HAProxy reqrep not replacing string in url - haproxy

Question

We have deprecated some software which was available under http://localhost/test and is now available under http://localhost/app/testing. We are using HAProxy 1.4
Thus, I want via haproxy, to replace all urls containing /test with /app/testing/. I tried first with a redirect prefix in order to keep the query string, but /test wasn't removed from the url and had something like /app/testing/test/?id=x.
frontend all
bind 0.0.0.0:80
timeout client 86400000
acl is_test path_beg /test
redirect prefix /app/testing code 301 if is_test
Then used a reqrep, which seems to redirect to the new software, but the /test string in the url is never replaced.
frontend all
bind 0.0.0.0:80
timeout client 86400000
reqrep ^([^\ :]*)\ /test[/]?(.*) \1\ /app/testing/\2

Answer 1

Since url rewriting isn't possible with version 1.4 and we didn't want to update HAProxy, we went on using reqrep and keeping the old link as is with
reqrep ^([^\ :]*)\ /test[/]?(.*) \1\ /app/testing/\2

Answer 2

Try this
This works for me with your scenario on HAProxy 1.6
acl test path_beg -i /test
http-request set-header X-Location-Path %[capture.req.uri] if test
http-request replace-header X-Location-Path /test /app/testing if test
http-request redirect location %[hdr(X-Location-Path)] if test
use_backend WHEREVER if test

Answer 3

Using redirect prefix is meant, going by the HAProxy examples, more for changing the hostname, but keeping the path. For example, http://apple.com/my/path could be redirected to http://orange.com/my/path with:
redirect prefix http://orange.com if apple
The HAProxy 1.4 docs say:
With "redirect prefix", the "Location" header is built from the
concatenation of < pfx > and the complete URI path
To me, that suggests that you would expect whatever you put for the "prefix" will be prefixed to what was already in the path. That explains the behavior you were seeing. This is useful for changing to a new domain (e.g. from apple.com to orange.com), but keeping the original path (e.g. /my/path).
You can switch to using redirect location to replace the entire URL. The following would redirect http://apple.com/my/path to http://orange.com/path:
redirect location http://orange.com/path if apple
UPDATE:
In the case where you want to change the URL, but keep the query string, use reqirep or reqrep to rewrite the URL, as you are doing, but also put a redirect prefix into the frontend. The URL will be rewritten and then the user will be redirected to it so they see it.
You might be able to set the "prefix" to "/". The HAProxy docs say:
As a special case, if < pfx > equals exactly "/", then nothing is
inserted before the original URI. It allows one to redirect to the
same URL (for instance, to insert a cookie).
Using your code example, something like this:
reqrep ^([^\ :]*)\ /test[/]?(.*) \1\ /app/testing/\2
redirect prefix / code 301 if is_test