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forwarder.go
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forwarder.go
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package pkg
import (
"context"
"fmt"
"net/http"
"sort"
"strconv"
"strings"
"sync/atomic"
"time"
"go.uber.org/zap"
"go.uber.org/zap/zapio"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/kubernetes/scheme"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/client-go/tools/portforward"
"k8s.io/client-go/transport/spdy"
"k8s.io/kubectl/pkg/polymorphichelpers"
"k8s.io/kubectl/pkg/util"
"k8s.io/kubectl/pkg/util/podutils"
)
type Forwarder struct {
config *rest.Config
restClient rest.Interface
target Target
logger *zap.Logger
forwarding atomic.Bool
cancel context.CancelFunc
exitCh chan bool
}
func NewForwarder(kubeconfig string, target Target) (*Forwarder, error) {
config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
if err != nil {
return nil, err
}
config.APIPath = "/api"
config.GroupVersion = &corev1.SchemeGroupVersion
config.NegotiatedSerializer = scheme.Codecs.WithoutConversion()
restClient, err := rest.RESTClientFor(config)
if err != nil {
return nil, err
}
return &Forwarder{
config: config,
restClient: restClient,
target: target,
logger: zap.L().Named(target.Name),
}, nil
}
func (f *Forwarder) Run(ctx context.Context) {
go func() {
ctx, cancel := context.WithCancel(ctx)
f.cancel = cancel
timeout := 1 * time.Second
for {
err := f.forward(ctx)
if err != nil {
if timeout < 30*time.Second {
timeout *= 2
}
f.logger.Error("failed to forward", zap.Error(err))
} else {
timeout = 1 * time.Second
}
select {
case <-ctx.Done():
return
case <-time.After(timeout):
}
}
}()
}
func (f *Forwarder) Stop() {
select {
case <-f.exitCh:
return
default:
close(f.exitCh)
f.cancel()
}
}
func (f *Forwarder) isStopped() bool {
select {
case <-f.exitCh:
return true
default:
return false
}
}
func (f *Forwarder) getObject(ctx context.Context, clientset *kubernetes.Clientset) (runtime.Object, error) {
var obj runtime.Object
var err error
switch f.target.ObjectType {
case "Deployment":
obj, err = clientset.AppsV1().Deployments(f.target.Namespace).Get(ctx, f.target.Name, metav1.GetOptions{})
case "StatefulSet":
obj, err = clientset.AppsV1().StatefulSets(f.target.Namespace).Get(ctx, f.target.Name, metav1.GetOptions{})
case "Service":
obj, err = clientset.CoreV1().Services(f.target.Namespace).Get(ctx, f.target.Name, metav1.GetOptions{})
}
if err != nil {
return nil, err
}
return obj, nil
}
func (f *Forwarder) forward(ctx context.Context) error {
defer f.forwarding.Store(false)
clientset, err := kubernetes.NewForConfig(f.config)
if err != nil {
return err
}
obj, err := f.getObject(ctx, clientset)
if err != nil {
return err
}
namespace, selector, err := polymorphichelpers.SelectorsForObject(obj)
if err != nil {
f.logger.Error("cannot attach to", zap.String("type", fmt.Sprintf("%T", obj)), zap.Error(err))
return err
}
sortBy := func(pods []*corev1.Pod) sort.Interface { return sort.Reverse(podutils.ActivePods(pods)) }
pod, _, err := polymorphichelpers.GetFirstPod(clientset.CoreV1(), namespace, selector.String(), 1*time.Second, sortBy)
if err != nil {
f.logger.Error("failed to get first pod", zap.Error(err))
return err
}
//TODO: check pod status and rbac
var ports []string
if f.target.ObjectType == "Service" {
ports, err = translatePorts(f.target.Ports, obj.(*corev1.Service), pod)
f.logger.Info("translated ports", zap.Strings("orig", f.target.Ports), zap.Strings("translated", ports))
} else {
ports = f.target.Ports
}
f.logger.Info("found pod", zap.String("pod", pod.Namespace+"/"+pod.Name))
req := f.restClient.Post().
Resource("pods").
Namespace(pod.Namespace).
Name(pod.Name).
SubResource("portforward")
transport, upgrader, err := spdy.RoundTripperFor(f.config)
if err != nil {
f.logger.Error("failed to RoundTripperFor", zap.Error(err))
return err
}
dialer := spdy.NewDialer(upgrader, &http.Client{Transport: transport}, "POST", req.URL())
l := f.logger.WithOptions(zap.WithCaller(false)).With(zap.String("forwarder", f.target.String()))
stdoutLogger := &zapio.Writer{Log: l, Level: zap.InfoLevel}
stderrLogger := &zapio.Writer{Log: l, Level: zap.ErrorLevel}
stopChan := make(chan struct{})
readyChan := make(chan struct{})
fw, err := portforward.NewOnAddresses(dialer, []string{"localhost"}, ports, stopChan, readyChan, stdoutLogger, stderrLogger)
if err != nil {
f.logger.Error("failed to NewOnAddresses", zap.Error(err))
return err
}
go func() {
//TODO: exit goroutine when connection lost
<-ctx.Done()
f.logger.Info("stop forwarding")
stopChan <- struct{}{}
}()
f.forwarding.Store(true)
f.logger.Info("start forwarding")
err = fw.ForwardPorts()
if err != nil {
f.logger.Error("failed to ForwardPorts", zap.Error(err))
return err
}
f.logger.Info("lost connection")
return nil
}
func (f *Forwarder) isForwarding() bool {
return f.forwarding.Load()
}
func translatePorts(ports []string, svc *corev1.Service, pod *corev1.Pod) ([]string, error) {
var translated []string
for _, port := range ports {
var localPort, remotePort string
parts := strings.Split(port, ":")
if len(parts) == 1 {
localPort = parts[0]
remotePort = parts[0]
} else if len(parts) == 2 {
localPort = parts[0]
remotePort = parts[1]
} else {
return nil, fmt.Errorf("invalid port: %s", port)
}
portnum, err := strconv.Atoi(remotePort)
if err != nil {
svcPort, err := util.LookupServicePortNumberByName(*svc, remotePort)
if err != nil {
return nil, err
}
portnum = int(svcPort)
if localPort == remotePort {
localPort = strconv.Itoa(portnum)
}
}
containerPort, err := util.LookupContainerPortNumberByServicePort(*svc, *pod, int32(portnum))
if err != nil {
return nil, err
}
remotePort = strconv.Itoa(int(containerPort))
if localPort != remotePort {
translated = append(translated, fmt.Sprintf("%s:%s", localPort, remotePort))
} else {
translated = append(translated, remotePort)
}
}
return translated, nil
}