Preserving timestamps for prometheus exporter

[nishkrishnan]

I see here that timestamps were explicitly removed from the prometheus exporter. However, shouldn't this be a setting for the user that allows them to choose whether timestamps should be honored or not?

In my case I want to preserve the timestamps that come from the source. How can I achieve that currently?

[owent]

The time setting is now restored in the latest version and is derived from the metrics data. Exporters should only handle I/O; if you need to modify metrics data, please implement a custom processor.

[dashpole]

You can see the original issue here: #2316. Unless you are re-exposing metrics from another source with significantly different timestamps, you should not add them. I'm not opposed to having an option to enable explicit timestamps, but we should make sure we define it in the spec here so that languages use similar names for the option.