Decide what exposition formats to support

[TonyRippy]

I'm not sure what to do with OpenMetrics. What exposition formats should these tools support? Prometheus, OpenMetrics, or both?

[TonyRippy]

For what it's worth, here are notes from some experimentation I had done in the past. It seems like you can request a specific exposition format from the Prometheus Go client library using the HTTP Accept header.

To get the OpenMetrics exposition format, I think you're supposed to use the following:

curl -H "Accept: application/openmetrics-text; version=1.0.0; charset=utf-8" http://localhost:9100/metrics

... but it doesn't seem like it works with Node Exporter? The node_vmstat_pswpin metric shows up as "untyped", which according to the OpenMetrics spec is supposed to be "unknown". (link)

For the (deprecated?) Protobuf format, use one of the following:

curl -H "Accept: application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=text" http://localhost:9100/metrics

The options for the encoding parameter are:

• encoding=text = Formatted protobufs, best for human reading.
• encoding=compact-text = Text formatted protobufs, with one metric family per line.
• encoding=delimited = Binary protobuf. (I think, haven't verified.)