PEP333 does not require QUERY_STRING to be present. (prometheus#252)

daroot · brian-brazil · commit 4ba6c90ee481 · 2018-03-06T20:31:51.000Z
Ensure that if a WSGI server does not provide the QUERY_STRING in the
environ, that we don't throw an exception and cause a 500 to be returned
to the scraping client.
diff --git a/prometheus_client/exposition.py b/prometheus_client/exposition.py
@@ -34,7 +34,7 @@
 def make_wsgi_app(registry=core.REGISTRY):
     '''Create a WSGI app which serves the metrics from a registry.'''
     def prometheus_app(environ, start_response):
-        params = parse_qs(environ['QUERY_STRING'])
+        params = parse_qs(environ.get('QUERY_STRING', ''))
         r = registry
         if 'name[]' in params:
             r = r.restricted_registry(params['name[]'])
