Szenario: Coder/Code-Server hiner Nginx Proxy Manager, abgesichert durch forward_auth mit Authentik.

Irgendwie war es recht kompliziert an eine funktionierende Config im NPM zu kommen, die auch Websockets weiterreicht ..

Hier meine funktionierende Config

# Increase buffer size for large headers
# This is needed only if you get 'upstream sent too big header while reading response
# header from upstream' error when trying to access an application protected by goauthentik
proxy_buffers 8 16k;
proxy_buffer_size 32k;

# Make sure not to redirect traffic to a port 4443
port_in_redirect off;

location / {
    # Put your proxy_pass to your application here
    proxy_pass          $forward_scheme://$server:$port;
    # Set any other headers your application might need
    # proxy_set_header Host $host;
    # proxy_set_header ...
    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection upgrade;
    proxy_set_header Accept-Encoding gzip;

    ##############################
    # authentik-specific config
    ##############################
    auth_request     /outpost.goauthentik.io/auth/nginx;
    error_page       401 = @goauthentik_proxy_signin;
    auth_request_set $auth_cookie $upstream_http_set_cookie;
    add_header       Set-Cookie $auth_cookie;

    # translate headers from the outposts back to the actual upstream
    auth_request_set $authentik_username $upstream_http_x_authentik_username;
    auth_request_set $authentik_groups $upstream_http_x_authentik_groups;
    auth_request_set $authentik_entitlements $upstream_http_x_authentik_entitlements;
    auth_request_set $authentik_email $upstream_http_x_authentik_email;
    auth_request_set $authentik_name $upstream_http_x_authentik_name;
    auth_request_set $authentik_uid $upstream_http_x_authentik_uid;

    proxy_set_header X-authentik-username $authentik_username;
    proxy_set_header X-authentik-groups $authentik_groups;
    proxy_set_header X-authentik-entitlements $authentik_entitlements;
    proxy_set_header X-authentik-email $authentik_email;
    proxy_set_header X-authentik-name $authentik_name;
    proxy_set_header X-authentik-uid $authentik_uid;
}

location /outpost.goauthentik.io {
    # When using the embedded outpost, use:
    proxy_pass              http://{AUTHENTIK_SERVER_GOES_HERE}:9000/outpost.goauthentik.io;
    # For manual outpost deployments:
    # proxy_pass              http://outpost.company:9000;

    # Note: ensure the Host header matches your external authentik URL:
    proxy_set_header        Host $host;

    proxy_set_header        X-Original-URL $scheme://$http_host$request_uri;
    add_header              Set-Cookie $auth_cookie;
    auth_request_set        $auth_cookie $upstream_http_set_cookie;
    proxy_pass_request_body off;
    proxy_set_header        Content-Length "";
}

location @goauthentik_proxy_signin {
    internal;
    add_header Set-Cookie $auth_cookie;
    return 302 /outpost.goauthentik.io/start?rd=$scheme://$http_host$request_uri;
}