Don't fail on missing change_queues key in status json

Since the pipeline state is stored in ZooKeeper, there could be cases
where the change_queues key is missing in the status json. This makes
API requests fail:

2022-02-22 17:56:18,390 ERROR cherrypy.error.139989033522128: [22/Feb/2022:17:56:18] HTTP
Traceback (most recent call last):
  File "/opt/zuul/lib/python3.8/site-packages/cherrypy/_cprequest.py", line 638, in respond
    self._do_respond(path_info)
  File "/opt/zuul/lib/python3.8/site-packages/cherrypy/_cprequest.py", line 697, in _do_respond
    response.body = self.handler()
  File "/opt/zuul/lib/python3.8/site-packages/cherrypy/lib/encoding.py", line 223, in __call__
    self.body = self.oldhandler(*args, **kwargs)
  File "/opt/zuul/lib/python3.8/site-packages/cherrypy/lib/jsontools.py", line 59, in json_handler
    value = cherrypy.serving.request._json_inner_handler(*args, **kwargs)
  File "/opt/zuul/lib/python3.8/site-packages/cherrypy/_cpdispatch.py", line 54, in __call__
    return self.callable(*self.args, **self.kwargs)
  File "/opt/zuul/lib/python3.8/site-packages/zuul/web/__init__.py", line 1050, in status_change
    return result_filter.filterPayload(payload)
  File "/opt/zuul/lib/python3.8/site-packages/zuul/web/__init__.py", line 193, in filterPayload
    for change_queue in pipeline['change_queues']:
KeyError: 'change_queues'

Fix this by using a .get() call rather than directly accessing the
dictionary key by name.

A similar issue was already fixed in [1].

[1]: https://review.opendev.org/c/zuul/zuul/+/829018

Change-Id: I947f58f02c3da7dad35d1fc186c7026800f7cbdd

2 files changed, 2 insertions, 2 deletions

diff --git a/tools/zuul-changes.py b/tools/zuul-changes.py
index 96aeb88f2..05f7fb33f 100755
--- a/tools/zuul-changes.py
+++ b/tools/zuul-changes.py
@@ -63,7 +63,7 @@ for tenant in tenants:
     for pipeline in data['pipelines']:
         if options.pipeline and pipeline['name'] != options.pipeline:
             continue
-        for queue in pipeline['change_queues']:
+        for queue in pipeline.get('change_queues', []):
             for head in queue['heads']:
                 for change in head:
                     if not change['live']:
diff --git a/zuul/web/__init__.py b/zuul/web/__init__.py
index a3f7dcbcc..b92ccabea 100755
--- a/zuul/web/__init__.py
+++ b/zuul/web/__init__.py
@@ -207,7 +207,7 @@ class ChangeFilter(object):
     def filterPayload(self, payload):
         status = []
         for pipeline in payload['pipelines']:
-            for change_queue in pipeline['change_queues']:
+            for change_queue in pipeline.get('change_queues', []):
                 for head in change_queue['heads']:
                     for change in head:
                         if self.wantChange(change):