Method reconcileZeroAddresses

dgraph/cmd/zero/raft.go:734–802

reconcileZeroAddresses detects mismatches between the current --my address (or transport-layer peer addresses) and what is stored in MembershipState, then proposes a ConfChangeUpdateNode through Raft to correct them. This ensures that stale addresses baked into the WAL at initial bootstrap are repla

()

// replaced with the current addresses after a restart. Only the leader can
// propose, so this function is a no-op on followers.
func (n *node) reconcileZeroAddresses() {
	if !n.AmLeader() {
		return
	}

	state := n.server.membershipState()
	if state == nil {
		return
	}

	for id, zero := range state.GetZeros() {
		var correctAddr string

		if id == n.Id {
			correctAddr = n.RaftContext.Addr
		} else if peerAddr, ok := n.Peer(id); ok {
			correctAddr = peerAddr
		} else {
			continue
		}

		if correctAddr == zero.GetAddr() {
			continue
		}

		// Validate: ensure no other Zero already claims this address.
		duplicate := false
		for otherId, otherZero := range state.GetZeros() {
			if otherId != id && otherZero.GetAddr() == correctAddr {
				glog.Warningf("Skipping address reconciliation for Zero %#x: "+
					"address %q already used by Zero %#x", id, correctAddr, otherId)
				duplicate = true
				break
			}
		}
		if duplicate {
			continue
		}

		glog.Infof("Zero %#x address mismatch: MembershipState has %q, expected %q. "+
			"Proposing ConfChangeUpdateNode.", id, zero.GetAddr(), correctAddr)

		rc := &pb.RaftContext{
			Id:    id,
			Addr:  correctAddr,
			Group: 0,
		}
		data, err := proto.Marshal(rc)
		if err != nil {
			glog.Errorf("Error marshalling RaftContext for address update: %v", err)
			continue
		}

		cc := raftpb.ConfChange{
			Type:    raftpb.ConfChangeUpdateNode,
			NodeID:  id,
			Context: data,
		}