dashboard: show unhandled HumanReadableExceptions on http500 page

circle/circle/urls.py

@@ -64,3 +64,5 @@ if get_env_variable('DJANGO_SAML', 'FALSE') == 'TRUE':
         '',
         (r'^saml2/', include('djangosaml2.urls')),
     )
+
+handler500 = 'common.views.handler500'

circle/common/views.py

+from sys import exc_info
+
+import logging
+
+from django.template import RequestContext
+from django.shortcuts import render_to_response
+
+from .models import HumanReadableException
+
+logger = logging.getLogger(__name__)
+
+
+def handler500(request):
+    cls, exception, traceback = exc_info()
+    logger.exception("unhandled exception")
+    ctx = {}
+    if isinstance(exception, HumanReadableException):
+        try:
+            ctx['error'] = exception.get_user_text()
+        except:
+            pass
+        else:
+            try:
+                if request.user.is_superuser():
+                    ctx['error'] = exception.get_admin_text()
+            except:
+                pass
+        try:
+            resp = render_to_response("500.html", ctx, RequestContext(request))
+        except:
+            resp = render_to_response("500.html", ctx)
+        resp.status_code = 500
+        return resp

circle/templates/500.html

-{% extends "base.html" %}
+{% extends "dashboard/base.html" %}
 {% load i18n %}
 
 {% block title %}HTTP 500{% endblock %}
@@ -6,5 +6,11 @@
 {% block page_title %}{% trans ":(" %}{% endblock page_title %}
 
 {% block content %}
+<div style="margin-top: 4em;">
+{% if error %}
+<p>{{ error }}</p>
+{% else %}
 <p>{% trans "Internal Server Error... Please leave the server alone..." %}</p>
+{% endif %}
+</div>
 {% endblock content %}