Kyle Isom
ffc31f7d55
Instrument mc-proxy with prometheus/client_golang. New internal/metrics/ package defines counters, gauges, and histograms for connection totals, active connections, firewall blocks by reason, backend dial latency, bytes transferred, L7 HTTP status codes, and L7 policy blocks. Optional [metrics] config section starts a scrape endpoint. Firewall gains BlockedWithReason() to report block cause. L7 handler wraps ResponseWriter to record status codes per hostname. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
96 lines
2.9 KiB
Go
96 lines
2.9 KiB
Go
// Package metrics defines Prometheus metrics for mc-proxy and provides
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// an HTTP server for the /metrics endpoint.
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package metrics
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import (
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"context"
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"errors"
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"net"
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"net/http"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promauto"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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var (
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// ConnectionsTotal counts connections accepted per listener and mode.
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ConnectionsTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Namespace: "mcproxy",
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Name: "connections_total",
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Help: "Total connections accepted.",
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}, []string{"listener", "mode"})
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// ConnectionsActive tracks currently active connections per listener.
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ConnectionsActive = promauto.NewGaugeVec(prometheus.GaugeOpts{
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Namespace: "mcproxy",
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Name: "connections_active",
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Help: "Currently active connections.",
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}, []string{"listener"})
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// FirewallBlockedTotal counts firewall blocks by reason.
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FirewallBlockedTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Namespace: "mcproxy",
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Name: "firewall_blocked_total",
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Help: "Total connections blocked by the firewall.",
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}, []string{"reason"})
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// BackendDialDuration observes backend dial latency in seconds.
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BackendDialDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
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Namespace: "mcproxy",
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Name: "backend_dial_duration_seconds",
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Help: "Backend dial latency in seconds.",
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Buckets: []float64{0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5},
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}, []string{"backend"})
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// TransferredBytesTotal counts bytes transferred by direction and hostname.
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TransferredBytesTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Namespace: "mcproxy",
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Name: "transferred_bytes_total",
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Help: "Total bytes transferred.",
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}, []string{"direction", "hostname"})
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// L7ResponsesTotal counts L7 HTTP responses by hostname and status code.
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L7ResponsesTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Namespace: "mcproxy",
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Name: "l7_responses_total",
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Help: "Total L7 HTTP responses.",
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}, []string{"hostname", "code"})
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// L7PolicyBlocksTotal counts L7 policy blocks by hostname and policy type.
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L7PolicyBlocksTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Namespace: "mcproxy",
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Name: "l7_policy_blocks_total",
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Help: "Total L7 policy blocks.",
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}, []string{"hostname", "policy_type"})
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)
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// ListenAndServe starts a Prometheus metrics HTTP server. It blocks until
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// ctx is cancelled, then shuts down gracefully.
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func ListenAndServe(ctx context.Context, addr, path string) error {
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if path == "" {
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path = "/metrics"
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}
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mux := http.NewServeMux()
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mux.Handle(path, promhttp.Handler())
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ln, err := net.Listen("tcp", addr)
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if err != nil {
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return err
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}
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srv := &http.Server{Handler: mux}
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go func() {
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<-ctx.Done()
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_ = srv.Close()
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}()
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err = srv.Serve(ln)
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if errors.Is(err, http.ErrServerClosed) {
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return nil
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}
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return err
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}
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