reconnect jitter configurable (#467)

* reconnect jitter configurable * updated docs: reconnect jitter configurable * Update pkg/common/nats/conn.go Co-authored-by: Dan <5727701+dan-j@users.noreply.github.com> --------- Co-authored-by: Dan <5727701+dan-j@users.noreply.github.com>
knative-extensions · Jan 11, 2024 · 44752ad · 44752ad
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diff --git a/docs/jetstream.md b/docs/jetstream.md
@@ -106,9 +106,11 @@ data:
             secret:
                 name: ""                # a secret containing a `ca.crt` entry.
         connOpts:
-          retryOnFailedConnect: true    # should it reconnect on failed connection
-          maxReconnects: 50             # max reconnect attempts
-          reconnectWait: 2000           # delay between reconnect attempts
+          retryOnFailedConnect: true           # should it reconnect on failed connection
+          maxReconnects: 50                    # max reconnect attempts
+          reconnectWait: 2000                  # delay between reconnect attempts
+          reconnectJitterMilliseconds: 100     # upper bound of a random delay added ReconnectWait
+          reconnectJitterTLSMilliseconds: 1000 # upper bound of a random delay added ReconnectWait
 ```
 
 ## JetStream integration

diff --git a/examples/config-nats.yaml b/examples/config-nats.yaml
@@ -10,4 +10,5 @@ data:
       retryOnFailedConnect: true
       maxReconnects: 5
       reconnectWaitMilliseconds: 2000
-
+      reconnectJitterMilliseconds: 100
+      reconnectJitterTLSMilliseconds: 1000
diff --git a/pkg/common/config/eventingnatsconfig.go b/pkg/common/config/eventingnatsconfig.go
@@ -71,4 +71,8 @@ type ConnOpts struct {
 	RetryOnFailedConnect bool `json:"retryOnFailedConnect,omitempty"`
 	// ReconnectWaitMilliseconds time between reconnects in milliseconds
 	ReconnectWaitMilliseconds int `json:"reconnectWaitMilliseconds,omitempty"`
+	// ReconnectJitterMilliseconds Option to set the upper bound of a random delay added ReconnectWait
+	ReconnectJitterMilliseconds int `json:"reconnectJitterMilliseconds,omitempty"`
+	// ReconnectJitterTLSMilliseconds Option to set the upper bound of a random delay added ReconnectWait
+	ReconnectJitterTLSMilliseconds int `json:"reconnectJitterTLSMilliseconds,omitempty"`
 }
diff --git a/pkg/common/nats/conn.go b/pkg/common/nats/conn.go
@@ -38,6 +38,11 @@ import (
 	"knative.dev/eventing-natss/pkg/common/constants"
 )
 
+const (
+	defaultReconnectJitter    = time.Duration(100) * time.Millisecond
+	defaultReconnectJitterTLS = time.Duration(1000) * time.Millisecond
+)
+
 var (
 	ErrBadCredentialFileOption = errors.New("bad auth.credentialFile option")
 	ErrBadMTLSOption           = errors.New("bad auth.tls option")
@@ -82,6 +87,9 @@ func NewNatsConn(ctx context.Context, config commonconfig.EventingNatsConfig) (*
 	// reconnection options
 	if config.ConnOpts != nil && config.ConnOpts.RetryOnFailedConnect {
 		reconnectWait := time.Duration(config.ConnOpts.ReconnectWaitMilliseconds) * time.Millisecond
+		reconnectJitter := defaultJitterIfEmpty(config.ConnOpts.ReconnectJitterMilliseconds, defaultReconnectJitter)
+		reconnectJitterTLS := defaultJitterIfEmpty(config.ConnOpts.ReconnectJitterTLSMilliseconds, defaultReconnectJitterTLS)
+
 		logger.Infof("Configuring retries: %#v", config.ConnOpts)
 		opts = append(opts, nats.RetryOnFailedConnect(config.ConnOpts.RetryOnFailedConnect))
 		opts = append(opts, nats.ReconnectWait(reconnectWait))
@@ -93,7 +101,7 @@ func NewNatsConn(ctx context.Context, config commonconfig.EventingNatsConfig) (*
 			logger.Debugf("Reconnect attempts left: %d", config.ConnOpts.MaxReconnects-attempts)
 			return reconnectWait
 		}))
-		opts = append(opts, nats.ReconnectJitter(1000, time.Millisecond))
+		opts = append(opts, nats.ReconnectJitter(reconnectJitter, reconnectJitterTLS))
 		opts = append(opts, nats.DisconnectErrHandler(func(conn *nats.Conn, err error) {
 			logger.Warnf("Disconnected from JSM: err=%v", err)
 			logger.Warnf("Disconnected from JSM: will attempt reconnects for %d", config.ConnOpts.MaxReconnects)
@@ -108,6 +116,13 @@ func NewNatsConn(ctx context.Context, config commonconfig.EventingNatsConfig) (*
 	return nats.Connect(url, opts...)
 }
 
+func defaultJitterIfEmpty(jitter int, defaultValue time.Duration) time.Duration {
+	if jitter == 0 {
+		return defaultValue
+	}
+	return time.Duration(jitter) * time.Millisecond
+}
+
 func buildAuthOption(ctx context.Context, config commonconfig.ENConfigAuth, secrets clientsetcorev1.SecretInterface) ([]nats.Option, error) {
 	opts := make([]nats.Option, 0, 2)
 	if config.CredentialFile != nil {