j'ai pas fait comme ça, je suis parti sur

# ACL
acl my_host              hdr(host) -i hostname
acl my_path            path_beg /path
# Proxy_pass
http-request set-header X-Location-Path %[capture.req.uri]  if my_path my_host
http-request replace-header X-Location-Path ^(\/path/)(.*) \2  if my_path my_host
http-request set-uri https://hostname/%[hdr(X-Location-Path)] if my_path my_host