Proposal: Use Prometheus labels in stats_over_http plugin output

[itsh3sam]

I'm considering contributing a PR to change the Prometheus output in the stats_over_http plugin to use metric labels instead of flattening all metric names. This would provide a more standard Prometheus format and make metric parsing and aggregation much easier for users and downstream tools.

Is it acceptable to prepare a PR for this change? Are there any reasons this approach wouldn't be welcome (compatibility concerns, past discussions, etc.)? If so, should it be opt-in or the default format?

[masaori335]

Sounds nice, but did you check the /_stats/prometheus output format? It's different from your proposal?

https://docs.trafficserver.apache.org/admin-guide/plugins/stats_over_http.en.html#output-format

[itsh3sam]

Yes, I’ve reviewed the current /_stats/prometheus format and docs.
Instead of encoding dimensions into the metric name (e.g. proxy_process_http_303_responses or proxy_process_api_time_10ms), I’m suggesting using Prometheus labels:

proxy_process_http_responses{status="303"}
proxy_process_api_time{le="10"}

This follows Prometheus best practices, avoids metric name explosion, and makes querying and aggregation much easier.