Method configureZoneAwareRouting

kv/memberlist/memberlist_client.go:565–607

configureZoneAwareRouting configures zone-aware routing for memberlist.

(mlCfg *memberlist.Config)

// configureZoneAwareRouting configures zone-aware routing for memberlist.
func (m *KV) configureZoneAwareRouting(mlCfg *memberlist.Config) error {
	// Parse the role from the config string.
	var role NodeRole
	switch m.cfg.ZoneAwareRouting.Role {
	case NodeRoleMember.String():
		role = NodeRoleMember
	case NodeRoleBridge.String():
		role = NodeRoleBridge
	default:
		return fmt.Errorf("invalid zone-aware routing role: %s (valid values: %s, %s)", m.cfg.ZoneAwareRouting.Role, NodeRoleMember.String(), NodeRoleBridge.String())
	}

	// Encode the local node metadata.
	localMeta, err := EncodeNodeMetadata(role, m.cfg.ZoneAwareRouting.Zone)
	if err != nil {
		return fmt.Errorf("failed to encode node metadata: %w", err)
	}

	// Store the encoded metadata so NodeMeta() can return it.
	m.nodeMeta = localMeta

	// Set up the node selection delegate.
	mlCfg.NodeSelection = newZoneAwareNodeSelectionDelegate(role, m.cfg.ZoneAwareRouting.Zone, m.logger, m.registerer)

	// The bridge always prefer another bridge as first node. If the bridge only push/pull to 1 node per interval, then
	// it will only communicate to bridges, potentially leading to network partitioning if the gossiping is not
	// working to propagate changes. To reduce the likelihood of network partitioning when gossiping is not
	// working and periodic push/pull is enabled, we configure the bridge to push/pull to 2 nodes per interval
	// (the first node is a bridge, and the second node is selected randomly).
	if role == NodeRoleBridge {
		mlCfg.PushPullNodes = 2
	} else {
		mlCfg.PushPullNodes = 1
	}

	level.Info(m.logger).Log(
		"msg", "zone-aware routing enabled",
		"zone", m.cfg.ZoneAwareRouting.Zone,
		"role", role.String(),
	)

	return nil
}

func (m *KV) starting(ctx context.Context) error {
	mlCfg, err := m.buildMemberlistConfig()