Support multi-container pod for "kubectl logs"

kubectl logs -l will print logs for pods with the same label, however
it doesn't support pods with multi containers. This change adds support
to it with --all-containers.

Ussage:
$ kubectl logs my-pod --all-containers
$ kubectl logs -laa=bb --all-containers
$ kubectl logs my-pod my-container --all-containers (err: --all-containers=true should not be specifiled with container name my-container)

pkg/kubectl/cmd/logs.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"math"
 	"os"
@@ -41,8 +42,11 @@ var (
 		# Return snapshot logs from pod nginx with only one container
 		kubectl logs nginx
 
-		# Return snapshot logs for the pods defined by label app=nginx
-		kubectl logs -lapp=nginx
+		# Return snapshot logs from pod nginx with multi containers
+		kubectl logs nginx --all-containers=true
+
+		# Return snapshot logs from all containers in pods defined by label app=nginx
+		kubectl logs -lapp=nginx --all-containers=true
 
 		# Return snapshot of previous terminated ruby container logs from pod web-1
 		kubectl logs -p -c ruby web-1
@@ -70,9 +74,10 @@ const (
 )
 
 type LogsOptions struct {
-	Namespace   string
-	ResourceArg string
-	Options     runtime.Object
+	Namespace     string
+	ResourceArg   string
+	AllContainers bool
+	Options       runtime.Object
 
 	Mapper  meta.RESTMapper
 	Typer   runtime.ObjectTyper
@@ -106,6 +111,7 @@ func NewCmdLogs(f cmdutil.Factory, out, errOut io.Writer) *cobra.Command {
 		},
 		Aliases: []string{"log"},
 	}
+	cmd.Flags().Bool("all-containers", false, "Get all containers's logs in the pod(s).")
 	cmd.Flags().BoolP("follow", "f", false, "Specify if the logs should be streamed.")
 	cmd.Flags().Bool("timestamps", false, "Include timestamps on each line in the log output")
 	cmd.Flags().Int64("limit-bytes", 0, "Maximum bytes of logs to return. Defaults to no limit.")
@@ -125,6 +131,7 @@ func NewCmdLogs(f cmdutil.Factory, out, errOut io.Writer) *cobra.Command {
 func (o *LogsOptions) Complete(f cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []string) error {
 	containerName := cmdutil.GetFlagString(cmd, "container")
 	selector := cmdutil.GetFlagString(cmd, "selector")
+	o.AllContainers = cmdutil.GetFlagBool(cmd, "all-containers")
 	switch len(args) {
 	case 0:
 		if len(selector) == 0 {
@@ -221,6 +228,9 @@ func (o LogsOptions) Validate() error {
 	if !ok {
 		return errors.New("unexpected logs options object")
 	}
+	if o.AllContainers && len(logsOptions.Container) > 0 {
+		return fmt.Errorf("--all-containers=true should not be specifiled with container name %s", logsOptions.Container)
+	}
 	if errs := validation.ValidatePodLogOptions(logsOptions); len(errs) > 0 {
 		return errs.ToAggregate()
 	}
@@ -233,16 +243,40 @@ func (o LogsOptions) RunLogs() error {
 	switch t := o.Object.(type) {
 	case *api.PodList:
 		for _, p := range t.Items {
-			if err := o.getLogs(&p); err != nil {
+			if err := o.getPodLogs(&p); err != nil {
 				return err
 			}
 		}
 		return nil
+	case *api.Pod:
+		return o.getPodLogs(t)
 	default:
 		return o.getLogs(o.Object)
 	}
 }
 
+// getPodLogs checks whether o.AllContainers is set to true.
+// If so, it retrives all containers' log in the pod.
+func (o LogsOptions) getPodLogs(pod *api.Pod) error {
+	if !o.AllContainers {
+		return o.getLogs(pod)
+	}
+
+	for _, c := range pod.Spec.InitContainers {
+		o.Options.(*api.PodLogOptions).Container = c.Name
+		if err := o.getLogs(pod); err != nil {
+			return err
+		}
+	}
+	for _, c := range pod.Spec.Containers {
+		o.Options.(*api.PodLogOptions).Container = c.Name
+		if err := o.getLogs(pod); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (o LogsOptions) getLogs(obj runtime.Object) error {
 	req, err := o.LogsForObject(obj, o.Options, o.GetPodTimeout)
 	if err != nil {

pkg/kubectl/cmd/logs_test.go

@@ -109,28 +109,39 @@ func TestValidateLogFlags(t *testing.T) {
 	tests := []struct {
 		name     string
 		flags    map[string]string
+		args     []string
 		expected string
 	}{
 		{
 			name:     "since & since-time",
 			flags:    map[string]string{"since": "1h", "since-time": "2006-01-02T15:04:05Z"},
+			args:     []string{"foo"},
 			expected: "at most one of `sinceTime` or `sinceSeconds` may be specified",
 		},
 		{
 			name:     "negative since-time",
 			flags:    map[string]string{"since": "-1s"},
+			args:     []string{"foo"},
 			expected: "must be greater than 0",
 		},
 		{
 			name:     "negative limit-bytes",
 			flags:    map[string]string{"limit-bytes": "-100"},
+			args:     []string{"foo"},
 			expected: "must be greater than 0",
 		},
 		{
 			name:     "negative tail",
 			flags:    map[string]string{"tail": "-100"},
+			args:     []string{"foo"},
 			expected: "must be greater than or equal to 0",
 		},
+		{
+			name:     "container name combined with --all-containers",
+			flags:    map[string]string{"all-containers": "true"},
+			args:     []string{"my-pod", "my-container"},
+			expected: "--all-containers=true should not be specifiled with container",
+		},
 	}
 	for _, test := range tests {
 		buf := bytes.NewBuffer([]byte{})
@@ -146,7 +157,7 @@ func TestValidateLogFlags(t *testing.T) {
 			o.Complete(f, os.Stdout, cmd, args)
 			out = o.Validate().Error()
 		}
-		cmd.Run(cmd, []string{"foo"})
+		cmd.Run(cmd, test.args)
 
 		if !strings.Contains(out, test.expected) {
 			t.Errorf("%s: expected to find:\n\t%s\nfound:\n\t%s\n", test.name, test.expected, out)