TUN-3593: /ready endpoint for k8s readiness. Move tunnel events out of UI package, into connection package.

metrics/readiness.go

@@ -0,0 +1,80 @@
+package metrics
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync"
+
+	conn "github.com/cloudflare/cloudflared/connection"
+	"github.com/cloudflare/cloudflared/logger"
+)
+
+// ReadyServer serves HTTP 200 if the tunnel can serve traffic. Intended for k8s readiness checks.
+type ReadyServer struct {
+	sync.RWMutex
+	isConnected map[int]bool
+	log         logger.Service
+}
+
+// NewReadyServer initializes a ReadyServer and starts listening for dis/connection events.
+func NewReadyServer(connectionEvents <-chan conn.Event, log logger.Service) *ReadyServer {
+	rs := ReadyServer{
+		isConnected: make(map[int]bool, 0),
+		log:         log,
+	}
+	go func() {
+		for c := range connectionEvents {
+			switch c.EventType {
+			case conn.Connected:
+				rs.Lock()
+				rs.isConnected[int(c.Index)] = true
+				rs.Unlock()
+			case conn.Disconnected, conn.Reconnecting, conn.RegisteringTunnel:
+				rs.Lock()
+				rs.isConnected[int(c.Index)] = false
+				rs.Unlock()
+			case conn.SetURL:
+				continue
+			default:
+				rs.log.Errorf("Unknown connection event case %v", c)
+			}
+		}
+	}()
+	return &rs
+}
+
+type body struct {
+	Status           int `json:"status"`
+	ReadyConnections int `json:"readyConnections"`
+}
+
+// ServeHTTP responds with HTTP 200 if the tunnel is connected to the edge.
+func (rs *ReadyServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	statusCode, readyConnections := rs.makeResponse()
+	w.WriteHeader(statusCode)
+	body := body{
+		Status:           statusCode,
+		ReadyConnections: readyConnections,
+	}
+	msg, err := json.Marshal(body)
+	if err != nil {
+		fmt.Fprintf(w, `{"error": "%s"}`, err)
+	}
+	w.Write(msg)
+}
+
+// This is the bulk of the logic for ServeHTTP, broken into its own pure function
+// to make unit testing easy.
+func (rs *ReadyServer) makeResponse() (statusCode, readyConnections int) {
+	statusCode = http.StatusServiceUnavailable
+	rs.RLock()
+	defer rs.RUnlock()
+	for _, connected := range rs.isConnected {
+		if connected {
+			statusCode = http.StatusOK
+			readyConnections++
+		}
+	}
+	return statusCode, readyConnections
+}