Add function to analyse used labels, and not just used metrics.

[tomwilkie]

This is a WIP PR which analyses the usage of labels, and not just metric names. The idea is eventually we'll be able to identify labels we can drop / aggregate way.

Lots of this exists already (great work @gouthamve) but AFAICT only analyses metric names? I plan on just working through this pipeline and updating everything to consider labels too.

 1.Extract Queries     2.Line-delimited  3.Extract Labels
                         PromQL queries
┌────────────────────┐
│  Prometheus Logs   ├─────────┐
└────────────────────┘         │
                               │
┌────────────────────┐         │         ┌───────────────┐
│  Prometheus Rules  ├─────────┼────────►│ Query Analyse │
└────────────────────┘         │         └───────┬───────┘
                               │                 │
┌────────────────────┐         │                 │
│ Grafana Dashboards ├─────────┘                 │
└────────────────────┘                           │
                                                 │
                                                 │
                                                 │
 4.Extract Series Labels                         │   5. Find unused labels
                                                 ▼
┌────────────────────┐                   ┌───────────────┐
│    Active Series   ├──────────────────►│   Label Diff  │
└────────────────────┘                   └───────┬───────┘
                                                 │
                                                 │
                                                 │
                                                 │
                                                 │
 6.Extract Series Counts                         │   7. Rank unused labels
                                                 ▼      to find best
┌────────────────────┐                   ┌───────────────┐
│    Active Series   ├──────────────────►│  Rank Unused  │
└────────────────────┘                   └───────┬───────┘
                                                 │
                                                 │
                                                 ▼
                                         ┌───────────────┐
                                         │  Aggregation  │
                                         │     Rules     │
                                         └───────────────┘

Signed-off-by: Tom Wilkie tom.wilkie@gmail.com

[replay]

why not just use a temporary map for the used labels?

[tomwilkie]

No particular reason, I guess I was expecting this list to be short and this to be cheaper than all the allocs associated with maps.

[CLAassistant]

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