How to stop HAProxy converting my POST to GET-CodePudding

For some reason, haproxy is converting my request. Below is the log output.

wc_haproxy    | 172.29.0.1:35296 [03/Nov/2021:22:03:44.901] http http/<NOSRV> 0/-1/-1/-1/0 302 134 - - LR-- 1/1/0/0/0 0/0 "POST /register HTTP/1.1"
wc_haproxy    | 172.29.0.1:58040 [03/Nov/2021:22:03:44.906] http~ app/app1 0/0/1/0/1 404 130 - - ---- 1/1/0/0/0 0/0 "GET /register HTTP/1.1"

Below is my configuration:

global
  log stdout format raw local0

defaults
    mode http
    timeout client 10s
    timeout connect 5s
    timeout server 10s
    timeout http-request 10s
    log global

frontend http
    bind *:80
    bind *:443 ssl crt /usr/local/etc/haproxy/company.com.pem
    redirect scheme https if !{ ssl_fc }
    option httplog
    acl sub1 hdr_sub(host) -i app.company.com
    use_backend app if sub1
    use_backend frontstore

backend frontstore
    option forwardfor
    option httpchk GET /
    http-check send ver HTTP/1.1 hdr Host frontstore
    server frontstore1 frontstore:8001 check
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }

backend app
    option forwardfor
    option httpchk GET /check
    http-check send ver HTTP/1.1 hdr Host app
    server app1 app:8002 check
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }

Does anyone know why it would do that?

Fyi I'm using the docker image "haproxy:lts-alpine" if that makes any difference.

CodePudding user response：

Because of your frontend configuration:

frontend http
    ...
    redirect scheme https if !{ ssl_fc }

HAProxy is redirecting your application traffic from HTTP to HTTPS. You can check it in your logs, as it is returning a 302 HTTP status code:

wc_haproxy    | 172.29.0.1:35296 [03/Nov/2021:22:03:44.901] http http/<NOSRV> 0/-1/-1/-1/0 302 134 - - LR-- 1/1/0/0/0 0/0 "POST /register HTTP/1.1"

Please, consider review the HAProxy relevant documentation.

The POST 302 redirect to GET conversion is a common browser pattern. Please, consider read this SO question. I think it can be related to your problem.