🎉 Initial Commit

pkg/shared/registrar/mod.go

@@ -0,0 +1,84 @@
+// Package registrar is for the service discovery system
+package registrar
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	clientv3 "go.etcd.io/etcd/client/v3"
+)
+
+type ServiceRegistrar struct {
+	client  *clientv3.Client
+	leaseID clientv3.LeaseID
+	ttl     int64
+	key     string
+	cancel  context.CancelFunc
+}
+
+// NewServiceRegistrar creates a registrar with the given etcd client
+func NewServiceRegistrar(endpoints []string) (*ServiceRegistrar, error) {
+	cfg := clientv3.Config{
+		Endpoints:   endpoints,
+		DialTimeout: 5 * time.Second,
+	}
+
+	cli, err := clientv3.New(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ServiceRegistrar{client: cli}, nil
+}
+
+// Register service with etcd using TTL lease
+func (r *ServiceRegistrar) Register(serviceName string, servicePart string, instanceID string, host string, port int, ttlSeconds int64) error {
+	r.ttl = ttlSeconds
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+
+	r.key = fmt.Sprintf("/services/%s/%s/%s", serviceName, servicePart, instanceID)
+
+	// Create lease
+	leaseResp, err := r.client.Grant(ctx, r.ttl)
+	if err != nil {
+		return err
+	}
+
+	r.leaseID = leaseResp.ID
+
+	// Put key with lease
+	_, err = r.client.Put(ctx, r.key, fmt.Sprintf("%s:%d", host, port), clientv3.WithLease(r.leaseID))
+	if err != nil {
+		return err
+	}
+
+	// Keep alive context
+	kaCtx, kaCancel := context.WithCancel(context.Background())
+	r.cancel = kaCancel
+
+	// Keep lease alive
+	go func() {
+		ch, err := r.client.KeepAlive(kaCtx, r.leaseID)
+		if err != nil {
+			fmt.Printf("KeepAlive error: %v\n", err)
+			return
+		}
+		for range ch {
+			// optionally inspect TTL updates here
+		}
+	}()
+
+	return nil
+}
+
+// Deregister removes the registered key and stops keep-alive
+func (r *ServiceRegistrar) Deregister() error {
+	if r.cancel != nil {
+		r.cancel()
+	}
+
+	_, err := r.client.Delete(context.Background(), r.key)
+	return err
+}