Big Picture

Epimetheus is a functional API placed over the underyling Prometheus Java Client.

This underlying library has little to no type-safety and safe interactions, the primary issues are

1. Invalid Collector Registration

2. Allowing references to be invalidated.

3. Applying a different number of labels, from the labels on the Collector

4. Invalid arguments for constructors. Such as an invalid Quantile.

Generalized Solutions

Across all metrics we solve these problems with a few solutions.

1. Registration is always done in an effect. If two collectors with the same name are registered, it will fail at registration. If you are building custom groups of Collectors, exposing a prefix that can be altered is suggested in case users wish to register more than one.

2. We hide all reference invalidation components of the underlying API.

3. We utilize Sized from Shapeless to guarantee at compile time that the labels applied to the Metric are the same size as the labels in the Metric.

4. We provide safe constructors for arguments, such as Name and Quantile.