feat: introduce cluster agent

pkg/cluster/agent.go

@@ -0,0 +1,55 @@
+package cluster
+
+import (
+	"log"
+
+	"github.com/0x1d/rcond/pkg/config"
+	"github.com/hashicorp/serf/serf"
+)
+
+type Agent struct {
+	Serf *serf.Serf
+}
+
+func NewAgent(clusterConfig *config.ClusterConfig) (*Agent, error) {
+	config := serf.DefaultConfig()
+	config.NodeName = clusterConfig.NodeName
+	config.ProtocolVersion = serf.ProtocolVersionMax
+	config.MemberlistConfig.SecretKey = []byte(clusterConfig.SecretKey)
+	config.MemberlistConfig.AdvertiseAddr = clusterConfig.AdvertiseAddr
+	config.MemberlistConfig.AdvertisePort = clusterConfig.AdvertisePort
+	config.MemberlistConfig.BindAddr = clusterConfig.BindAddr
+	config.MemberlistConfig.BindPort = clusterConfig.BindPort
+
+	serf, err := serf.Create(config)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Agent{Serf: serf}, nil
+}
+
+func (a *Agent) Members() ([]serf.Member, error) {
+	log.Printf("Getting members of the cluster")
+	return a.Serf.Members(), nil
+}
+
+func (a *Agent) Join(addrs []string, ignoreOld bool) (int, error) {
+	log.Printf("Joining nodes in the cluster: %v", addrs)
+	n, err := a.Serf.Join(addrs, ignoreOld)
+	if err != nil {
+		log.Printf("Failed to join nodes in the cluster: %v", err)
+		return 0, err
+	}
+	log.Printf("Joined %d nodes in the cluster", n)
+	return n, nil
+}
+
+func (a *Agent) Leave() error {
+	return a.Serf.Leave()
+}
+
+func (a *Agent) Shutdown() error {
+	log.Printf("Shutting down cluster agent")
+	return a.Serf.Shutdown()
+}