* Upgrade to using hashicorp/go-metrics@v0.5.4
This also requires bumping the dependencies for:
* memberlist
* serf
* raft
* raft-boltdb
* (and indirectly hashicorp/mdns due to the memberlist or serf update)
Unlike some other HashiCorp products, Nomads root module is currently expected to be consumed by others. This means that it needs to be treated more like our libraries and upgrade to hashicorp/go-metrics by utilizing its compat packages. This allows those importing the root module to control the metrics module used via build tags.
The Nomad client can now optionally emit telemetry data from the
prerun and prestart hooks. This allows operators to monitor and
alert on failures and time taken to complete.
The new datapoints are:
- nomad.client.alloc_hook.prerun.success (counter)
- nomad.client.alloc_hook.prerun.failed (counter)
- nomad.client.alloc_hook.prerun.elapsed (sample)
- nomad.client.task_hook.prestart.success (counter)
- nomad.client.task_hook.prestart.failed (counter)
- nomad.client.task_hook.prestart.elapsed (sample)
The hook execution time is useful to Nomad engineering and will
help optimize code where possible and understand job specification
impacts on hook performance.
Currently only the PreRun and PreStart hooks have telemetry
enabled, so we limit the number of new metrics being produced.
