add a stub for Caddyfile controller

internal/machine/caddyfile/controller.go

@@ -0,0 +1,35 @@
+package caddyfile
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"uncloud/internal/machine/store"
+)
+
+// Controller monitors container changes in the cluster store and generates a configuration file for Caddy reverse
+// proxy. The generated Caddyfile allows Caddy to route external traffic to service containers across the internal
+// network.
+type Controller struct {
+	store *store.Store
+	path  string
+	mu    sync.Mutex
+}
+
+func NewController(store *store.Store, path string) (*Controller, error) {
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return nil, fmt.Errorf("create parent directory for Caddyfile '%s': %w", dir, err)
+	}
+
+	return &Controller{
+		store: store,
+		path:  path,
+	}, nil
+}
+
+func (cc *Controller) Run(ctx context.Context) error {
+	return nil
+}

internal/machine/machine.go

@@ -25,6 +25,7 @@ import (
 	"uncloud/internal/fs"
 	"uncloud/internal/machine/api/pb"
 	apiproxy "uncloud/internal/machine/api/proxy"
+	"uncloud/internal/machine/caddyfile"
 	"uncloud/internal/machine/cluster"
 	"uncloud/internal/machine/corroservice"
 	machinedocker "uncloud/internal/machine/docker"
@@ -39,7 +40,7 @@ const (
 )
 
 type Config struct {
-	// DataDir is the directory where the machine stores its persistent state.
+	// DataDir is the directory where the machine stores its persistent state. Default is /var/lib/uncloud.
 	DataDir         string
 	MachineSockPath string
 	UncloudSockPath string
@@ -54,6 +55,10 @@ type Config struct {
 
 	// DockerClient manages system and user containers using the local Docker daemon.
 	DockerClient *client.Client
+
+	// CaddyfilePath specifies where the machine generates the Caddy reverse proxy configuration file for routing
+	// external traffic to service containers across the internal network. Default is DataDir/caddy/Caddyfile.
+	CaddyfilePath string
 }
 
 // SetDefaults returns a new Config with default values set where not provided.
@@ -115,6 +120,11 @@ func (c *Config) SetDefaults() (*Config, error) {
 			cfg.CorrosionService = corroservice.DefaultSystemdService(cfg.CorrosionDir)
 		}
 	}
+
+	if cfg.CaddyfilePath == "" {
+		cfg.CaddyfilePath = filepath.Join(cfg.DataDir, "caddy", "Caddyfile")
+	}
+
 	return &cfg, nil
 }
 
@@ -347,12 +357,18 @@ func (m *Machine) Run(ctx context.Context) error {
 						),
 					)
 
+					caddyfileCtrl, err := caddyfile.NewController(m.store, m.config.CaddyfilePath)
+					if err != nil {
+						return fmt.Errorf("create Caddyfile controller: %w", err)
+					}
+
 					ctrl, err = newNetworkController(
 						m.state,
 						m.store,
 						proxyServer,
 						m.config.CorrosionService,
 						m.config.DockerClient,
+						caddyfileCtrl,
 					)
 					if err != nil {
 						return fmt.Errorf("initialise network controller: %w", err)

internal/machine/network.go

@@ -15,6 +15,7 @@ import (
 	"strconv"
 	"time"
 	"uncloud/internal/machine/api/pb"
+	"uncloud/internal/machine/caddyfile"
 	"uncloud/internal/machine/corroservice"
 	"uncloud/internal/machine/docker"
 	"uncloud/internal/machine/network"
@@ -32,16 +33,22 @@ type networkController struct {
 	wgnet           *network.WireGuardNetwork
 	endpointChanges <-chan network.EndpointChangeEvent
 
-	server       *grpc.Server
-	corroService corroservice.Service
-	dockerCli    *client.Client
+	server        *grpc.Server
+	corroService  corroservice.Service
+	dockerCli     *client.Client
+	caddyfileCtrl *caddyfile.Controller
 
 	// TODO: DNS server/resolver listening on the machine IP, e.g. 10.210.0.1:53. It can't listen on 127.0.X.X
 	//  like resolved does because it needs to be reachable from both the host and the containers.
 }
 
 func newNetworkController(
-	state *State, store *store.Store, server *grpc.Server, corroService corroservice.Service, dockerCli *client.Client,
+	state *State,
+	store *store.Store,
+	server *grpc.Server,
+	corroService corroservice.Service,
+	dockerCli *client.Client,
+	caddyfileCtrl *caddyfile.Controller,
 ) (
 	*networkController, error,
 ) {
@@ -60,6 +67,7 @@ func newNetworkController(
 		server:          server,
 		corroService:    corroService,
 		dockerCli:       dockerCli,
+		caddyfileCtrl:   caddyfileCtrl,
 	}, nil
 }
 
@@ -139,7 +147,7 @@ func (nc *networkController) Run(ctx context.Context) error {
 							break
 						}
 					}
-					if err = nc.state.Save(); err != nil {
+					if err := nc.state.Save(); err != nil {
 						slog.Error("Failed to save machine state.", "err", err)
 					}
 					nc.state.mu.Unlock()
@@ -155,13 +163,22 @@ func (nc *networkController) Run(ctx context.Context) error {
 
 	errGroup.Go(
 		func() error {
-			if err = nc.wgnet.Run(ctx); err != nil {
+			if err := nc.wgnet.Run(ctx); err != nil {
 				return fmt.Errorf("WireGuard network failed: %w", err)
 			}
 			return nil
 		},
 	)
 
+	errGroup.Go(func() error {
+		slog.Info("Starting Caddyfile controller.")
+		if err := nc.caddyfileCtrl.Run(ctx); err != nil {
+			//goland:noinspection GoErrorStringFormat
+			return fmt.Errorf("Caddyfile controller failed: %w", err)
+		}
+		return nil
+	})
+
 	// Wait for the context to be done and stop the network API server.
 	errGroup.Go(
 		func() error {
@@ -214,7 +231,8 @@ func (nc *networkController) prepareAndWatchDocker(ctx context.Context) error {
 	return nil
 }
 
-// handleMachineChanges subscribes to machine changes in the cluster and reconfigures the network peers accordingly.
+// handleMachineChanges subscribes to machine changes in the cluster and reconfigures the network peers accordingly
+// when changes occur.
 func (nc *networkController) handleMachineChanges(ctx context.Context) error {
 	for {
 		// Retry to subscribe to machine changes indefinitely until the context is done.

internal/machine/store/store.go

@@ -88,7 +88,7 @@ func (s *Store) ListMachines(ctx context.Context) ([]*pb.MachineInfo, error) {
 }
 
 // SubscribeMachines returns a list of machines and a channel that signals changes to the list. The channel doesn't
-// receive any values, it's just signals when a machine has been added, updated, or deleted in the database.
+// receive any values, it just signals when a machine has been added, updated, or deleted in the database.
 func (s *Store) SubscribeMachines(ctx context.Context) ([]*pb.MachineInfo, <-chan struct{}, error) {
 	sub, err := s.corro.SubscribeContext(ctx, "SELECT info FROM machines ORDER BY name", nil, false)
 	if err != nil {