Caddy
The configuration template shown below apply to both single-application and domain-level forward auth.
info
example-outpost is used as a placeholder for the outpost name. authentik.company is used as a placeholder for the authentik install. app.company is used as a placeholder for the external domain for the application. outpost.company is used as a placeholder for the outpost. When using the embedded outpost, this can be the same as authentik.company
- Caddy (standalone)
 
Use the following configuration:
app.company {
    # directive execution order is only as stated if enclosed with route.
    route {
        # always forward outpost path to actual outpost
        reverse_proxy /outpost.goauthentik.io/* http://outpost.company:9000
        # forward authentication to outpost
        forward_auth http://outpost.company:9000 {
            uri /outpost.goauthentik.io/auth/caddy
            # capitalization of the headers is important, otherwise they will be empty
            copy_headers X-Authentik-Username X-Authentik-Groups X-Authentik-Entitlements X-Authentik-Email X-Authentik-Name X-Authentik-Uid X-Authentik-Jwt X-Authentik-Meta-Jwks X-Authentik-Meta-Outpost X-Authentik-Meta-Provider X-Authentik-Meta-App X-Authentik-Meta-Version
            # optional, in this config trust all private ranges, should probably be set to the outposts IP
            trusted_proxies private_ranges
        }
        # actual site configuration below, for example
        reverse_proxy localhost:1234
    }
}
If you're trying to proxy to an upstream over HTTPS, you need to set the Host header to the value they expect for it to work correctly.
reverse_proxy /outpost.goauthentik.io/* https://outpost.company {
    header_up Host {http.reverse_proxy.upstream.host}
}