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portforward.go
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portforward.go
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/*
Copyright 2021 The Dapr Authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package kubernetes
import (
"fmt"
"io/ioutil"
"net/http"
"net/url"
"os"
"strings"
core_v1 "k8s.io/api/core/v1"
k8s "k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/portforward"
"k8s.io/client-go/transport/spdy"
)
// PortForward provides a port-forward connection in a kubernetes cluster.
type PortForward struct {
Config *rest.Config
Method string
URL *url.URL
Host string
LocalPort int
RemotePort int
EmitLogs bool
StopCh chan struct{}
ReadyCh chan struct{}
}
// NewPortForward returns an instance of PortForward struct that can be used
// for establishing port-forwarding connection to a pod in kubernetes cluster,
// specified by namespace and deployName.
func NewPortForward(
config *rest.Config,
namespace, deployName string,
host string, localPort, remotePort int,
emitLogs bool,
) (*PortForward, error) {
client, err := k8s.NewForConfig(config)
if err != nil {
return nil, err
}
podList, err := ListPods(client, namespace, nil)
if err != nil {
return nil, err
}
podName := ""
for _, pod := range podList.Items {
if pod.Status.Phase == core_v1.PodRunning {
if strings.HasPrefix(pod.Name, deployName) {
podName = pod.Name
break
}
}
}
if podName == "" {
return nil, fmt.Errorf("no running pods found for %s", deployName)
}
req := client.CoreV1().RESTClient().Post().
Resource("pods").
Namespace(namespace).
Name(podName).
SubResource("portforward")
return &PortForward{
Config: config,
Method: "POST",
URL: req.URL(),
Host: host,
LocalPort: localPort,
RemotePort: remotePort,
EmitLogs: emitLogs,
StopCh: make(chan struct{}, 1),
ReadyCh: make(chan struct{}),
}, nil
}
// run creates port-forward connection and blocks
// until Stop() is called.
func (pf *PortForward) run() error {
transport, upgrader, err := spdy.RoundTripperFor(pf.Config)
if err != nil {
return err
}
out := ioutil.Discard
errOut := ioutil.Discard
if pf.EmitLogs {
out = os.Stdout
errOut = os.Stderr
}
ports := []string{fmt.Sprintf("%d:%d", pf.LocalPort, pf.RemotePort)}
dialer := spdy.NewDialer(upgrader, &http.Client{Transport: transport}, pf.Method, pf.URL)
fw, err := portforward.NewOnAddresses(dialer, []string{pf.Host}, ports, pf.StopCh, pf.ReadyCh, out, errOut)
if err != nil {
return err
}
return fw.ForwardPorts()
}
// Init creates and runs a port-forward connection.
// This function blocks until connection is established.
// Note: Caller should call Stop() to finish the connection.
func (pf *PortForward) Init() error {
failure := make(chan error)
go func() {
if err := pf.run(); err != nil {
failure <- err
}
}()
select {
// if `pf.run()` succeeds, block until terminated.
case <-pf.ReadyCh:
// if failure, causing a receive `<-failure` and returns the error.
case err := <-failure:
return err
}
return nil
}
// Stop terminates port-forwarding connection.
func (pf *PortForward) Stop() {
close(pf.StopCh)
}
// GetStop returns StopCh for a PortForward instance.
// Receiving on StopCh will block until the port forwarding stops.
func (pf *PortForward) GetStop() <-chan struct{} {
return pf.StopCh
}