observability-prom

observability-prom

Reference adapter bridging theauth.Metrics to github.com/prometheus/client_golang/prometheus.

Use

import (
    "net/http"

    "github.com/glincker/theauth-go"
    prombridge "github.com/glincker/theauth-go/examples/observability-prom"
    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

reg := prometheus.NewRegistry()
metrics := prombridge.New(reg)
hooks := &theauth.Hooks{Metrics: metrics}

auth, _ := theauth.New(theauth.Config{
    Storage:       store,
    BaseURL:       "https://example.com",
    Observability: hooks,
})

http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))

Cardinality discipline

The library only emits low-cardinality metric labels (grant_type, status, rule, kind). High-cardinality identifiers (client_id, user_id, etc.) live on spans, never on metric labels. The bridge memoizes by (name, label-name-set) so accidental label-set drift on the same metric name is caught at registration time.

Histogram buckets

The library passes theauth.LatencyBuckets for every _latency_seconds metric. The bridge uses whatever buckets the library supplies on the FIRST Histogram(name, ...) call; subsequent calls re-use the same vec regardless of supplied buckets (a Prometheus constraint, not a bridge choice).