On Thu, Dec 4, 2014 at 12:09 AM, Ryan <rnidef...@gmail.com> wrote:
> When I received URL's with the following format:
>
> /1/a/b/c
>
> I rewrite the URL removing the digit like so:
>
> /v2.0.0/a/b/c
>
> And I need to set a header with the value of the digit I replaced, i.e.:
>
> X-ID: 1
>
> Is it possible to do this within haproxy? I am able to reqrep the original
> url, and set an ACL to be used with an "http-request add-header" directive,
> but I dont know how to extract the url value and either save it for use in
> the add-header, or to write a format string in the add-header directive that
> will do this.
>
> I'm playing around with something like this but not having much luck:
>
> acl url_id path_reg ^/([0-9]+)/.*$
> http-request add-header X_ID %[path_reg(^/([0-9]+)/.*$)] if url_id
>
> Any ideas?
>
> Thanks,
> Ryan



Hi Rian,

Either there is a bug in the code or the documentation is inacurate,
in chapter 7.3.6 HTTP samples.
The document says we can fetch content using a sample called path and
all its derivatives, including path_reg.

Actually, when I add the following in my conf:
  http-request set-header X-blah %[path_reg .*]
I have a configuration parsing error because of the slash.
When I backslash it:
 http-request set-header X-blah %[path_reg\ .*]
The configuration is valid (from a syntax point of view) but HAProxy
doesn't do anything.


So in your case, I would do this for now:
 acl url_id path_reg ^/([0-9]+)/.*$
 http-request set-header X_ID %[path] if url_id
 http-request replace-value X_ID ^/([0-9]+)/.*$ \1 if { req.hdr(X_ID) -m found }

should do the trick.

Baptiste

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