pkg/prometheus: init

pkg/prometheus/server.go

@@ -0,0 +1,50 @@
+// Package prometheus implements a standalone HTTP server for serving a
+// Prometheus metrics endpoint.
+package prometheus
+
+import (
+	"context"
+	"net/http"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Server represents a standalone HTTP server for serving a Prometheus metrics
+// endpoint.
+type Server struct {
+	srv *http.Server
+}
+
+// Stop shuts down the server.
+func (s *Server) Stop() <-chan error {
+	c := make(chan error)
+	go func() {
+		if err := s.srv.Shutdown(context.Background()); err != nil {
+			c <- err
+		} else {
+			close(c)
+		}
+	}()
+
+	return c
+}
+
+// NewServer creates a new instance of a Prometheus server that asynchronously
+// serves requests.
+func NewServer(addr string) *Server {
+	s := &Server{
+		srv: &http.Server{
+			Addr:    addr,
+			Handler: prometheus.Handler(),
+		},
+	}
+
+	go func() {
+		if err := s.srv.ListenAndServe(); err != http.ErrServerClosed {
+			log.Fatal("failed while serving prometheus: " + err.Error())
+		}
+	}()
+
+	return s
+}