Haproxy path manipulation - url

Question

In Google Cloud Platform we do have a haproxy which serves as proxy for our internal VPN and do URL redirects from GCP DNS to proxy.mycompany.com (our haproxy) where we do further manipulation.
Haproxy is from image 2.0.8-alpine
Nginx is based on image 1-alpine
Lately I have installed nginx which serves static files.
Nginx is setup for autoindex on, accesible on url static-files.mycompany.com, and configured to show root of a gcs-bucket. Therefore if you visit static-files.mycompany.com you will see content of gcs-bucket:
directory static-files
any file in a bucket.
static-files directory contains static website files which were generated by hugo.
Those files contain paths like /docu/file.md
I've managed to configure haproxy that it will forward any requests for url website.mycompany.com to static-files.mycompany.com/static-files and show the generated static website by configuring this in backend section of haproxy config:
acl p_root path -i /
http-request set-path /static-files/\1 if p_root
Every time I visit website.mycompany.com the path is redirected to website.mycompany.com/static-files (which is actually static-files.mycompany.com/static-files )
However, the site is broken:
css is not loading, file is located in / and the requests aims for website.mycompany.com/mycss.file, but the file can be found under website.mycompany.com/static-files/mycss.file due to path manipulation above
Every link on site dead, requests website.mycompany.com/my-link-to-file but file is under
website.mycompany.com/static-files/my-link-to-file
I have a limited possibility to configure haproxy, most probably I can add parameters to existing backend and frontend section, here I am providing parameters I cannot change:
global
log stdout format raw local0 info
maxconn 30000
tune.ssl.default-dh-param 2048
resolvers vpc
parse-resolv-conf
hold valid 120s
defaults
mode http
log global
option dontlognull
#option tcplog
option httplog
option forwardfor
option redispatch
maxconn 3000
retries 3
timeout connect 5s
timeout client 50s
timeout server 50s
timeout tunnel 1h
timeout client-fin 30s
timeout http-keep-alive 4s
balance roundrobin
default-server check resolvers vpc
default-server on-marked-down shutdown-sessions
default-server max-reuse 100
frontend http
bind *:80
redirect scheme https code 302 if !{ ssl_fc }
monitor-uri /_healtz
use_backend %[hdr(host),lower]
frontend https
bind *:443 ssl no-sslv3 crt /config/haproxy_certificate.pem alpn http/1.1,h2
http-response add-header Via 1.1\ %[env(HOSTNAME)]
http-request add-header Via 1.1\ %[env(HOSTNAME)]
http-request add-header X-Forwarded-Proto https
http-request capture req.hdr(Host) len 40
http-request capture req.hdr(User-Agent) len 120
use_backend %[hdr(host),lower]
backend proxy.mycompany.com
stats enable
stats uri /
I would like to achieve the following:
By visiting website.mycompany.com I will be forwarded to static-files.mycompany.com/static-files in the background, however the URL will remain as website.mycompany.com and therefore the generated static website paths remain working and so the static site. Or Am I mistaken ?
I am open to any reasonable suggestion.
thank you

Answer 1

Well, it was quite simple in the end
http-request replace-uri ([^/:]*://[^/]*)?(.*) \1/static-files\2
Did the trick.
edit:
to avoid and infinite loop of /static-files/static-files/
acl remove_static-files path_beg -i /architecture-diagrams
http-request replace-uri ([^/:]*://[^/]*)?(.*) \1/static-files\2 if !remove_static-files