Nginx 5xx rate too high for many apps/boxes
If the message is “UNKNOWN: INTERNAL ERROR: RuntimeError: no valid
datapoints” or “UNKNOWN: INTERNAL ERROR: RuntimeError: no data returned
for target”, it probably means that statsd or collectd stopped
submitting data for a period. Statsd metrics (those that begin with
stats.) don’t get created until the first event of a given type. For
infrequently-used apps which rarely have errors, the
never get created. You can force creation by creating a zero-value
fab $environment -H frontend-1.frontend statsd.create_counter:frontend-1_frontend.nginx_logs.static_publishing_service_gov_uk.http_500
Note that the
http_5xx counters are created by carbon-aggregator, so
they will automatically be created when a corresponding
counter gets created. You should not create a statsd counter for
http_5xx as this will confuse carbon-aggregator.
For collectd metrics (those without a leading
stats. prefix), you
probably just need to wait for the metric to get created.
The alert should link to a graphite graph - often certain applications such as Whitehall can have spikes - if you can determine this is a spike it is best to acknowledge the alert and let the team that owns the app know.