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Using Haproxy 1.5.12 running on Ubuntu 12.04

My website gets a lot of requests like this one:

http://www.example.com/foo/bar/mypage.php?gallery=&position=3

the correct URL should be:

http://www.example.com/foo/bar/mypage.php?gallery=photogallery&position=3

I've been successful in rewriting requests to the correct URL, but I would also like to issue a 301 redirect to clients.

Following this post: redirect rewritten url using haproxy I tried:

acl fix_gallery url_sub gallery=&
reqrep (.*)gallery=&(.*) \1gallery=photogallery&\2
redirect prefix / code 301 if fix_gallery

Trying to be creative I've tried:

acl fix_gallery url_reg (.*)gallery=&(.*)
acl fix_gallery urlp_reg(gallery) -m str ""
acl fix_gallery urlp_reg(gallery) -m len 0

and many more. But nothing seems to work, so I'm obviously missing something.

Any suggestions?

Thanks

Community
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jeremyjr
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  • The problem is that the `reqrep` causes the `fix_gallery` ACL to evaluate as false when it's evaluated for the `redirect`, because the request buffer has been edited by the `reqrep` such that the pattern is no longer found. The conditions in an ACL are evaluated each time the ACL is tested, rather than what you might intuitively expect. That's why the "dummy header" is used in the answer, below -- to stash the value without changing the ACL. Newer versions also support named variables scoped to request, response, transaction, or session, which can be used for similar purposes. – Michael - sqlbot Mar 31 '16 at 02:55
  • Michael thanks for the explanation. acl are rather counterintuitive in this way. – jeremyjr Mar 31 '16 at 10:46

1 Answers1

2

You can achieve what you're looking for using 3 lines of config that leverage the http-request keyword.

The first sets a dummy header that we'll use in the following two.

http-request set-header X-Location-Path %[capture.req.uri] if fix_gallery

The second performs the substitution you need to fix the URL query.

http-request replace-header X-Location-Path (.*)gallery=&(.*) \1gallery=photogallery&\2 if fix_gallery

The final line does the direction to the changed URL.

http-request redirect location http://www.example.com/%[hdr(X-Location-Path)] if fix_gallery

This works if you only have one domain, but it's possible to build http-request redirect lines that will work with any domain and scheme.

http-request redirect location https://%[hdr(host)]/%[hdr(X-Location-Path)] if fix_gallery { ssl_fc }
http-request redirect location http://%[hdr(host)]/%[hdr(X-Location-Path)] if fix_gallery !{ ssl_fc }
GregL
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