Hi Tim,
On Wed, May 15, 2019 at 05:09:31PM +0200, Tim Düsterhus wrote:
> 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):
I'm having a different view on this. The one using the headers hack is
horrible while the reqrep one is simply ugly :-)
Really, this is a good reason for having a "replace-uri" action. It should
mostly be a copy-paste of the replace-header code but applied to the URI,
and will be much simpler and safer to use than any of the tricks above.
You'd then do :
http-request replace-uri /foo/(.{2})(.*).png /\1/\2
instead of :
reqrep ^([^\ :]*)\ /foo/(.{2})(.*).png \1\ /\2/\3
And more importantly it will respect the execution order related to other
HTTP rules!
> 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.
Yep I see. I've added feature request #100 to keep track of this. I'm
willing to merge this even late into 2.0 and to make sure we can warn
on rsp/req*. Just let me know if you're interested. Also feel free to
add replace-path to replace only the path component as I suspect it could
be useful as well.
Oh BTW I've merged your 6 patches into the "next" branch and merged two
of them into master.
thanks,
Willy
