persist api/staking ports on node restart

local/network.go

@@ -1109,17 +1109,23 @@ func (ln *localNetwork) buildFlags(
 		return buildFlagsReturn{}, err
 	}
 
-	// Use random free API port unless given in config file
-	apiPort, err := getPort(nodeConfig.Flags, configFile, config.HTTPPortKey)
-	if err != nil {
-		return buildFlagsReturn{}, err
+	// Prefer API port and P2P (staking) port from nodeConfig
+	apiPort, p2pPort := nodeConfig.ApiPort, nodeConfig.StakingPort
+
+	if apiPort == 0 {
+		// Use random free API port unless given in config file
+		apiPort, err = getPort(nodeConfig.Flags, configFile, config.HTTPPortKey)
+		if err != nil {
+			return buildFlagsReturn{}, err
+		}
 	}
 
-	// Use a random free P2P (staking) port unless given in config file
-	// Use random free API port unless given in config file
-	p2pPort, err := getPort(nodeConfig.Flags, configFile, config.StakingPortKey)
-	if err != nil {
-		return buildFlagsReturn{}, err
+	if p2pPort == 0 {
+		// Use a random free P2P (staking) port unless given in config file
+		p2pPort, err = getPort(nodeConfig.Flags, configFile, config.StakingPortKey)
+		if err != nil {
+			return buildFlagsReturn{}, err
+		}
 	}
 
 	// Flags for AvalancheGo

network/node/node.go

@@ -83,6 +83,11 @@ type Config struct {
 	RedirectStdout bool `json:"redirectStdout"`
 	// If non-nil, direct this node's Stderr to os.Stderr
 	RedirectStderr bool `json:"redirectStderr"`
+
+	// If non-zero, prefer these ports to the one specified in the config file
+	// Used to persist node ports accross restart
+	ApiPort     uint16
+	StakingPort uint16
 }
 
 // Validate returns an error if this config is invalid

server/server.go

@@ -877,6 +877,10 @@ func (s *server) RestartNode(ctx context.Context, req *rpcpb.RestartNodeRequest)
 		return nil, fmt.Errorf("failed to generate json node config string: %w", err)
 	}
 
+	// keep the same api & staking ports across the restart
+	nodeConfig.ApiPort = node.GetAPIPort()
+	nodeConfig.StakingPort = node.GetP2PPort()
+
 	nodeConfig.BinaryPath = nodeInfo.ExecPath
 	nodeConfig.RedirectStdout = s.cfg.RedirectNodesOutput
 	nodeConfig.RedirectStderr = s.cfg.RedirectNodesOutput