Proposal: hierarchical metric tag maps in standalone.yml

[liaodn]

Background

Currently StandaloneStarter only adds a single env common tag to the global registry. In multi-cluster deployments, it would be nice to have more flexible tagging at different levels.

Rough Idea

Introduce a metricsTags map at different levels, something like:

Process-level — global tags for all metrics in the process:

metricsTags:
  region: gz
  deployment: canary

Cluster-level — tags scoped to a specific host-cluster:

agent:
  hostcluster:
    metricsTags:
      cluster: regional-a
      cluster_scope: regional

Subservice propagation — cluster-level tags could also propagate to base-kv, base-rpc, etc.

Thoughts on Precedence

For the same key: process-level < cluster-level < metric-local tags. But this is open for discussion.

Possible Phases

This is quite a bit of scope, so it might make sense to phase it:

1. Process-level metricsTags
2. Cluster-level metricsTags under agent.hostcluster
3. Propagation to base-cluster subservices

Would love to hear thoughts on whether this direction makes sense, and if the naming / precedence / phasing look reasonable.