Defined rules allow the creation of a derived metric. A defined metric is useful to calculate information based off of gathered data and expose it to the processor (for example, grapher cannot (easily) declare a metric expression, so by declaring it here you can make the derivation show up as any other metric).
define group_name metric = expression ;
- group_name The name of a group. The metric will be created inside this group. If the group doesn't exist, it will be created.
- metric The metric name in the group under which to expose the expression. If the group already holds a metric under this name, it will be replaced.
- expression An expression that yields a value for the metric.
define com.groupon.brands.requesthandlers.CountryBrandsFuzzySearchHandler qps =
rate(com.groupon.brands.requesthandlers.CountryBrandsFuzzySearchHandler Count);
Define a qps rate, based on a monotonic incrementing counter.
The resulting metric will be exposed as com.groupon.brands.requesthandlers.CountryBrandsFuzzySearchHandler qps.
match com.groupon.brands.requesthandlers.* as handler {
define ${handler} qps = rate(handler Count);
}
Define a qps rate for all endpoints, based on a monotonic incrementing counter.
Note that the left-hand-side of the expression uses the name resolution,
while the right-hand-side of the expression uses the normal resolution.
The resulting metric will be exposed on the same group, with the name qps.