From 2a784ec46f783ad85b55c48a8a1663ff22544d28 Mon Sep 17 00:00:00 2001
From: eyjhb <eyjhbb@gmail.com>
Date: Mon, 12 Aug 2024 23:34:59 +0200
Subject: [PATCH] gerd.authelia: added
 `mine.shared.lib.authelia.mkProtectedWebsite

Adds authelia in front of any website given, that only members can access
---
 .../gerd/services/authelia/authelia-nginx.nix | 120 ++++++++++--------
 machines/gerd/services/authelia/default.nix   |   2 +-
 2 files changed, 68 insertions(+), 54 deletions(-)

diff --git a/machines/gerd/services/authelia/authelia-nginx.nix b/machines/gerd/services/authelia/authelia-nginx.nix
index 6c3e6b3..9a13625 100644
--- a/machines/gerd/services/authelia/authelia-nginx.nix
+++ b/machines/gerd/services/authelia/authelia-nginx.nix
@@ -1,81 +1,95 @@
-{ pkgs, ... }:
+{ config, lib, pkgs, ... }:
 
 # most is taken from this discussion https://www.reddit.com/r/NixOS/comments/15trmac/how_would_you_do_a_nginx_snippets_in_nixos/
 # with the following gist https://gist.github.com/aswan89/ee554406c39eb2eeb3126f73f74ab61c
+# updated from the following page, with inspiration from the gist
+# https://www.authelia.com/integration/proxies/nginx/
 let
   AUTHELIA_HOST = "http://localhost:9091";
 
   autheliaLocation = pkgs.writeText "authelia-location.conf" ''
-    ## Essential Proxy Configuration
-    internal;
-    proxy_pass ${AUTHELIA_HOST}/api/verify;
-    ## Headers
-    ## The headers starting with X-* are required.
-    proxy_set_header X-Original-URL $scheme://$http_host$request_uri;
-    proxy_set_header X-Original-Method $request_method;
-    proxy_set_header X-Forwarded-Method $request_method;
-    proxy_set_header X-Forwarded-Proto $scheme;
-    proxy_set_header X-Forwarded-Host $http_host;
-    proxy_set_header X-Forwarded-Uri $request_uri;
-    proxy_set_header X-Forwarded-For $remote_addr;
-    proxy_set_header Content-Length "";
-    proxy_set_header Connection "";
-    ## Basic Proxy Configuration
-    proxy_pass_request_body off;
-    proxy_next_upstream error timeout invalid_header http_500 http_502 http_503; # Timeout if the real server is dead
-    proxy_redirect http:// $scheme://;
-    proxy_http_version 1.1;
-    proxy_cache_bypass $cookie_session;
-    proxy_no_cache $cookie_session;
-    proxy_buffers 4 32k;
-    client_body_buffer_size 128k;
-    ## Advanced Proxy Configuration
-    send_timeout 5m;
-    proxy_read_timeout 240;
-    proxy_send_timeout 240;
-    proxy_connect_timeout 240;
+    ## Virtual endpoint created by nginx to forward auth requests.
+    location /authelia {
+        ## Essential Proxy Configuration
+        internal;
+        proxy_pass ${AUTHELIA_HOST}/api/verify;
+    
+        ## Headers
+        ## The headers starting with X-* are required.
+        proxy_set_header X-Original-Method $request_method;
+        proxy_set_header X-Original-URL $scheme://$http_host$request_uri;
+        proxy_set_header X-Forwarded-For $remote_addr;
+        proxy_set_header Content-Length "";
+        proxy_set_header Connection "";
+    
+        ## Basic Proxy Configuration
+        proxy_pass_request_body off;
+        proxy_next_upstream error timeout invalid_header http_500 http_502 http_503; # Timeout if the real server is dead
+        proxy_redirect http:// $scheme://;
+        proxy_http_version 1.1;
+        proxy_cache_bypass $cookie_session;
+        proxy_no_cache $cookie_session;
+        proxy_buffers 4 32k;
+        client_body_buffer_size 128k;
+    
+        ## Advanced Proxy Configuration
+        send_timeout 5m;
+        proxy_read_timeout 240;
+        proxy_send_timeout 240;
+        proxy_connect_timeout 240;
+    }
   '';
+
   autheliaRequest = pkgs.writeText "authelia-authrequest.conf" ''
-    ### goes inside a location block to make the request to authelia
     ## Send a subrequest to Authelia to verify if the user is authenticated and has permission to access the resource.
     auth_request /authelia;
-    ## Set the $target_url variable based on the original request.
-    ## Comment this line if you're using nginx without the http_set_misc module.
-    #set_escape_uri $target_url $scheme://$http_host$request_uri;
-    ## Uncomment this line if you're using NGINX without the http_set_misc module.
-    set $target_url $scheme://$http_host$request_uri;
-    ## Save the upstream response headers from Authelia to variables.
+    
+    ## Save the upstream metadata response headers from Authelia to variables.
     auth_request_set $user $upstream_http_remote_user;
     auth_request_set $groups $upstream_http_remote_groups;
     auth_request_set $name $upstream_http_remote_name;
     auth_request_set $email $upstream_http_remote_email;
-    ## Inject the response headers from the variables into the request made to the backend.
+    
+    ## Inject the metadata response headers from the variables into the request made to the backend.
     proxy_set_header Remote-User $user;
     proxy_set_header Remote-Groups $groups;
-    proxy_set_header Remote-Name $name;
     proxy_set_header Remote-Email $email;
-        ## If the subreqest returns 200 pass to the backend, if the subrequest returns 401 redirect to the portal.
+    proxy_set_header Remote-Name $name;
+    
+    ## Configure the redirection when the authz failure occurs. Lines starting with 'Modern Method' and 'Legacy Method'
+    ## should be commented / uncommented as pairs. The modern method uses the session cookies configuration's authelia_url
+    ## value to determine the redirection URL here. It's much simpler and compatible with the mutli-cookie domain easily.
+    
+    ## Modern Method: Set the $redirection_url to the Location header of the response to the Authz endpoint.
+    # auth_request_set $redirection_url $upstream_http_location;
+    
+    ## Modern Method: When there is a 401 response code from the authz endpoint redirect to the $redirection_url.
+    # error_page 401 =302 $redirection_url;
+    
+    ## Legacy Method: Set $target_url to the original requested URL.
+    ## This requires http_set_misc module, replace 'set_escape_uri' with 'set' if you don't have this module.
+    # set_escape_uri $target_url $scheme://$http_host$request_uri;
+    set $target_url $scheme://$http_host$request_uri;
+    
+    ## Legacy Method: When there is a 401 response code from the authz endpoint redirect to the portal with the 'rd'
+    ## URL parameter set to $target_url. This requires users update 'auth.example.com/' with their external authelia URL.
     error_page 401 =302 https://auth.fricloud.dk/?rd=$target_url;
   '';
 in {
-  services.nginx.virtualHosts."test.fricloud.dk" = {
+  mine.shared.lib.authelia.mkProtectedWebsite = virtualHostConfig: lib.recursiveUpdate {
     forceSSL = true;
     enableACME = true;
 
-    locations."/authelia" = {
-      recommendedProxySettings = false;
-      extraConfig = ''
-        include ${autheliaLocation};
-      '';
-    };
-    locations."/" = {
-      root = pkgs.writeTextDir "index.html" ''
-        ACCESS GRANTED!
-      '';
+    extraConfig = "include ${autheliaLocation};";
 
-      extraConfig = ''
-        include ${autheliaRequest};
-      '';
+    locations."/" = {
+      extraConfig = "include ${autheliaRequest};";
     };
+  } virtualHostConfig;
+
+  services.nginx.virtualHosts."test.fricloud.dk" = config.mine.shared.lib.authelia.mkProtectedWebsite {
+    locations."/".root = pkgs.writeTextDir "index.html" ''
+      ACCESS GRANTED!
+    '';
   };
 }
diff --git a/machines/gerd/services/authelia/default.nix b/machines/gerd/services/authelia/default.nix
index eaf3b4f..2576964 100644
--- a/machines/gerd/services/authelia/default.nix
+++ b/machines/gerd/services/authelia/default.nix
@@ -1,6 +1,6 @@
 {
   imports = [
     ./authelia.nix
-    # ./authelia-nginx.nix
+    ./authelia-nginx.nix
   ];
 }