Add a new protocol

Co-authored-by: Gérald Croës <gerald@containo.us>
2019-03-14 09:30:04 +01:00 · 2019-03-14 09:30:04 +01:00 · 4a68d29ce2
commit 4a68d29ce2
parent 0ca2149408
231 changed files with 6895 additions and 4395 deletions
--- a/old/cluster/leadership.go
+++ b/old/cluster/leadership.go
@ -0,0 +1,146 @@
+package cluster
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/cenkalti/backoff"
+	"github.com/containous/mux"
+	"github.com/containous/traefik/log"
+	"github.com/containous/traefik/old/types"
+	"github.com/containous/traefik/safe"
+	"github.com/docker/leadership"
+	"github.com/unrolled/render"
+)
+
+const clusterLeaderKeySuffix = "/leader"
+
+var templatesRenderer = render.New(render.Options{
+	Directory: "nowhere",
+})
+
+// Leadership allows leadership election using a KV store
+type Leadership struct {
+	*safe.Pool
+	*types.Cluster
+	candidate *leadership.Candidate
+	leader    *safe.Safe
+	listeners []LeaderListener
+}
+
+// NewLeadership creates a leadership
+func NewLeadership(ctx context.Context, cluster *types.Cluster) *Leadership {
+	return &Leadership{
+		Pool:      safe.NewPool(ctx),
+		Cluster:   cluster,
+		candidate: leadership.NewCandidate(cluster.Store, cluster.Store.Prefix+clusterLeaderKeySuffix, cluster.Node, 20*time.Second),
+		listeners: []LeaderListener{},
+		leader:    safe.New(false),
+	}
+}
+
+// LeaderListener is called when leadership has changed
+type LeaderListener func(elected bool) error
+
+// Participate tries to be a leader
+func (l *Leadership) Participate(pool *safe.Pool) {
+	pool.GoCtx(func(ctx context.Context) {
+		log.Debugf("Node %s running for election", l.Cluster.Node)
+		defer log.Debugf("Node %s no more running for election", l.Cluster.Node)
+		backOff := backoff.NewExponentialBackOff()
+		operation := func() error {
+			return l.run(ctx, l.candidate)
+		}
+
+		notify := func(err error, time time.Duration) {
+			log.Errorf("Leadership election error %+v, retrying in %s", err, time)
+		}
+		err := backoff.RetryNotify(safe.OperationWithRecover(operation), backOff, notify)
+		if err != nil {
+			log.Errorf("Cannot elect leadership %+v", err)
+		}
+	})
+}
+
+// AddListener adds a leadership listener
+func (l *Leadership) AddListener(listener LeaderListener) {
+	l.listeners = append(l.listeners, listener)
+}
+
+// Resign resigns from being a leader
+func (l *Leadership) Resign() {
+	l.candidate.Resign()
+	log.Infof("Node %s resigned", l.Cluster.Node)
+}
+
+func (l *Leadership) run(ctx context.Context, candidate *leadership.Candidate) error {
+	electedCh, errCh := candidate.RunForElection()
+	for {
+		select {
+		case elected := <-electedCh:
+			l.onElection(elected)
+		case err := <-errCh:
+			return err
+		case <-ctx.Done():
+			l.candidate.Resign()
+			return nil
+		}
+	}
+}
+
+func (l *Leadership) onElection(elected bool) {
+	if elected {
+		log.Infof("Node %s elected leader ♚", l.Cluster.Node)
+		l.leader.Set(true)
+		l.Start()
+	} else {
+		log.Infof("Node %s elected worker ♝", l.Cluster.Node)
+		l.leader.Set(false)
+		l.Stop()
+	}
+	for _, listener := range l.listeners {
+		err := listener(elected)
+		if err != nil {
+			log.Errorf("Error calling Leadership listener: %s", err)
+		}
+	}
+}
+
+type leaderResponse struct {
+	Leader     bool   `json:"leader"`
+	LeaderNode string `json:"leader_node"`
+}
+
+func (l *Leadership) getLeaderHandler(response http.ResponseWriter, request *http.Request) {
+	leaderNode := ""
+	leaderKv, err := l.Cluster.Store.Get(l.Cluster.Store.Prefix+clusterLeaderKeySuffix, nil)
+	if err != nil {
+		log.Error(err)
+	} else {
+		leaderNode = string(leaderKv.Value)
+	}
+	leader := &leaderResponse{Leader: l.IsLeader(), LeaderNode: leaderNode}
+
+	status := http.StatusOK
+	if !leader.Leader {
+		// Set status to be `429`, as this will typically cause load balancers to stop sending requests to the instance without removing them from rotation.
+		status = http.StatusTooManyRequests
+	}
+
+	err = templatesRenderer.JSON(response, status, leader)
+	if err != nil {
+		log.Error(err)
+	}
+}
+
+// IsLeader returns true if current node is leader
+func (l *Leadership) IsLeader() bool {
+	return l.leader.Get().(bool)
+}
+
+// AddRoutes add dashboard routes on a router
+func (l *Leadership) AddRoutes(router *mux.Router) {
+	// Expose cluster leader
+	router.Methods(http.MethodGet).Path("/api/cluster/leader").HandlerFunc(l.getLeaderHandler)
+}