First commit

core/setup/prometheus.go

@@ -0,0 +1,70 @@
+package setup
+
+import (
+	"sync"
+
+	"github.com/miekg/coredns/middleware"
+	prom "github.com/miekg/coredns/middleware/prometheus"
+)
+
+const (
+	path = "/metrics"
+	addr = "localhost:9153"
+)
+
+var once sync.Once
+
+func Prometheus(c *Controller) (middleware.Middleware, error) {
+	metrics, err := parsePrometheus(c)
+	if err != nil {
+		return nil, err
+	}
+	if metrics.Addr == "" {
+		metrics.Addr = addr
+	}
+	once.Do(func() {
+		c.Startup = append(c.Startup, metrics.Start)
+	})
+
+	return func(next middleware.Handler) middleware.Handler {
+		metrics.Next = next
+		return metrics
+	}, nil
+}
+
+func parsePrometheus(c *Controller) (*prom.Metrics, error) {
+	var (
+		metrics *prom.Metrics
+		err     error
+	)
+
+	for c.Next() {
+		if metrics != nil {
+			return nil, c.Err("prometheus: can only have one metrics module per server")
+		}
+		metrics = &prom.Metrics{ZoneNames: c.ServerBlockHosts}
+		args := c.RemainingArgs()
+
+		switch len(args) {
+		case 0:
+		case 1:
+			metrics.Addr = args[0]
+		default:
+			return nil, c.ArgErr()
+		}
+		for c.NextBlock() {
+			switch c.Val() {
+			case "address":
+				args = c.RemainingArgs()
+				if len(args) != 1 {
+					return nil, c.ArgErr()
+				}
+				metrics.Addr = args[0]
+			default:
+				return nil, c.Errf("prometheus: unknown item: %s", c.Val())
+			}
+
+		}
+	}
+	return metrics, err
+}