tiltfile: custom host in port forwards

internal/containerupdate/synclet_manager.go

@@ -202,7 +202,7 @@ func newSyncletClient(ctx context.Context, kCli k8s.Client, syncletImageRef side
 
 	// TODO(nick): We need a better way to kill the client when the pod dies.
 	ctx, cancel := context.WithCancel(ctx)
-	pf, err := kCli.CreatePortForwarder(ctx, ns, podID, 0, synclet.Port)
+	pf, err := kCli.CreatePortForwarder(ctx, ns, podID, 0, synclet.Port, "")
 	if err != nil {
 		cancel()
 		return nil, errors.Wrapf(err, "failed opening tunnel to synclet pod '%s'", podID)

internal/engine/portforwardcontroller.go

@@ -158,7 +158,7 @@ func (m *PortForwardController) onePortForward(ctx context.Context, entry portFo
 	ns := entry.namespace
 	podID := entry.podID
 
-	pf, err := m.kClient.CreatePortForwarder(ctx, ns, podID, forward.LocalPort, forward.ContainerPort)
+	pf, err := m.kClient.CreatePortForwarder(ctx, ns, podID, forward.LocalPort, forward.ContainerPort, forward.Host)
 	if err != nil {
 		return err
 	}

internal/k8s/client.go

@@ -88,7 +88,7 @@ type Client interface {
 	ContainerLogs(ctx context.Context, podID PodID, cName container.Name, n Namespace, startTime time.Time) (io.ReadCloser, error)
 
 	// Opens a tunnel to the specified pod+port. Returns the tunnel's local port and a function that closes the tunnel
-	CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int) (PortForwarder, error)
+	CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int, host *string) (PortForwarder, error)
 
 	WatchPods(ctx context.Context, lps labels.Selector) (<-chan *v1.Pod, error)
 

internal/k8s/exploding_client.go

@@ -53,7 +53,7 @@ func (ec *explodingClient) ContainerLogs(ctx context.Context, podID PodID, cName
 	return nil, errors.Wrap(ec.err, "could not set up k8s client")
 }
 
-func (ec *explodingClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int) (PortForwarder, error) {
+func (ec *explodingClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int, host *string) (PortForwarder, error) {
 	return nil, errors.Wrap(ec.err, "could not set up k8s client")
 }
 

internal/k8s/fake_client.go

@@ -323,9 +323,9 @@ func (c *FakeK8sClient) applyWasCalled() bool {
 	return c.Yaml != ""
 }
 
-func (c *FakeK8sClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int) (PortForwarder, error) {
+func (c *FakeK8sClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int, host *string) (PortForwarder, error) {
 	pfc := &(c.FakePortForwardClient)
-	return pfc.CreatePortForwarder(ctx, namespace, podID, optionalLocalPort, remotePort)
+	return pfc.CreatePortForwarder(ctx, namespace, podID, optionalLocalPort, remotePort, host)
 }
 
 func (c *FakeK8sClient) ContainerRuntime(ctx context.Context) container.Runtime {
@@ -398,15 +398,17 @@ type FakePortForwardClient struct {
 	CreatePortForwardCallCount int
 	LastForwardPortPodID       PodID
 	LastForwardPortRemotePort  int
+	LastForwardPortHost        *string
 	LastForwarder              FakePortForwarder
 	LastForwardContext         context.Context
 }
 
-func (c *FakePortForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int) (PortForwarder, error) {
+func (c *FakePortForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int, host *string) (PortForwarder, error) {
 	c.CreatePortForwardCallCount++
 	c.LastForwardContext = ctx
 	c.LastForwardPortPodID = podID
 	c.LastForwardPortRemotePort = remotePort
+	c.LastForwardPortHost = host
 
 	result := FakePortForwarder{
 		localPort: optionalLocalPort,

internal/k8s/portforward.go

@@ -21,7 +21,7 @@ import (
 type PortForwardClient interface {
 	// Creates a new port-forwarder that's bound to the given context's lifecycle.
 	// When the context is canceled, the port-forwarder will close.
-	CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int) (PortForwarder, error)
+	CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int, host *string) (PortForwarder, error)
 }
 
 type PortForwarder interface {
@@ -43,7 +43,7 @@ func (pf portForwarder) LocalPort() int {
 	return pf.localPort
 }
 
-func (k K8sClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int) (PortForwarder, error) {
+func (k K8sClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, optionalLocalPort, remotePort int, host *string) (PortForwarder, error) {
 	localPort := optionalLocalPort
 	if localPort == 0 {
 		// preferably, we'd set the localport to 0, and let the underlying function pick a port for us,
@@ -59,7 +59,7 @@ func (k K8sClient) CreatePortForwarder(ctx context.Context, namespace Namespace,
 		}
 	}
 
-	return k.portForwardClient.CreatePortForwarder(ctx, namespace, podID, localPort, remotePort)
+	return k.portForwardClient.CreatePortForwarder(ctx, namespace, podID, localPort, remotePort, host)
 }
 
 type portForwardClient struct {
@@ -82,7 +82,7 @@ func ProvidePortForwardClient(
 	}
 }
 
-func (c portForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int) (PortForwarder, error) {
+func (c portForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int, host *string) (PortForwarder, error) {
 	transport, upgrader, err := spdy.RoundTripperFor(c.config)
 	if err != nil {
 		return nil, errors.Wrap(err, "error getting roundtripper")
@@ -103,13 +103,27 @@ func (c portForwardClient) CreatePortForwarder(ctx context.Context, namespace Na
 	readyChan := make(chan struct{}, 1)
 
 	ports := []string{fmt.Sprintf("%d:%d", localPort, remotePort)}
-	pf, err := portforward.New(
-		dialer,
-		ports,
-		stopChan,
-		readyChan,
-		logger.Get(ctx).Writer(logger.DebugLvl),
-		logger.Get(ctx).Writer(logger.DebugLvl))
+
+	var pf *portforward.PortForwarder
+	if host == nil {
+		pf, err = portforward.New(
+			dialer,
+			ports,
+			stopChan,
+			readyChan,
+			logger.Get(ctx).Writer(logger.DebugLvl),
+			logger.Get(ctx).Writer(logger.DebugLvl))
+	} else {
+		addresses := []string{*host}
+		pf, err = portforward.NewOnAddresses(
+			dialer,
+			addresses,
+			ports,
+			stopChan,
+			readyChan,
+			logger.Get(ctx).Writer(logger.DebugLvl),
+			logger.Get(ctx).Writer(logger.DebugLvl))
+	}
 	if err != nil {
 		return nil, errors.Wrap(err, "error forwarding port")
 	}
@@ -151,6 +165,6 @@ type explodingPortForwardClient struct {
 	error error
 }
 
-func (c explodingPortForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int) (PortForwarder, error) {
+func (c explodingPortForwardClient) CreatePortForwarder(ctx context.Context, namespace Namespace, podID PodID, localPort int, remotePort int, host *string) (PortForwarder, error) {
 	return nil, c.error
 }

internal/tiltfile/k8s.go

@@ -2,6 +2,7 @@ package tiltfile
 
 import (
 	"fmt"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -775,6 +776,7 @@ func (s *tiltfileState) portForward(thread *starlark.Thread, fn *starlark.Builti
 type portForward struct {
 	local     int
 	container int
+	host      *string
 }
 
 var _ starlark.Value = portForward{}
@@ -800,35 +802,54 @@ func (f portForward) Hash() (uint32, error) {
 func intToPortForward(i starlark.Int) (portForward, error) {
 	n, ok := i.Int64()
 	if !ok {
-		return portForward{}, fmt.Errorf("portForward value %v is not representable as an int64", i)
+		return portForward{}, fmt.Errorf("portForward port value %v is not representable as an int64", i)
 	}
 	if n < 0 || n > 65535 {
-		return portForward{}, fmt.Errorf("portForward value %v is not in the range for a port [0-65535]", n)
+		return portForward{}, fmt.Errorf("portForward port value %v is not in the valid range [0-65535]", n)
 	}
 	return portForward{local: int(n)}, nil
 }
 
+const ipReStr = `^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$`
+const hostnameReStr = `^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$`
+
+var validHost = regexp.MustCompile(ipReStr + "|" + hostnameReStr)
+
 func stringToPortForward(s starlark.String) (portForward, error) {
-	parts := strings.SplitN(string(s), ":", 2)
-	local, err := strconv.Atoi(parts[0])
+	parts := strings.SplitN(string(s), ":", 3)
+
+	var host *string
+	var localString string
+	if len(parts) == 3 {
+		localString = parts[1]
+		host = &parts[0]
+		if !validHost.MatchString(*host) {
+			return portForward{}, fmt.Errorf("portForward host value %q is not a valid hostname or IP address", localString)
+		}
+	} else {
+		localString = parts[0]
+	}
+
+	local, err := strconv.Atoi(localString)
 	if err != nil || local < 0 || local > 65535 {
-		return portForward{}, fmt.Errorf("portForward value %q is not in the range for a port [0-65535]", parts[0])
+		return portForward{}, fmt.Errorf("portForward port value %q is not in the valid range [0-65535]", localString)
 	}
 
 	var container int
-	if len(parts) == 2 {
-		container, err = strconv.Atoi(parts[1])
+	if len(parts) > 1 {
+		last := parts[len(parts)-1]
+		container, err = strconv.Atoi(last)
 		if err != nil || container < 0 || container > 65535 {
-			return portForward{}, fmt.Errorf("portForward value %q is not in the range for a port [0-65535]", parts[1])
+			return portForward{}, fmt.Errorf("portForward port value %q is not in the valid range [0-65535]", last)
 		}
 	}
-	return portForward{local: local, container: container}, nil
+	return portForward{local: local, container: container, host: host}, nil
 }
 
 func (s *tiltfileState) portForwardsToDomain(r *k8sResource) []model.PortForward {
 	var result []model.PortForward
 	for _, pf := range r.portForwards {
-		result = append(result, model.PortForward{LocalPort: pf.local, ContainerPort: pf.container})
+		result = append(result, model.PortForward{LocalPort: pf.local, ContainerPort: pf.container, Host: pf.host})
 	}
 	return result
 }