Add support for Attach API functionality (#1090)

Co-authored-by: Pablo Borrelli <pablo.borrelli0@gmail.com>

node/api/attach.go

@@ -0,0 +1,139 @@
+// Copyright © 2017 The virtual-kubelet 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 api
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/gorilla/mux"
+	"github.com/virtual-kubelet/virtual-kubelet/errdefs"
+	"github.com/virtual-kubelet/virtual-kubelet/internal/kubernetes/remotecommand"
+	"k8s.io/apimachinery/pkg/types"
+	remoteutils "k8s.io/client-go/tools/remotecommand"
+)
+
+// ContainerAttachHandlerFunc defines the handler function used for "execing" into a
+// container in a pod.
+type ContainerAttachHandlerFunc func(ctx context.Context, namespace, podName, containerName string, attach AttachIO) error
+
+// HandleContainerAttach makes an http handler func from a Provider which execs a command in a pod's container
+// Note that this handler currently depends on gorrilla/mux to get url parts as variables.
+// TODO(@cpuguy83): don't force gorilla/mux on consumers of this function
+func HandleContainerAttach(h ContainerAttachHandlerFunc, opts ...ContainerExecHandlerOption) http.HandlerFunc {
+	if h == nil {
+		return NotImplemented
+	}
+
+	var cfg ContainerExecHandlerConfig
+	for _, o := range opts {
+		o(&cfg)
+	}
+
+	if cfg.StreamIdleTimeout == 0 {
+		cfg.StreamIdleTimeout = 30 * time.Second
+	}
+	if cfg.StreamCreationTimeout == 0 {
+		cfg.StreamCreationTimeout = 30 * time.Second
+	}
+
+	return handleError(func(w http.ResponseWriter, req *http.Request) error {
+		vars := mux.Vars(req)
+
+		namespace := vars["namespace"]
+		pod := vars["pod"]
+		container := vars["container"]
+
+		supportedStreamProtocols := strings.Split(req.Header.Get("X-Stream-Protocol-Version"), ",")
+
+		streamOpts, err := getExecOptions(req)
+		if err != nil {
+			return errdefs.AsInvalidInput(err)
+		}
+
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+
+		attach := &containerAttachContext{ctx: ctx, h: h, pod: pod, namespace: namespace, container: container}
+		remotecommand.ServeAttach(
+			w,
+			req,
+			attach,
+			"",
+			"",
+			container,
+			streamOpts,
+			cfg.StreamIdleTimeout,
+			cfg.StreamCreationTimeout,
+			supportedStreamProtocols,
+		)
+
+		return nil
+	})
+}
+
+type containerAttachContext struct {
+	h                         ContainerAttachHandlerFunc
+	namespace, pod, container string
+	ctx                       context.Context
+}
+
+// AttachToContainer Implements remotecommand.Attacher
+// This is called by remotecommand.ServeAttach
+func (c *containerAttachContext) AttachToContainer(name string, uid types.UID, container string, in io.Reader, out, err io.WriteCloser, tty bool, resize <-chan remoteutils.TerminalSize, timeout time.Duration) error {
+
+	eio := &execIO{
+		tty:    tty,
+		stdin:  in,
+		stdout: out,
+		stderr: err,
+	}
+
+	if tty {
+		eio.chResize = make(chan TermSize)
+	}
+
+	ctx, cancel := context.WithCancel(c.ctx)
+	defer cancel()
+
+	if tty {
+		go func() {
+			send := func(s remoteutils.TerminalSize) bool {
+				select {
+				case eio.chResize <- TermSize{Width: s.Width, Height: s.Height}:
+					return false
+				case <-ctx.Done():
+					return true
+				}
+			}
+
+			for {
+				select {
+				case s := <-resize:
+					if send(s) {
+						return
+					}
+				case <-ctx.Done():
+					return
+				}
+			}
+		}()
+	}
+
+	return c.h(c.ctx, c.namespace, c.pod, c.container, eio)
+}

node/api/server.go

@@ -34,8 +34,9 @@ type ServeMux interface {
 }
 
 type PodHandlerConfig struct { //nolint:golint
-	RunInContainer   ContainerExecHandlerFunc
-	GetContainerLogs ContainerLogsHandlerFunc
+	RunInContainer    ContainerExecHandlerFunc
+	AttachToContainer ContainerAttachHandlerFunc
+	GetContainerLogs  ContainerLogsHandlerFunc
 	// GetPods is meant to enumerate the pods that the provider knows about
 	GetPods PodListerFunc
 	// GetPodsFromKubernetes is meant to enumerate the pods that the node is meant to be running
@@ -68,6 +69,14 @@ func PodHandler(p PodHandlerConfig, debug bool) http.Handler {
 			WithExecStreamIdleTimeout(p.StreamIdleTimeout),
 		),
 	).Methods("POST", "GET")
+	r.HandleFunc(
+		"/attach/{namespace}/{pod}/{container}",
+		HandleContainerAttach(
+			p.AttachToContainer,
+			WithExecStreamCreationTimeout(p.StreamCreationTimeout),
+			WithExecStreamIdleTimeout(p.StreamIdleTimeout),
+		),
+	).Methods("POST", "GET")
 
 	if p.GetStatsSummary != nil {
 		f := HandlePodStatsSummary(p.GetStatsSummary)

node/nodeutil/provider.go

@@ -28,6 +28,10 @@ type Provider interface {
 	// between in/out/err and the container's stdin/stdout/stderr.
 	RunInContainer(ctx context.Context, namespace, podName, containerName string, cmd []string, attach api.AttachIO) error
 
+	// AttachToContainer attaches to the executing process of a container in the pod, copying data
+	// between in/out/err and the container's stdin/stdout/stderr.
+	AttachToContainer(ctx context.Context, namespace, podName, containerName string, attach api.AttachIO) error
+
 	// GetStatsSummary gets the stats for the node, including running pods
 	GetStatsSummary(context.Context) (*statsv1alpha1.Summary, error)
 
@@ -58,9 +62,10 @@ func AttachProviderRoutes(mux api.ServeMux) NodeOpt {
 	return func(cfg *NodeConfig) error {
 		cfg.routeAttacher = func(p Provider, cfg NodeConfig, pods corev1listers.PodLister) {
 			mux.Handle("/", api.PodHandler(api.PodHandlerConfig{
-				RunInContainer:   p.RunInContainer,
-				GetContainerLogs: p.GetContainerLogs,
-				GetPods:          p.GetPods,
+				RunInContainer:    p.RunInContainer,
+				AttachToContainer: p.AttachToContainer,
+				GetContainerLogs:  p.GetContainerLogs,
+				GetPods:           p.GetPods,
 				GetPodsFromKubernetes: func(context.Context) ([]*v1.Pod, error) {
 					return pods.List(labels.Everything())
 				},