On Friday, 17 April 2020 12:46:01 UTC+1, Alex Rosen wrote: > > This page > <https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/> > says: > "The $value variable holds the evaluated value of an alert instance." > > It would be great if this also included a more explicit definition, > because this definition isn't obvious to me. For example, if I have: > > > expr: sum(increase(some_counter[3h])) by (foo) < 1 > > > Which part of this is the $value? It can't be the entire expression, > because that's just a boolean value. Is it everything to the left of the > comparison operator? >
It *is* the value of the entire expression. The prometheus operator "a < b" gives the value of the left-hand side if it's less than b (scalar, or timeseries with exactly matching label set), or no result if not. See comparison operators <https://prometheus.io/docs/prometheus/latest/querying/operators/#comparison-binary-operators> . You can try this for yourself in the PromQL expression evaluator in the prometheus UI: e.g. rate(node_network_receive_bytes_total[2m]) > 10000 You'll see line segments where the condition is true, and gaps where it's false. [image: png1.png] There is another form: "a < bool b", which gives 0 for false and 1 for true. In that case, the timeseries always exists, and $value will be either 0 or 1 (which for alerts makes it less useful in annotations) -- You received this message because you are subscribed to the Google Groups "Prometheus Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/prometheus-users/859c335f-a765-4a23-b466-8c698de94c39%40googlegroups.com.
