Add support for Attach API functionality (#1090)

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

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,
+	}})
+}