Separate persistent config struct from LoadBalancer and make fields private

pkg/agent/loadbalancer/config.go

@@ -7,8 +7,18 @@ import (
 	"github.com/k3s-io/k3s/pkg/agent/util"
 )
 
+// lbConfig stores loadbalancer state that should be persisted across restarts.
+type lbConfig struct {
+	ServerURL       string   `json:"ServerURL"`
+	ServerAddresses []string `json:"ServerAddresses"`
+}
+
 func (lb *LoadBalancer) writeConfig() error {
-	configOut, err := json.MarshalIndent(lb, "", "  ")
+	config := &lbConfig{
+		ServerURL:       lb.serverURL,
+		ServerAddresses: lb.serverAddresses,
+	}
+	configOut, err := json.MarshalIndent(config, "", "  ")
 	if err != nil {
 		return err
 	}
@@ -18,9 +28,9 @@ func (lb *LoadBalancer) writeConfig() error {
 func (lb *LoadBalancer) updateConfig() error {
 	writeConfig := true
 	if configBytes, err := os.ReadFile(lb.configFile); err == nil {
-		config := &LoadBalancer{}
+		config := &lbConfig{}
 		if err := json.Unmarshal(configBytes, config); err == nil {
-			if config.ServerURL == lb.ServerURL {
+			if config.ServerURL == lb.serverURL {
 				writeConfig = false
 				lb.setServers(config.ServerAddresses)
 			}

pkg/agent/loadbalancer/loadbalancer.go

@@ -45,13 +45,12 @@ type LoadBalancer struct {
 	localAddress         string
 	localServerURL       string
 	defaultServerAddress string
-	ServerURL            string
-	ServerAddresses      []string
+	serverURL            string
+	serverAddresses      []string
 	randomServers        []string
 	servers              map[string]*server
 	currentServerAddress string
 	nextServerIndex      int
-	Listener             net.Listener
 }
 
 const RandomPort = 0
@@ -105,7 +104,7 @@ func New(ctx context.Context, dataDir, serviceName, serverURL string, lbServerPo
 		localServerURL:       localServerURL,
 		defaultServerAddress: defaultServerAddress,
 		servers:              make(map[string]*server),
-		ServerURL:            serverURL,
+		serverURL:            serverURL,
 	}
 
 	lb.setServers([]string{lb.defaultServerAddress})
@@ -127,7 +126,7 @@ func New(ctx context.Context, dataDir, serviceName, serverURL string, lbServerPo
 	if err := lb.proxy.Start(); err != nil {
 		return nil, err
 	}
-	logrus.Infof("Running load balancer %s %s -> %v [default: %s]", serviceName, lb.localAddress, lb.ServerAddresses, lb.defaultServerAddress)
+	logrus.Infof("Running load balancer %s %s -> %v [default: %s]", serviceName, lb.localAddress, lb.serverAddresses, lb.defaultServerAddress)
 
 	go lb.runHealthChecks(ctx)
 
@@ -141,7 +140,7 @@ func (lb *LoadBalancer) Update(serverAddresses []string) {
 	if !lb.setServers(serverAddresses) {
 		return
 	}
-	logrus.Infof("Updated load balancer %s server addresses -> %v [default: %s]", lb.serviceName, lb.ServerAddresses, lb.defaultServerAddress)
+	logrus.Infof("Updated load balancer %s server addresses -> %v [default: %s]", lb.serviceName, lb.serverAddresses, lb.defaultServerAddress)
 
 	if err := lb.writeConfig(); err != nil {
 		logrus.Warnf("Error updating load balancer %s config: %s", lb.serviceName, err)
@@ -155,6 +154,13 @@ func (lb *LoadBalancer) LoadBalancerServerURL() string {
 	return lb.localServerURL
 }
 
+func (lb *LoadBalancer) ServerAddresses() []string {
+	if lb == nil {
+		return nil
+	}
+	return lb.serverAddresses
+}
+
 func (lb *LoadBalancer) dialContext(ctx context.Context, network, _ string) (net.Conn, error) {
 	lb.mutex.RLock()
 	defer lb.mutex.RUnlock()

pkg/agent/loadbalancer/servers.go

@@ -24,7 +24,7 @@ func (lb *LoadBalancer) setServers(serverAddresses []string) bool {
 	defer lb.mutex.Unlock()
 
 	newAddresses := sets.NewString(serverAddresses...)
-	curAddresses := sets.NewString(lb.ServerAddresses...)
+	curAddresses := sets.NewString(lb.serverAddresses...)
 	if newAddresses.Equal(curAddresses) {
 		return false
 	}
@@ -53,8 +53,8 @@ func (lb *LoadBalancer) setServers(serverAddresses []string) bool {
 		}
 	}
 
-	lb.ServerAddresses = serverAddresses
-	lb.randomServers = append([]string{}, lb.ServerAddresses...)
+	lb.serverAddresses = serverAddresses
+	lb.randomServers = append([]string{}, lb.serverAddresses...)
 	rand.Shuffle(len(lb.randomServers), func(i, j int) {
 		lb.randomServers[i], lb.randomServers[j] = lb.randomServers[j], lb.randomServers[i]
 	})
@@ -155,7 +155,7 @@ func (lb *LoadBalancer) SetDefault(serverAddress string) {
 	lb.mutex.Lock()
 	defer lb.mutex.Unlock()
 
-	hasDefaultServer := slices.Contains(lb.ServerAddresses, lb.defaultServerAddress)
+	hasDefaultServer := slices.Contains(lb.serverAddresses, lb.defaultServerAddress)
 	// if the old default server is not currently in use, remove it from the server map
 	if server := lb.servers[lb.defaultServerAddress]; server != nil && !hasDefaultServer {
 		defer server.closeAll()
@@ -211,7 +211,7 @@ func (lb *LoadBalancer) runHealthChecks(ctx context.Context) {
 		// If there is at least one healthy server, and the default server is not in the server list,
 		// close all the connections to the default server so that clients reconnect and switch over
 		// to a preferred server.
-		hasDefaultServer := slices.Contains(lb.ServerAddresses, lb.defaultServerAddress)
+		hasDefaultServer := slices.Contains(lb.serverAddresses, lb.defaultServerAddress)
 		if healthyServerExists && !hasDefaultServer {
 			if server, ok := lb.servers[lb.defaultServerAddress]; ok {
 				defer server.closeAll()

pkg/etcd/etcdproxy.go

@@ -51,7 +51,7 @@ func (e *etcdproxy) Update(addresses []string) {
 	e.etcdLB.Update(addresses)
 
 	validEndpoint := map[string]bool{}
-	for _, address := range e.etcdLB.ServerAddresses {
+	for _, address := range e.etcdLB.ServerAddresses() {
 		validEndpoint[address] = true
 		if _, ok := e.disconnect[address]; !ok {
 			ctx, cancel := context.WithCancel(context.Background())