Changeset 707 in code for trunk/cmd/soju/main.go

Timestamp:

Nov 17, 2021, 2:58:18 PM (4 years ago)

Author:

contact

Message:

Add basic Prometheus metrics exporter

This only exports the default metrics for now.

References: ​https://todo.sr.ht/~emersion/soju/142

File:

• trunk/cmd/soju/main.go (modified) (2 diffs)

trunk/cmd/soju/main.go

@@ -19 +19 @@
 
         "github.com/pires/go-proxyproto"
+        "github.com/prometheus/client_golang/prometheus"
+        "github.com/prometheus/client_golang/prometheus/promhttp"
 
         "git.sr.ht/~emersion/soju"
@@ -255 +257 @@
                                 }
                         }()
+                case "http+prometheus":
+                        if srv.MetricsRegistry == nil {
+                                srv.MetricsRegistry = prometheus.DefaultRegisterer
+                        }
+
+                        // Only allow localhost as listening host for security reasons.
+                        // Users can always explicitly setup reverse proxies if desirable.
+                        hostname, _, err := net.SplitHostPort(u.Host)
+                        if err != nil {
+                                log.Fatalf("invalid host in URI %q: %v", listen, err)
+                        } else if hostname != "localhost" {
+                                log.Fatalf("Prometheus listening host must be localhost")
+                        }
+
+                        metricsHandler := promhttp.HandlerFor(prometheus.DefaultGatherer, promhttp.HandlerOpts{
+                                MaxRequestsInFlight: 10,
+                                Timeout:             10 * time.Second,
+                                EnableOpenMetrics:   true,
+                        })
+                        metricsHandler = promhttp.InstrumentMetricHandler(prometheus.DefaultRegisterer, metricsHandler)
+
+                        httpSrv := http.Server{
+                                Addr:    u.Host,
+                                Handler: metricsHandler,
+                        }
+                        go func() {
+                                if err := httpSrv.ListenAndServe(); err != nil {
+                                        log.Fatalf("serving %q: %v", listen, err)
+                                }
+                        }()
                 default:
                         log.Fatalf("failed to listen on %q: unsupported scheme", listen)