HA Proxy - remove or add www and redirect

redirect prefix http://example.com code 301 if { hdr(host) -i www.example.com }

Please see the documentation of the redirect prefix rule for more information.

If you are using a newer version of HAProxy, i.e. at least 1.6, you can use a more generic syntax which allows to redirect any host, not just explicitly named

http-request redirect prefix http://%[hdr(host),regsub(^www\.,,i)] code 301 if { hdr_beg(host) -i www. }

Here, we are using the regsub filter to dynamically generate the correct hostname without the www. prefix.

In case you want to perform a redirect the other way around, i.e. to add a www if there is none already, the rule becomes simpler:

http-request redirect prefix http://www.%[hdr(host)] code 301 unless { hdr_beg(host) -i www. }