Add support for Attach API functionality (#1090)

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

cmd/virtual-kubelet/internal/provider/mock/mock.go

@@ -301,6 +301,13 @@ func (p *MockProvider) RunInContainer(ctx context.Context, namespace, name, cont
 	return nil
 }
 
+// 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.
+func (p *MockProvider) AttachToContainer(ctx context.Context, namespace, name, container string, attach api.AttachIO) error {
+	log.G(ctx).Infof("receive AttachToContainer %q", container)
+	return nil
+}
+
 // GetPodStatus returns the status of a pod by name that is "running".
 // returns nil if a pod by that name is not found.
 func (p *MockProvider) GetPodStatus(ctx context.Context, namespace, name string) (*v1.PodStatus, error) {

internal/kubernetes/remotecommand/attach.go

@@ -0,0 +1,79 @@
+/*
+Copyright 2016 The Kubernetes 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 remotecommand
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+	remotecommandconsts "k8s.io/apimachinery/pkg/util/remotecommand"
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/client-go/tools/remotecommand"
+	utilexec "k8s.io/utils/exec"
+)
+
+// Attacher knows how to attach to a container in a pod.
+type Attacher interface {
+	// AttachToContainer attaches to a container in the pod, copying data
+	// between in/out/err and the container's stdin/stdout/stderr.
+	AttachToContainer(name string, uid types.UID, container string, in io.Reader, out, err io.WriteCloser, tty bool, resize <-chan remotecommand.TerminalSize, timeout time.Duration) error
+}
+
+// ServeAttach handles requests to attach to a container. After
+// creating/receiving the required streams, it delegates the actual attachment
+// to the attacher.
+func ServeAttach(w http.ResponseWriter, req *http.Request, attacher Attacher, podName string, uid types.UID, container string, streamOpts *Options, idleTimeout, streamCreationTimeout time.Duration, supportedProtocols []string) {
+	ctx, ok := createStreams(req, w, streamOpts, supportedProtocols, idleTimeout, streamCreationTimeout)
+	if !ok {
+		// error is handled by createStreams
+		return
+	}
+	defer ctx.conn.Close()
+
+	err := attacher.AttachToContainer(podName, uid, container, ctx.stdinStream, ctx.stdoutStream, ctx.stderrStream, ctx.tty, ctx.resizeChan, 0)
+	if err != nil {
+		if exitErr, ok := err.(utilexec.ExitError); ok && exitErr.Exited() {
+			rc := exitErr.ExitStatus()
+			ctx.writeStatus(&apierrors.StatusError{ErrStatus: metav1.Status{
+				Status: metav1.StatusFailure,
+				Reason: remotecommandconsts.NonZeroExitCodeReason,
+				Details: &metav1.StatusDetails{
+					Causes: []metav1.StatusCause{
+						{
+							Type:    remotecommandconsts.ExitCodeCauseType,
+							Message: fmt.Sprintf("%d", rc),
+						},
+					},
+				},
+				Message: fmt.Sprintf("command terminated with non-zero exit code: %v", exitErr),
+			}})
+			return
+		}
+		err = fmt.Errorf("error attaching to container: %v", err)
+		runtime.HandleError(err)
+		ctx.writeStatus(apierrors.NewInternalError(err))
+		return
+	}
+	ctx.writeStatus(&apierrors.StatusError{ErrStatus: metav1.Status{
+		Status: metav1.StatusSuccess,
+	}})
+}

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())
 				},