Show state information for targets when requesting a list of register…

…ed targets

datatypes/MirrorTargets.go

@@ -22,6 +22,12 @@ type MirrorSettings struct {
 	RetryAfter               time.Duration
 }
 
+type Target struct {
+	Name         string
+	FailingSince time.Time
+	State        string
+}
+
 type targetState struct {
 	sync.Mutex
 	firstFailure             time.Time
@@ -66,6 +72,31 @@ func (mt *MirrorTargets) ForEach(f func(string, *gobreaker.CircuitBreaker)) {
 	}
 }
 
+func (mt *MirrorTargets) ListTargets() []Target {
+	targets := make([]Target, len(mt.targets)-1)
+
+	for url, target := range mt.targets {
+		var state string
+		switch target.circuitBreaker.State() {
+		case gobreaker.StateOpen:
+			state = "failing"
+		case gobreaker.StateHalfOpen:
+			state = "retrying"
+		case gobreaker.StateClosed:
+			state = "alive"
+		default:
+			state = "unknown"
+		}
+
+		targets = append(targets, Target{
+			Name:         url,
+			FailingSince: target.firstFailure,
+			State:        state,
+		})
+	}
+	return targets
+}
+
 func (ts *targetState) onBreakerChange(name string, from gobreaker.State, to gobreaker.State) {
 	if from == gobreaker.StateClosed && to == gobreaker.StateOpen {
 		ts.Lock()

main.go

@@ -155,9 +155,13 @@ func mirrorTo(targetURL string, req *http.Request, body []byte, breaker *gobreak
 
 func mirrorsHandler(res http.ResponseWriter, req *http.Request) {
 	if req.Method == http.MethodGet {
-		targets.ForEach(func(target string, breaker *gobreaker.CircuitBreaker) {
-			fmt.Fprintln(res, target)
-		})
+		for _, target := range targets.ListTargets() {
+			if target.State == "alive" {
+				fmt.Fprintf(res, "%s: %s\n", target.Name, target.State)
+			} else {
+				fmt.Fprintf(res, "%s: %s (since: %s)\n", target.Name, target.State, target.FailingSince.UTC().Format(time.RFC3339))
+			}
+		}
 		return
 	}