Files
MusicServer/internal/metrics/http.go
SansanandClaude Opus 5.5 f79f51ea4c
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Expose Prometheus metrics on a separate port
Metrics are served on METRICS_PORT (default 2112, "off" to disable), never on
the public port. Besides the Go runtime and process metrics this adds:

- http_requests_total and http_request_duration_seconds per route pattern,
  from an Echo middleware.
- musicserver_songs_requested_total and musicserver_songs_played_total by
  pick mode (random, low, classic). The mode is now stored with each queued
  song (migration 000006, not released yet).
- Library size, sync duration, last successful sync, broken songs from the
  last full sync, and the database connection pool.

Refs #35, #36, #37

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-11 21:57:58 +02:00

50 lines
1.6 KiB
Go

package metrics
import (
"strconv"
"time"
"github.com/labstack/echo/v5"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
var (
httpRequests = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "http_requests_total",
Help: "HTTP requests by method, route and status code.",
}, []string{"method", "route", "code"})
httpDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
Name: "http_request_duration_seconds",
Help: "HTTP request latency by method and route. Song downloads include the transfer.",
// Up to 30 s, since songs can take long to send to slow clients.
Buckets: []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10, 30},
}, []string{"method", "route"})
)
// unmatchedRoute labels requests that matched no route, so raw URLs never become labels.
const unmatchedRoute = "unmatched"
// Middleware records the count and latency of requests per route. The route label is the
// registered pattern, like /api/v1/songs/:uuid, never the URL with its IDs and query.
// Register it outside Recover, so requests that panic are counted as 500.
func Middleware() echo.MiddlewareFunc {
return func(next echo.HandlerFunc) echo.HandlerFunc {
return func(c *echo.Context) error {
start := time.Now()
err := next(c)
route := c.Path()
if route == "" {
route = unmatchedRoute
}
_, status := echo.ResolveResponseStatus(c.Response(), err)
method := c.Request().Method
httpRequests.WithLabelValues(method, route, strconv.Itoa(status)).Inc()
httpDuration.WithLabelValues(method, route).Observe(time.Since(start).Seconds())
return err
}
}
}