Nova logs shouldn’t have ERRORs or TRACEs in them

Nova logs shouldn’t have ERRORs or TRACEs in them

https://blueprints.launchpad.net/nova/+spec/clean-logs

Nova logs should be readable, sensible, and contain only errors and traces in exceptional situations.

Problem description

During a normal, successful, run of Tempest in the OpenStack gate we get a large number of ERRORs and stack traces in the logs. This is for passing results, which means the cloud should have been operating normally.

Stack traces and errors in the logs under normal conditions make it very difficult for operators to actually determine when real issues are happening with their OpenStack cloud. We’ve seen this even as part of normal development where people will be tricked in debugging OpenStack issues by the ERRORs, when the real issue is masked.

Proposed change

We should clean up all the instances of Stack Traces and Errors happening under a normal Tempest run. This means addressing the bugs that this currently exposes, as well as changing some logging levels where we are logging Exceptions at log.exception level that are actually expected (and thus should be a log.debug or deleted entirely).

See Testing section below for completion criteria.

Alternatives

None.

Data model impact

None.

REST API impact

None.

Security impact

None.

Notifications impact

None.

Other end user impact

This will change some log messages for clarity. Users that built filters around the old error messages will have to adjust their filters. As they were probably filtering those messages out, this should be minimal.

Performance Impact

None. (Possibly miniscule, and largely undetectable, boost because of not dumping stack traces so much.)

Other deployer impact

None.

Developer impact

Developers will have to be more careful about doing arbitrary log.exception calls inside Nova code once this is enforcing, and will need to be more careful on catching appropriate exceptions for expected conditions.

Implementation

Assignee(s)

Primary assignee:

sdague

Work Items

The services should be tackled in this order (consider cleaning of each one a work item):

  • n-sched

  • n-net

  • n-api

  • n-cpu

n-sched and n-net are currently the most critical to clean up as they are services that surface testing don’t hit directly (only indirectly through n-api calls). Ensuring that they don’t have unexpect behavior in dumping stack traces will provide extra verification that those services are working as expected.

Dependencies

None

Testing

Testing will be accomplished by the tempest check_logs.py script currently running in the gate. Once we are confident that we have cleaned up a service, we remove that service from the allowed_dirty list https://github.com/openstack/tempest/blob/master/tools/check_logs.py#L33. After that any change which causes there to be a stack trace or error in the logs for that service will cause the tempest tests to fail, thus blocking the change from merging.

Documentation Impact

There will be a related effort in overall logging standards (to be presented as a Juno cross project session) that will need to be fleshed out in conjunction with this.

Creative Commons Attribution 3.0 License

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.

nova-specs