Contextualize 404 page

readthedocs/core/views/__init__.py

@@ -48,6 +48,26 @@ def get_context_data(self, **kwargs):
         return context
 
 
+def server_error_404(request, template_name="404.html", exception=None):
+    """A simple 404 handler."""
+    # This property is set by ProxitoHttp404. We could also have a look at the
+    # subproject_slug
+    project_slug = getattr(exception, "project_slug", None)
+    log.debug(exception)
+    project = getattr(exception, "project", None)
+    log.debug(
+        "404 page detected a project slug in request.",
+        project_slug=project_slug,
+    )
+    r = render(
+        request,
+        template_name,
+        context={"project": project, "project_slug": project_slug},
+    )
+    r.status_code = 404
+    return r
+
+
 def server_error_500(request, template_name='500.html'):
     """A simple 500 handler so we get media."""
     r = render(request, template_name)

readthedocs/proxito/exceptions.py

@@ -0,0 +1,9 @@
+from django.http.response import Http404
+
+
+class ProxitoHttp404(Http404):
+    def __init__(self, message, project_slug=None, project=None, subproject_slug=None):
+        self.project_slug = project_slug
+        self.project = project
+        self.subproject_slug = subproject_slug
+        super().__init__(message)

readthedocs/proxito/views/decorators.py

@@ -1,9 +1,9 @@
-import structlog
 from functools import wraps
 
-from django.http import Http404
+import structlog
 
 from readthedocs.projects.models import Project, ProjectRelationship
+from readthedocs.proxito.exceptions import ProxitoHttp404
 
 log = structlog.get_logger(__name__)  # noqa
 
@@ -44,7 +44,9 @@ def inner_view(  # noqa
                         subproject_slug=subproject_slug,
                         project_slug=kwargs['project'].slug,
                     )
-                    raise Http404('Invalid subproject slug')
+                    raise ProxitoHttp404(
+                        "Invalid subproject slug", subproject_slug=subproject_slug
+                    )
         return view_func(request, subproject=subproject, *args, **kwargs)
 
     return inner_view
@@ -74,7 +76,13 @@ def inner_view(  # noqa
             try:
                 project = Project.objects.get(slug=project_slug)
             except Project.DoesNotExist:
-                raise Http404('Project does not exist.')
+                log.debug(
+                    "Project not found.",
+                    project_slug=project_slug,
+                )
+                raise ProxitoHttp404(
+                    "Project does not exist.", project_slug=project_slug
+                )
         return view_func(request, project=project, *args, **kwargs)
 
     return inner_view

readthedocs/proxito/views/serve.py

@@ -4,7 +4,7 @@
 
 import structlog
 from django.conf import settings
-from django.http import Http404, HttpResponse, HttpResponseRedirect
+from django.http import HttpResponse, HttpResponseRedirect
 from django.shortcuts import render
 from django.urls import resolve as url_resolve
 from django.utils.decorators import method_decorator
@@ -22,6 +22,7 @@
 from readthedocs.projects.constants import SPHINX_HTMLDIR
 from readthedocs.projects.models import Feature
 from readthedocs.projects.templatetags.projects_tags import sort_version_aware
+from readthedocs.proxito.exceptions import ProxitoHttp404
 from readthedocs.redirects.exceptions import InfiniteRedirectException
 from readthedocs.storage import build_media_storage, staticfiles_storage
 
@@ -109,7 +110,7 @@ def get(self,
         # version on the database we want to return 404.
         if (version and not version.active) or (version_slug and not version):
             log.warning("Version does not exist or is not active.")
-            raise Http404("Version does not exist or is not active.")
+            raise ProxitoHttp404("Version does not exist or is not active.")
 
         if self._is_cache_enabled(final_project) and version and not version.is_private:
             # All public versions can be cached.
@@ -174,7 +175,7 @@ def get(self,
                 'Invalid URL for project with versions.',
                 filename=filename,
             )
-            raise Http404('Invalid URL for project with versions')
+            raise ProxitoHttp404("Invalid URL for project with versions")
 
         redirect_path, http_status = self.get_redirect(
             project=final_project,
@@ -261,17 +262,25 @@ def get(self, request, proxito_path, template_name='404.html'):
             proxito_path,
             urlconf='readthedocs.proxito.urls',
         )
+        log.debug("Resolved a URL.")
 
         version_slug = kwargs.get('version_slug')
         version_slug = self.get_version_from_host(request, version_slug)
-        final_project, lang_slug, version_slug, filename = _get_project_data_from_request(  # noqa
+        log.debug("Getting _get_project_data_from_request.")
+        (
+            final_project,
+            lang_slug,
+            version_slug,
+            filename,
+        ) = _get_project_data_from_request(  # noqa
             request,
             project_slug=kwargs.get('project_slug'),
             subproject_slug=kwargs.get('subproject_slug'),
             lang_slug=kwargs.get('lang_slug'),
             version_slug=version_slug,
             filename=kwargs.get('filename', ''),
         )
+        log.debug("Finished _get_project_data_from_request.")
 
         log.bind(
             project_slug=final_project.slug,
@@ -390,7 +399,13 @@ def get(self, request, proxito_path, template_name='404.html'):
             path=filename,
             full_path=proxito_path,
         )
-        raise Http404('No custom 404 page found.')
+        log.debug("Raising ProxitoHttp404")
+        raise ProxitoHttp404(
+            "No custom 404 page found.",
+            project=final_project,
+            project_slug=kwargs.get("project_slug"),
+            subproject_slug=kwargs.get("subproject_slug"),
+        )
 
     def _register_broken_link(self, project, version, path, full_path):
         try:
@@ -472,7 +487,7 @@ def get(self, request, project):
 
         if no_serve_robots_txt:
             # ... we do return a 404
-            raise Http404()
+            raise ProxitoHttp404()
 
         storage_path = project.get_storage_path(
             type_='html',
@@ -595,7 +610,7 @@ def changefreqs_generator():
             only_active=True,
         )
         if not public_versions.exists():
-            raise Http404
+            raise ProxitoHttp404()
 
         sorted_versions = sort_version_aware(public_versions)
 

readthedocs/proxito/views/utils.py

@@ -2,7 +2,10 @@
 
 import structlog
 from django.http import HttpResponse
-from django.shortcuts import get_object_or_404, render
+from django.shortcuts import render
+
+from readthedocs.projects.models import Project
+from readthedocs.proxito.exceptions import ProxitoHttp404
 
 from .decorators import map_project_slug, map_subproject_slug
 
@@ -30,11 +33,23 @@ def proxito_404_page_handler(request, exception=None, template_name='404.html'):
     """
 
     if request.resolver_match and request.resolver_match.url_name != 'proxito_404_handler':
+        log.debug("Displaying a 'fast 404'")
         return fast_404(request, exception, template_name)
 
-    resp = render(request, template_name)
-    resp.status_code = 404
-    return resp
+    project_slug = getattr(exception, "project_slug", None)
+    log.debug(exception)
+    project = getattr(exception, "project", None)
+    log.debug(
+        "404 page detected a project slug in request.",
+        project_slug=project_slug,
+    )
+    r = render(
+        request,
+        template_name,
+        context={"project": project, "project_slug": project_slug},
+    )
+    r.status_code = 404
+    return r
 
 
 @map_project_slug
@@ -70,9 +85,20 @@ def _get_project_data_from_request(
     if not lang_slug or lang_slug == current_project.language:
         final_project = current_project
     else:
-        final_project = get_object_or_404(
-            current_project.translations.all(), language=lang_slug
-        )
+        try:
+            final_project = current_project.translations.get(language=lang_slug)
+        except Project.DoesNotExist:
+            log.debug(
+                "Raising 404 for language slug",
+                lang_slug=lang_slug,
+                project_slug=current_project.slug,
+            )
+            raise ProxitoHttp404(
+                "Did not find translation",
+                project=current_project,
+                project_slug=current_project.slug,
+                subproject_slug=lang_slug,
+            )
 
     # Handle single version by grabbing the default version
     # We might have version_slug when we're serving a PR

readthedocs/settings/base.py

@@ -44,7 +44,7 @@ class CommunityBaseSettings(Settings):
     DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
 
     # Debug settings
-    DEBUG = True
+    DEBUG = False
     RTD_FORCE_SHOW_DEBUG_TOOLBAR = False
 
     @property
@@ -73,7 +73,7 @@ def SHOW_DEBUG_TOOLBAR(self):
     PRODUCTION_DOMAIN = 'readthedocs.org'
     PUBLIC_DOMAIN = None
     PUBLIC_DOMAIN_USES_HTTPS = False
-    USE_SUBDOMAIN = False
+    USE_SUBDOMAIN = True
     PUBLIC_API_URL = 'https://{}'.format(PRODUCTION_DOMAIN)
     RTD_INTERSPHINX_URL = 'https://{}'.format(PRODUCTION_DOMAIN)
     RTD_EXTERNAL_VERSION_DOMAIN = 'external-builds.readthedocs.io'

readthedocs/templates/404.html

@@ -3,7 +3,7 @@
 {% load i18n %}
 
 {% block title %}
-  {% trans "Maze Found" %}
+  {% trans "404 - Maze Found" %}
 {% endblock %}
 
 {% block header-wrapper %}
@@ -16,6 +16,46 @@
 {% block language-select-form %}{% endblock %}
 
 {% block content %}
+
+<h1>{% trans "404 - page not found" %}</h1>
+
+{% if project %}
+
+  {# project exists #}
+
+  <p>
+    {% blocktrans with project_slug=project.slug request_path=request.path %}You are browsing the documentation of "{{ project_slug }}". The page you are looking for at <code>{{ request.path }}</code> was not found.{% endblocktrans %}
+  </p>
+
+  <p>
+    {% blocktrans %}Documentation changes over time. Pages are moved around. You can try to navigate to <a href="/">the index page</a> of the project and use its navigation or search function to find a similar page.{% endblocktrans %}</p>
+
+  <h3>{% trans "Are you the project owner?" %}</h3>
+
+  <p>{% trans "Here are some tips to address 404 errors:" %}</p>
+
+  <ul>
+    <li>{% trans "Use custom 404 pages:" %} <a href="https://docs.readthedocs.io/en/latest/hosting.html#custom-not-found-404-pages">{% trans "Read more" %}»</a></li>
+    <li>{% trans "Create redirects when you move contents:" %} <a href="https://docs.readthedocs.io/en/stable/user-defined-redirects.html">{% trans "Read more" %}»</a></li>
+    <li>{% trans "Use rediraffe to manage redirects in Sphinx:" %} <a href="https://pypi.org/project/sphinxext-rediraffe/">{% trans "Read more" %}»</a></li>
+  </ul>
+
+{% elif "_proxito_404_" in request.path %}
+
+  {# we are looking at a 404 generated by proxito, we then know that the project itself doesn't exist or hasn't been built #}
+
+  <p>
+    {% blocktrans with project_slug=project_slug %}The project "{{ project_slug }}" that you are looking for either does not exist, has been deleted or does not yet have any valid builds.{% endblocktrans %}
+  </p>
+
+{% else %}
+
+  <p>{% trans "You have encountered a 404 on Read the Docs. You are either looking for a page that does not exist or a project that has been removed." %}</p>
+
+  <p>{% trans "If you believe this is a technical error, please contact our support:" %} <a href="{% url 'support' %}">{% trans "Go to support" %}»</a></p>
+
+{% endif %}
+
 <pre style="line-height: 1.25; white-space: pre;">
 
         \          SORRY            /

readthedocs/urls.py

@@ -13,12 +13,14 @@
     HomepageView,
     SupportView,
     do_not_track,
+    server_error_404,
     server_error_500,
 )
 from readthedocs.search.views import GlobalSearchView
 
 admin.autodiscover()
 
+handler404 = server_error_404
 handler500 = server_error_500
 
 basic_urls = [
@@ -128,6 +130,7 @@
         document_root=os.path.join(settings.MEDIA_ROOT, build_format),
     )
 debug_urls += [
+    path("404/", server_error_404),
     path(
         "style-catalog/",
         TemplateView.as_view(template_name="style_catalog.html"),