func Create()

in cluster/cluster.go [131:255]
111 lines of code
18 McCabe index (conditional complexity)

func Create(
	l log.Logger,
	reg prometheus.Registerer,
	bindAddr string,
	advertiseAddr string,
	knownPeers []string,
	waitIfEmpty bool,
	pushPullInterval time.Duration,
	gossipInterval time.Duration,
	tcpTimeout time.Duration,
	probeTimeout time.Duration,
	probeInterval time.Duration,
	tlsTransportConfig *TLSTransportConfig,
	allowInsecureAdvertise bool,
	label string,
) (*Peer, error) {
	bindHost, bindPortStr, err := net.SplitHostPort(bindAddr)
	if err != nil {
		return nil, fmt.Errorf("invalid listen address: %w", err)
	}
	bindPort, err := strconv.Atoi(bindPortStr)
	if err != nil {
		return nil, fmt.Errorf("address %s: invalid port: %w", bindAddr, err)
	}

	var advertiseHost string
	var advertisePort int
	if advertiseAddr != "" {
		var advertisePortStr string
		advertiseHost, advertisePortStr, err = net.SplitHostPort(advertiseAddr)
		if err != nil {
			return nil, fmt.Errorf("invalid advertise address: %w", err)
		}
		advertisePort, err = strconv.Atoi(advertisePortStr)
		if err != nil {
			return nil, fmt.Errorf("address %s: invalid port: %w", advertiseAddr, err)
		}
	}

	resolvedPeers, err := resolvePeers(context.Background(), knownPeers, advertiseAddr, &net.Resolver{}, waitIfEmpty)
	if err != nil {
		return nil, fmt.Errorf("resolve peers: %w", err)
	}
	level.Debug(l).Log("msg", "resolved peers to following addresses", "peers", strings.Join(resolvedPeers, ","))

	// Initial validation of user-specified advertise address.
	addr, err := calculateAdvertiseAddress(bindHost, advertiseHost, allowInsecureAdvertise)
	if err != nil {
		level.Warn(l).Log("err", "couldn't deduce an advertise address: "+err.Error())
	} else if hasNonlocal(resolvedPeers) && isUnroutable(addr.String()) {
		level.Warn(l).Log("err", "this node advertises itself on an unroutable address", "addr", addr.String())
		level.Warn(l).Log("err", "this node will be unreachable in the cluster")
		level.Warn(l).Log("err", "provide --cluster.advertise-address as a routable IP address or hostname")
	} else if isAny(bindAddr) && advertiseHost == "" {
		// memberlist doesn't advertise properly when the bind address is empty or unspecified.
		level.Info(l).Log("msg", "setting advertise address explicitly", "addr", addr.String(), "port", bindPort)
		advertiseHost = addr.String()
		advertisePort = bindPort
	}

	// TODO(fabxc): generate human-readable but random names?
	name, err := ulid.New(ulid.Now(), rand.New(rand.NewSource(time.Now().UnixNano())))
	if err != nil {
		return nil, err
	}

	p := &Peer{
		states:        map[string]State{},
		stopc:         make(chan struct{}),
		readyc:        make(chan struct{}),
		logger:        l,
		peers:         map[string]peer{},
		resolvedPeers: resolvedPeers,
		knownPeers:    knownPeers,
	}

	p.register(reg, name.String())

	retransmit := len(knownPeers) / 2
	if retransmit < 3 {
		retransmit = 3
	}
	p.delegate = newDelegate(l, reg, p, retransmit)

	cfg := memberlist.DefaultLANConfig()
	cfg.Name = name.String()
	cfg.BindAddr = bindHost
	cfg.BindPort = bindPort
	cfg.Delegate = p.delegate
	cfg.Ping = p.delegate
	cfg.Alive = p.delegate
	cfg.Events = p.delegate
	cfg.GossipInterval = gossipInterval
	cfg.PushPullInterval = pushPullInterval
	cfg.TCPTimeout = tcpTimeout
	cfg.ProbeTimeout = probeTimeout
	cfg.ProbeInterval = probeInterval
	cfg.LogOutput = &logWriter{l: l}
	cfg.GossipNodes = retransmit
	cfg.UDPBufferSize = MaxGossipPacketSize
	cfg.Label = label

	if advertiseHost != "" {
		cfg.AdvertiseAddr = advertiseHost
		cfg.AdvertisePort = advertisePort
		p.setInitialFailed(resolvedPeers, fmt.Sprintf("%s:%d", advertiseHost, advertisePort))
	} else {
		p.setInitialFailed(resolvedPeers, bindAddr)
	}

	if tlsTransportConfig != nil {
		level.Info(l).Log("msg", "using TLS for gossip")
		cfg.Transport, err = NewTLSTransport(context.Background(), l, reg, cfg.BindAddr, cfg.BindPort, tlsTransportConfig)
		if err != nil {
			return nil, fmt.Errorf("tls transport: %w", err)
		}
	}

	ml, err := memberlist.Create(cfg)
	if err != nil {
		return nil, fmt.Errorf("create memberlist: %w", err)
	}
	p.mlist = ml
	return p, nil
}