Collect recent error logs

If the logs are outputted by zap, error messages are aggregated by checking level = error. This log does not work very well if the field error contains some unique values like id.

$ kubectl logs -l key=value --since=5m | jq -r 'select(.level=="error") | .error' | sort | uniq -c | sort -bgr

Instead of error field, msg or errorVerbose could be used.