Problem with Location header - http to http rewrite

[wih11 (Peter)]

1. The problem I’m having:

I have a simple reverse proxy to the app that is stubborn enough to ignore all proxy-related requests so it generates redirects with “http://…” in the Location header. I can’t do anything obout it so I’m trying to replace http with https in the response header through Caddy.

header (Caddyfile directive) — Caddy Documentation docs says that it is possible to replace http with https with simple directive:

Replace http:// with https:// in any Location header:
header Location http:// https://

But it doesn’t have any effect in my case, Location header still have http instead of https and it looks like this directive is doing nothing. To be sure I added a new header and it is present in my response.

2. Error messages and/or full log output:

3. Caddy version:

2.8.4

4. How I installed and ran Caddy:

My caddy is running in Docker (custom Dockerfile)

a. System environment

docker

b. Command:

not important

c. Service/unit/compose file:

not important

d. My complete Caddy config:

{
  auto_https disable_certs # i'm using certs from static files
  admin off
}

*.mydomain.com {
  tls /etc/caddy/public.pem /etc/caddy/private.key {
    protocols tls1.2 tls1.3
    client_auth verify_if_given
  }

  handle /app* {
    reverse_proxy my-app.address.local:2222 {
      @redirect 301 302 303 307 308
      handle_response @redirect {
        header Custom-Header "Test"
        header Location http:// https://
        # also tried like:
        # header Location http https
        # or any other text in the location header - no effect
        copy_response # i'm not getting any response without this directive
      }
    }
  }
}

5. Links to relevant resources:

[francislavoie]

You don’t need handle_response for this, actually. Just the header directive is enough.

handle /app* {
	header >Location http:// https://
	reverse_proxy my-app.address.local:2222
}

But still, the correct fix is to get the upstream app to respect the X-Forwarded-Proto header to detect whether the original request was HTTPS or not.