cluster: add etcd based leader elector and factory

lncfg/cluster.go

@@ -0,0 +1,38 @@
+package lncfg
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/cluster"
+)
+
+// Cluster holds configuration for clustered LND.
+type Cluster struct {
+	LeaderElector string `long:"leader-elector" choice:"etcd" description:"Leader elector to use. Valid values: \"etcd\"."`
+
+	EtcdElectionPrefix string `long:"etcd-election-prefix" description:"Election key prefix when using etcd leader elector."`
+}
+
+// DefaultCluster creates and returns a new default DB config.
+func DefaultCluster() *Cluster {
+	return &Cluster{}
+}
+
+// Validate validates the Cluster config.
+func (c *Cluster) Validate() error {
+	switch c.LeaderElector {
+	case cluster.EtcdLeaderElector:
+		if c.EtcdElectionPrefix == "" {
+			return fmt.Errorf("etcd-election-prefix must be set")
+		}
+
+	default:
+		return fmt.Errorf("unknown leader elector, valid values are: "+
+			"\"%v\"", cluster.EtcdLeaderElector)
+	}
+
+	return nil
+}
+
+// Compile-time constraint to ensure Workers implements the Validator interface.
+var _ Validator = (*Cluster)(nil)