feat: try to reconnect to ldap server if heartbeat fails

internal/ldap/ldap.go

@@ -1,11 +1,13 @@
 package ldap
 
 import (
+	"context"
 	"crypto/tls"
 	"fmt"
 	"time"
 	"tinyauth/internal/types"
 
+	"github.com/cenkalti/backoff/v5"
 	ldapgo "github.com/go-ldap/ldap/v3"
 	"github.com/rs/zerolog/log"
 )
@@ -30,6 +32,11 @@ func NewLDAP(config types.LdapConfig) (*LDAP, error) {
 			err := ldap.heartbeat()
 			if err != nil {
 				log.Error().Err(err).Msg("LDAP connection heartbeat failed")
+				if reconnectErr := ldap.reconnect(); reconnectErr != nil {
+					log.Error().Err(reconnectErr).Msg("Failed to reconnect to LDAP server")
+					continue
+				}
+				log.Info().Msg("Successfully reconnected to LDAP server")
 			}
 		}
 	}()
@@ -38,6 +45,7 @@ func NewLDAP(config types.LdapConfig) (*LDAP, error) {
 }
 
 func (l *LDAP) connect() (*ldapgo.Conn, error) {
+	log.Debug().Msg("Connecting to LDAP server")
 	conn, err := ldapgo.DialURL(l.Config.Address, ldapgo.DialWithTLSConfig(&tls.Config{
 		InsecureSkipVerify: l.Config.Insecure,
 		MinVersion:         tls.VersionTLS12,
@@ -46,6 +54,7 @@ func (l *LDAP) connect() (*ldapgo.Conn, error) {
 		return nil, err
 	}
 
+	log.Debug().Msg("Binding to LDAP server")
 	err = conn.Bind(l.Config.BindDN, l.Config.BindPassword)
 	if err != nil {
 		return nil, err
@@ -109,3 +118,29 @@ func (l *LDAP) heartbeat() error {
 	// No error means the connection is alive
 	return nil
 }
+
+func (l *LDAP) reconnect() error {
+	log.Info().Msg("Reconnecting to LDAP server")
+
+	exp := backoff.NewExponentialBackOff()
+	exp.InitialInterval = 500 * time.Millisecond
+	exp.RandomizationFactor = 0.1
+	exp.Multiplier = 1.5
+	exp.Reset()
+
+	operation := func() (*ldapgo.Conn, error) {
+		_, err := l.connect()
+		if err != nil {
+			return nil, nil
+		}
+		return nil, nil
+	}
+
+	_, err := backoff.Retry(context.TODO(), operation, backoff.WithBackOff(exp), backoff.WithMaxTries(3))
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}