Forward Lima guest HTTP port to host (#600)

This isn't used yet but will give us more options in the future for
different "host resolvers" instead of only relying on vzNAT's networking
that makes the guest IP reachable on the host.

On Linux hosts for example, vzNAT isn't available so we would some sort
of rever proxy implementation and that can only work with the guest HTTP
port forwarded on the host.

There's a new CLI option to control this but it defaults to `true`.

Author: swalkinshaw

cli_config/cli_config.go

@@ -17,11 +17,12 @@ type VmImage struct {
 }
 
 type VmConfig struct {
-	Manager       string    `yaml:"manager"`
-	HostsResolver string    `yaml:"hosts_resolver"`
-	Images        []VmImage `yaml:"images"`
-	Ubuntu        string    `yaml:"ubuntu"`
-	InstanceName  string    `yaml:"instance_name"`
+	Manager         string    `yaml:"manager"`
+	HostsResolver   string    `yaml:"hosts_resolver"`
+	Images          []VmImage `yaml:"images"`
+	Ubuntu          string    `yaml:"ubuntu"`
+	InstanceName    string    `yaml:"instance_name"`
+	ForwardHttpPort bool      `yaml:"forward_http_port"`
 }
 
 type Config struct {

pkg/lima/manager.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net"
 	"os"
 	"path/filepath"
 	"strings"
@@ -27,10 +28,17 @@ var (
 	ErrUnsupportedOS = errors.New("unsupported OS or macOS version. The macOS Virtualization Framework requires macOS 13.0 (Ventura) or later.")
 )
 
+type PortFinder interface {
+	Resolve() (int, error)
+}
+
+type TCPPortFinder struct{}
+
 type Manager struct {
 	ConfigPath    string
 	Sites         map[string]*trellis.Site
 	HostsResolver vm.HostsResolver
+	PortFinder    PortFinder
 	ui            cli.Ui
 	trellis       *trellis.Trellis
 }
@@ -55,6 +63,7 @@ func NewManager(trellis *trellis.Trellis, ui cli.Ui) (manager *Manager, err erro
 		ConfigPath:    limaConfigPath,
 		Sites:         trellis.Environments["development"].WordPressSites,
 		HostsResolver: hostsResolver,
+		PortFinder:    &TCPPortFinder{},
 		trellis:       trellis,
 		ui:            ui,
 	}
@@ -78,7 +87,10 @@ func (m *Manager) GetInstance(name string) (Instance, bool) {
 }
 
 func (m *Manager) CreateInstance(name string) error {
-	instance := m.newInstance(name)
+	instance, err := m.newInstance(name)
+	if err != nil {
+		return err
+	}
 
 	cmd := command.WithOptions(
 		command.WithTermOutput(),
@@ -172,7 +184,8 @@ func (m *Manager) StartInstance(name string) error {
 
 	instance.Username = string(user)
 
-	// Hydrate instance with data from limactl that is only available after starting (mainly the forwarded SSH local port)
+	// Hydrate instance with data from limactl that is only available after
+	// starting (mainly the forwarded local ports)
 	err = m.hydrateInstance(&instance)
 	if err != nil {
 		return err
@@ -232,7 +245,7 @@ func (m *Manager) initInstance(instance *Instance) {
 	instance.Sites = m.Sites
 }
 
-func (m *Manager) newInstance(name string) Instance {
+func (m *Manager) newInstance(name string) (Instance, error) {
 	instance := Instance{Name: name}
 	m.initInstance(&instance)
 
@@ -249,9 +262,24 @@ func (m *Manager) newInstance(name string) Instance {
 		images = imagesFromVersion(m.trellis.CliConfig.Vm.Ubuntu)
 	}
 
-	config := Config{Images: images}
+	portForwards := []PortForward{}
+
+	if m.trellis.CliConfig.Vm.ForwardHttpPort {
+		httpForwardPort, err := m.PortFinder.Resolve()
+		if err != nil {
+			return Instance{}, fmt.Errorf("Could not find a local free port for HTTP forwarding: %v", err)
+		}
+
+		portForwards = append(portForwards, PortForward{
+			GuestPort: 80,
+			HostPort:  httpForwardPort,
+		},
+		)
+	}
+
+	config := Config{Images: images, PortForwards: portForwards}
 	instance.Config = config
-	return instance
+	return instance, nil
 }
 
 func (m *Manager) createConfigPath() error {
@@ -329,3 +357,31 @@ func ensureRequirements() error {
 func imagesFromVersion(version string) []Image {
 	return UbuntuImages[version]
 }
+
+func (p *TCPPortFinder) Resolve() (int, error) {
+	lAddr0, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:0")
+	if err != nil {
+		return 0, err
+	}
+
+	l, err := net.ListenTCP("tcp4", lAddr0)
+	if err != nil {
+		return 0, err
+	}
+
+	defer func() { _ = l.Close() }()
+	lAddr := l.Addr()
+
+	lTCPAddr, ok := lAddr.(*net.TCPAddr)
+	if !ok {
+		return 0, fmt.Errorf("expected *net.TCPAddr, got %v", lAddr)
+	}
+
+	port := lTCPAddr.Port
+
+	if port <= 0 {
+		return 0, fmt.Errorf("unexpected port %d", port)
+	}
+
+	return port, nil
+}

pkg/lima/manager_test.go

@@ -15,6 +15,12 @@ type MockHostsResolver struct {
 	Hosts map[string]string
 }
 
+type MockPortFinder struct{}
+
+func (p *MockPortFinder) Resolve() (int, error) {
+	return 60720, nil
+}
+
 func TestNewManager(t *testing.T) {
 	defer trellis.LoadFixtureProject(t)()
 	trellis := trellis.NewTrellis()
@@ -120,7 +126,13 @@ func TestNewInstanceUbuntuVersion(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	instance := manager.newInstance("test")
+	manager.PortFinder = &MockPortFinder{}
+
+	instance, err := manager.newInstance("test")
+
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	if instance.Name != "test" {
 		t.Errorf("expected instance name to be %q, got %q", "test", instance.Name)
@@ -133,6 +145,14 @@ func TestNewInstanceUbuntuVersion(t *testing.T) {
 	if instance.Config.Images[0].Alias != "focal" {
 		t.Errorf("expected instance config to have focal image, got %q", instance.Config.Images[0].Alias)
 	}
+
+	if len(instance.Config.PortForwards) != 1 {
+		t.Errorf("expected instance config to have 1 port forwards, got %d", len(instance.Config.PortForwards))
+	}
+
+	if instance.Config.PortForwards[0].GuestPort != 80 || instance.Config.PortForwards[0].HostPort != 60720 {
+		t.Errorf("expected instance config to have port forward guest 80 to host 60720, got guest %d to host %d", instance.Config.PortForwards[0].GuestPort, instance.Config.PortForwards[0].HostPort)
+	}
 }
 func TestInstances(t *testing.T) {
 	defer trellis.LoadFixtureProject(t)()
@@ -197,6 +217,7 @@ func TestCreateInstance(t *testing.T) {
 
 	hostsStorage := make(map[string]string)
 	manager.HostsResolver = &MockHostsResolver{Hosts: hostsStorage}
+	manager.PortFinder = &MockPortFinder{}
 
 	instanceName := "test"
 	sshPort := 60720

trellis/trellis.go

@@ -36,10 +36,11 @@ var DefaultCliConfig = cli_config.Config{
 	Open:                    make(map[string]string),
 	VirtualenvIntegration:   true,
 	Vm: cli_config.VmConfig{
-		Manager:       "auto",
-		HostsResolver: "hosts_file",
-		Ubuntu:        "24.04",
-		InstanceName:  "",
+		Manager:         "auto",
+		HostsResolver:   "hosts_file",
+		Ubuntu:          "24.04",
+		InstanceName:    "",
+		ForwardHttpPort: true,
 	},
 }