Roadmap suggestion: Prometheus integration

[udf2457]

First thank you for your work on this great project which I have only discovered today !

Could I put the idea in your minds to add Prometheus integration to irtt.

To be more specific:

• irtt-client support for Prometheus text-based exposition. This would enable irtt-client to publish output in a directory for collection by node_exporterwhen running with the --collector.textfile.directory flag; and/or
• irtt-server publish a http metrics page for Prometheus to scrape

Given that both irtt and prometheus are written in Go and prometheus publish Go libraries, I think this should be relatively straightforward to implement. I'm a noob to Go programming but even I managed to hack together something (for my own personal unrelated project) that exports to text file using the following calls from the Prometheus go library:

import (
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/expfmt"
)

# Create registry
reg := prometheus.NewRegistry()
var collectors []prometheus.Collector

# Gauge / Counters (Repeated as required)
gauge := prometheus.NewGauge(prometheus.GaugeOpts{}) 
gauge.Set(value)
collectors = append(
  collectors,
  gauge,
  )

# Collect and export to text file
reg.MustRegister(collectors...)
gathered, err := reg.Gather()
for _, item := range gathered {
  _, err := expfmt.MetricFamilyToText(
  tmp,
  item,
  )

[heistp]

It sounds like a useful addition, but I'm trying to do it keep the binary size down so irtt can be run on embedded devices.

If I compile the binary as is, the size is 3983781. If I compile referencing the prometheus libs, the size increases 10049128. So, it's not something I would add by default. It could be done with build tags. Another option is to write a separate program to take the json and do whatever you want to do with prometheus separately.

I'll leave the issue open in case someone wants to work on it...

[udf2457]

Re: Seperate program taking JSON, I did start experimenting with that, but quickly found it would be nice if irtt codebase was made more friendly for use as a go library.

For example, I thought I the obvious easy solution would be to Unmarshal into the JSON struct from your codebase, but that failed miserably ( I can't remember the error now since I abandoned that test code but something like "unable to unmarshal text into irtt.Time") so I ended up having to write up my own structs.

Also in general, making it easier to call measurement runs directly from go instead of having to call-out to exec.command()

[heistp]

Right, it could be useful. If someone writes it and keeps it opt-in with build tags I'll consider pulling that in...