From c7f2325a0cf17e21326f5428691cc398dc25ccd9 Mon Sep 17 00:00:00 2001
From: Dillon Hardy <dhardy@wikimedia.org>
Date: Thu, 28 Aug 2025 15:56:07 -0400
Subject: [PATCH 1/2] Add custom 4xx/5xx error page templates

https://phabricator.wikimedia.org/T350820
---
 docker-compose.yml              |  3 +++
 extlinks/templates/400.html     |  8 +++++++
 extlinks/templates/403.html     |  8 +++++++
 extlinks/templates/404.html     |  8 +++++++
 extlinks/templates/500/500.html | 42 +++++++++++++++++++++++++++++++++
 extlinks/urls.py                |  5 ++++
 nginx.conf                      | 10 ++++++++
 7 files changed, 84 insertions(+)
 create mode 100644 extlinks/templates/400.html
 create mode 100644 extlinks/templates/403.html
 create mode 100644 extlinks/templates/404.html
 create mode 100644 extlinks/templates/500/500.html
diff --git a/docker-compose.yml b/docker-compose.yml
index 5e019793..badda269 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -88,6 +88,9 @@ services:
       - type: bind
         source: ./static
         target: /app/static
+      - type: bind
+        source: ./extlinks/templates/500
+        target: /app/500
     ports:
       - "80:80"
     depends_on:
diff --git a/extlinks/templates/400.html b/extlinks/templates/400.html
new file mode 100644
index 00000000..809427a1
--- /dev/null
+++ b/extlinks/templates/400.html
@@ -0,0 +1,8 @@
+{% extends 'base.html' %}
+
+{% block content %}
+<div class="body">
+    <h1>400 Bad Request</h1>
+    <p>Sorry; we don't know what to do with that.</p>
+</div>
+{% endblock %}
diff --git a/extlinks/templates/403.html b/extlinks/templates/403.html
new file mode 100644
index 00000000..429f32b8
--- /dev/null
+++ b/extlinks/templates/403.html
@@ -0,0 +1,8 @@
+{% extends 'base.html' %}
+
+{% block content %}
+<div class="body">
+    <h1>403 Forbidden</h1>
+    <p>Sorry; you aren't allowed to do that.</p>
+</div>
+{% endblock %}
diff --git a/extlinks/templates/404.html b/extlinks/templates/404.html
new file mode 100644
index 00000000..766b6f65
--- /dev/null
+++ b/extlinks/templates/404.html
@@ -0,0 +1,8 @@
+{% extends 'base.html' %}
+
+{% block content %}
+<div class="body">
+    <h1>404 Not Found</h1>
+    <p>Sorry; we can't find that.</p>
+</div>
+{% endblock %}
diff --git a/extlinks/templates/500/500.html b/extlinks/templates/500/500.html
new file mode 100644
index 00000000..6feb1977
--- /dev/null
+++ b/extlinks/templates/500/500.html
@@ -0,0 +1,42 @@
+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <meta charset="utf-8">
+        <meta name="viewport" content="width=device-width, initial-scale=1">
+
+        <title>Wikimedia External Links Tool</title>
+
+        <link rel="icon" type="image/png" href="/static/favicon.ico">
+        <link rel="stylesheet" href="https://tools-static.wmflabs.org/cdnjs/ajax/libs/twitter-bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
+        <link rel="stylesheet" href="/static/css/local.css" type="text/css">
+    </head>
+
+    <body>
+        <nav class="navbar navbar-expand-lg navbar-light shadow-sm">
+            <a class="navbar-brand" href="/">Wikilink</a>
+            <div class="navbar-nav">
+                <a class="nav-item nav-link" href="/programs/">Programs</a>
+                <a class="nav-item nav-link" href="/organisations/">Organisations</a>
+                <a class="nav-item nav-link" href="/docs">What is this?</a>
+            </div>
+        </nav>
+
+        <div class="main-content">
+            <div class="body">
+                <h1>500 Internal Server Error</h1>
+                <p>Sorry; something went wrong.</p>
+            </div>
+        </div>
+
+        <hr/>
+
+        <div class="footer">
+            A <a href="https://meta.wikimedia.org/wiki/The_Wikipedia_Library">Wikipedia Library</a> project -
+            <a href="https://github.com/WikipediaLibrary/externallinks">Github</a> -
+            <a href="https://phabricator.wikimedia.org/project/board/4082/">Phabricator</a> -
+            <a href="https://meta.wikimedia.org/wiki/Wikilink_tool">Meta</a>
+        </div>
+
+        <script type="text/javascript" src="https://tools-static.wmflabs.org/cdnjs/ajax/libs/twitter-bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
+    </body>
+</html>
diff --git a/extlinks/urls.py b/extlinks/urls.py
index e29f8e3e..75a0b023 100644
--- a/extlinks/urls.py
+++ b/extlinks/urls.py
@@ -2,6 +2,7 @@
 from django.contrib import admin
 from django.urls import include, path
 from django.conf import settings
+from django.views.generic import TemplateView
 
 from extlinks.healthcheck.urls import urlpatterns as healthcheck_urls
 from extlinks.programs.urls import urlpatterns as programs_urls
@@ -31,4 +32,8 @@
 
         urlpatterns += [
             path("__debug__/", include(debug_toolbar.urls)),
+            path("400/", TemplateView.as_view(template_name="400.html")),
+            path("403/", TemplateView.as_view(template_name="403.html")),
+            path("404/", TemplateView.as_view(template_name="404.html")),
+            path("500/", TemplateView.as_view(template_name="500/500.html")),
         ]
diff --git a/nginx.conf b/nginx.conf
index aca3f0d6..e09a62a7 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -80,6 +80,7 @@ server {
     # checks for static file, if not found proxy to app
     try_files $uri @django;
   }
+
   location @django {
     # Cache
     proxy_cache_valid 200 301 302 401 403 404 1d;
@@ -97,6 +98,7 @@ server {
     proxy_redirect off;
     proxy_pass http://django_server;
   }
+
   location @django-admin-slow {
     # https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_send_timeout
     proxy_connect_timeout 120s;
@@ -121,4 +123,12 @@ server {
     proxy_redirect off;
     proxy_pass http://django_server;
   }
+
+  proxy_intercept_errors on;
+  error_page 500 501 502 503 504 505 506 /500.html;
+
+  location = /500.html {
+    root /app/500;
+    internal;
+  }
 }

From a5458550966e23e89627b443e6db11cb7941a385 Mon Sep 17 00:00:00 2001
From: Dillon Hardy <dhardy@wikimedia.org>
Date: Thu, 28 Aug 2025 15:56:07 -0400
Subject: [PATCH 2/2] Added custom 500 view handler in Django

---
 extlinks/urls.py  | 2 ++
 extlinks/views.py | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/extlinks/urls.py b/extlinks/urls.py
index 75a0b023..6daef1a0 100644
--- a/extlinks/urls.py
+++ b/extlinks/urls.py
@@ -10,6 +10,8 @@
 
 from .views import Homepage, Documentation
 
+handler500 = "extlinks.views.custom_server_error"
+
 urlpatterns = [
     path("admin/", admin.site.urls),
     path("", Homepage.as_view(), name="homepage"),
diff --git a/extlinks/views.py b/extlinks/views.py
index 77ecbd01..aad600d8 100644
--- a/extlinks/views.py
+++ b/extlinks/views.py
@@ -1,4 +1,6 @@
+from django.views.decorators.csrf import requires_csrf_token
 from django.views.generic import TemplateView
+from django.views.defaults import server_error
 
 
 class Homepage(TemplateView):
@@ -7,3 +9,7 @@ class Homepage(TemplateView):
 
 class Documentation(TemplateView):
     template_name = "documentation.html"
+
+@requires_csrf_token
+def custom_server_error(request):
+    return server_error(request, "500/500.html")
