Timestamps should be in seconds, eg in setToCurrentTime methods

[kamalmarhubi]

The implementation of setToCurrentTime for gauges uses the value of Date.now() which is in milliseconds. The suggested conventions for client libraries is to use base units for all recorded metrics.

[SimenB]

Very good point. Mind sending a PR for it? It's a breaking change, but that's fine. It will match the java client: https://github.com/prometheus/client_java/blob/1a8bf7da57402f444861c32abc9e0c7cd313748e/simpleclient/src/main/java/io/prometheus/client/Gauge.java#L178-L180

[siimon]

Oh that one slipped under the radar! If you create a PR don't forget the change log :)

[kamalmarhubi]

This can be done without breakage by adding a default-true flag legacyCurrentTimeMilliseconds on gauges. The flag can be set to false by people like me who want seconds. A breaking change can flip the default, and a further one can remove it.

I will probably PR this soon.

[siimon]

I'm leaning towards making the breaking change right away instead of starting to add legacy properties, what do you think @SimenB ?

[SimenB]

+1 for just breaking. What we do now is wrong, I see no reason to keep supporting it

[kamalmarhubi]

Happy to do either! :-)