otherwise (but I'll have to check that
>>> first).
>>
>> Sure but practically speaking such modifications do not make sense in
>> the real world (e.g. rename many header names at once). And the "excuse"
>
> I believe it was some kind of request path rewriting that was not easily
> possibly with `http-request set-path` (maybe because of syntax
> limitations). I'll definitely check and report back.
>
Okay, I looked it up. It's simple: Everything that needs capturing
groups for the path modifications is not exactly trivial or clean to
replicate otherwise (but it's possible as I found out by scrolling
through the docs and seeing http-request replace-header):
Consider I have URLs in a folder that I want to map to “git object
directory style” hashed folders (that's a hypothetical example, but I've
used something similar in production):
/foo/1234.png will become /12/34
This is my config:
> defaults
> timeout server 1s
> mode http
> option httpclose
>
> listen fe
> bind :8080
> reqrep ^([^\ :]*)\ /foo/(.{2})(.*).png \1\ /\2/\3
> http-request set-header FE 1
>
> server example localhost:8082
>
> listen fe2
> bind :8081
> http-request set-header XXX %[path]
> http-request replace-header XXX /foo/(.{2})(.*).png /\1/\2
> http-request set-path %[req.hdr(XXX)]
> http-request del-header XXX
> http-request set-header FE 2
>
> server example localhost:8082
Both frontends will do the correct replacement, but IMO the reqrep one
is more readable (not that any of these are really readable):
> [timwolla@~]begin
> nc -l 127.0.0.1 8082 &
> curl -q localhost:8080/foo/1234.png
> wait
> echo ============
> nc -l 127.0.0.1 8082 &
> curl -q localhost:8081/foo/1234.png
> wait
> end
> GET /12/34 HTTP/1.1
> host: localhost:8080
> user-agent: curl/7.47.0
> accept: */*
> fe: 1
>
> <html><body><h1>504 Gateway Time-out</h1>
> The server didn't respond in time.
> </body></html>
> ============
> GET /12/34 HTTP/1.1
> host: localhost:8081
> user-agent: curl/7.47.0
> accept: */*
> fe: 2
> Connection: close
>
> <html><body><h1>504 Gateway Time-out</h1>
> The server didn't respond in time.
> </body></html>
The obvious `http-request set-path %[path,regsub(...)]` as suggested in
the docs for `http-request set-query` does *NOT* work, because the
`regsub` parameters cannot contain the closing parenthesis required for
capture groups.
Best regards
Tim Düsterhus
