Add process_release metric.

[mcdee]

PR description

Add a process_release metric containing release information. This shows up as following:

process_release{version="besu/v22.4.1-dev-fe8ad2d5/linux-x86_64/openjdk-java-11",} 1.0

Documentation

• I thought about documentation and added the doc-change-required label to this PR if
  updates are required.

Changelog

• I thought about the changelog and included a changelog update if required.

[jflo]

Thanks for the contrib!

[shemnon]

Metrics is the wrong place for this. Long term it will increase the cardinality of the measures and really isn't a metric of operation. This is more appropriate for log output, and is, in fact, already present in log outputs.

[mcdee]

@shemnon logs aren't easily available remotely, and commonly this sort of information leaves the logs relatively quickly as they rotate or are truncated. All beacon nodes provide some form of this information in their metrics, and it has proven useful to be able to obtain information about the deployed version across multiple instances in larger operational environments.

As for the cardinality, we're talking 20-30 per year and this is insignificant compared to the volume of data being gathered elsewhere.

[shemnon]

Its a bad devops practice. What is the measure of the gauge? The real measure is coming through a label instead of the metric itself, the metric should be what is queried, not the labels.

All beacon nodes provide some form of this information in their metrics

Can you provide concrete examples?

[mcdee]

What is the measure of the gauge?

It is the number of instances of the process that are running, with the label being the version. It may not seem to make so much sense when you are considering a single instance, but aggregating this metric across a larger environment provides information on the breakdown of how many instances of each version are active.

Can you provide concrete examples?

Lighthouse:

lighthouse_info{version="Lighthouse/v2.3.1-a9e1586"} 1

Nimbus:

version{version="v22.5.2-f124f2-stateofus",commit="f124f2"} 1.0

Prysm:

prysm_version{buildDate="1655730327",commit="56af079aeaf5544304d289e12b49973485987b29",version="v2.1.3-rc.4"} 1

Teku:

beacon_teku_version{version="22.6.0",} 1.0

[shemnon]

Since this has become an industry standard I'll remove my block.

But I will leave my non-blocking objection that this is an abuse of metrics.

making my objection non-blocking.