cli: implement ps command

ps command is used by ```docker top``` to show
the processes running inside the container

partially fixes #95

Signed-off-by: Julio Montes <julio.montes@intel.com>

main.go

@@ -109,6 +109,7 @@ var runtimeCommands = []cli.Command{
 	killCLICommand,
 	listCLICommand,
 	pauseCLICommand,
+	psCLICommand,
 	resumeCLICommand,
 	runCLICommand,
 	startCLICommand,

ps.go

@@ -0,0 +1,90 @@
+// Copyright (c) 2014,2015,2016 Docker, Inc.
+// Copyright (c) 2017 Intel Corporation
+//
+// 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 main
+
+import (
+	"fmt"
+
+	vc "github.com/containers/virtcontainers"
+	"github.com/urfave/cli"
+)
+
+var psCLICommand = cli.Command{
+	Name:      "ps",
+	Usage:     "ps displays the processes running inside a container",
+	ArgsUsage: `<container-id> [ps options]`,
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "format, f",
+			Value: "table",
+			Usage: `select one of: ` + formatOptions,
+		},
+	},
+	Action: func(context *cli.Context) error {
+		if context.Args().Present() == false {
+			return fmt.Errorf("Missing container ID, should at least provide one")
+		}
+
+		var args []string
+		if len(context.Args()) > 1 {
+			args = context.Args()[1:]
+		}
+
+		return ps(context.Args().First(), context.String("format"), args)
+	},
+	SkipArgReorder: true,
+}
+
+func ps(containerID, format string, args []string) error {
+	if containerID == "" {
+		return fmt.Errorf("Missing container ID")
+	}
+
+	// Checks the MUST and MUST NOT from OCI runtime specification
+	status, podID, err := getExistingContainerInfo(containerID)
+	if err != nil {
+		return err
+	}
+
+	containerID = status.ID
+
+	// container MUST be running
+	if status.State.State != vc.StateRunning {
+		return fmt.Errorf("Container %s is not running", containerID)
+	}
+
+	var options vc.ProcessListOptions
+
+	// [1:] is to remove command name, ex:
+	// context.Args(): [containet_id ps_arg1 ps_arg2 ...]
+	// psArgs:         [ps_arg1 ps_arg2 ...]
+	//
+	options.Args = args
+	if len(options.Args) == 0 {
+		options.Args = []string{"-ef"}
+	}
+
+	options.Format = format
+
+	msg, err := vci.ProcessListContainer(containerID, podID, options)
+	if err != nil {
+		return err
+	}
+
+	fmt.Print(string(msg))
+
+	return nil
+}

ps_test.go

@@ -0,0 +1,134 @@
+// Copyright (c) 2017 Intel Corporation
+//
+// 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 main
+
+import (
+	"flag"
+	"testing"
+
+	vc "github.com/containers/virtcontainers"
+	"github.com/containers/virtcontainers/pkg/oci"
+	"github.com/containers/virtcontainers/pkg/vcMock"
+	"github.com/stretchr/testify/assert"
+	"github.com/urfave/cli"
+)
+
+func TestPSCLIAction(t *testing.T) {
+	assert := assert.New(t)
+
+	flagSet := flag.NewFlagSet("flag", flag.ContinueOnError)
+	flagSet.Parse([]string{"cc-runtime"})
+
+	// create a new fake context
+	ctx := cli.NewContext(&cli.App{Metadata: map[string]interface{}{}}, flagSet, nil)
+
+	// get Action function
+	actionFunc, ok := psCLICommand.Action.(func(ctx *cli.Context) error)
+	assert.True(ok)
+
+	err := actionFunc(ctx)
+	assert.Error(err, "Missing container ID")
+}
+
+func TestPSFailure(t *testing.T) {
+	assert := assert.New(t)
+
+	pod := &vcMock.Pod{
+		MockID: testContainerID,
+	}
+
+	pod.MockContainers = []*vcMock.Container{
+		{
+			MockID:  pod.ID(),
+			MockPod: pod,
+		},
+	}
+
+	testingImpl.ListPodFunc = func() ([]vc.PodStatus, error) {
+		// return a podStatus with the container status
+		return []vc.PodStatus{
+			{
+				ID: pod.ID(),
+				ContainersStatus: []vc.ContainerStatus{
+					{
+						ID: pod.ID(),
+						Annotations: map[string]string{
+							oci.ContainerTypeKey: string(vc.PodContainer),
+						},
+					},
+				},
+			},
+		}, nil
+	}
+
+	defer func() {
+		testingImpl.ListPodFunc = nil
+	}()
+
+	// inexistent container
+	err := ps("xyz123abc", "json", []string{"-ef"})
+	assert.Error(err)
+
+	// container is not running
+	err = ps(pod.ID(), "json", []string{"-ef"})
+	assert.Error(err)
+}
+
+func TestPSSuccessful(t *testing.T) {
+	assert := assert.New(t)
+
+	pod := &vcMock.Pod{
+		MockID: testContainerID,
+	}
+
+	pod.MockContainers = []*vcMock.Container{
+		{
+			MockID:  pod.ID(),
+			MockPod: pod,
+		},
+	}
+
+	testingImpl.ListPodFunc = func() ([]vc.PodStatus, error) {
+		// return a podStatus with the container status
+		return []vc.PodStatus{
+			{
+				ID: pod.ID(),
+				ContainersStatus: []vc.ContainerStatus{
+					{
+						State: vc.State{
+							State: vc.StateRunning,
+						},
+						ID: pod.ID(),
+						Annotations: map[string]string{
+							oci.ContainerTypeKey: string(vc.PodContainer),
+						},
+					},
+				},
+			},
+		}, nil
+	}
+
+	testingImpl.ProcessListContainerFunc = func(podID, containerID string, options vc.ProcessListOptions) (vc.ProcessList, error) {
+		return []byte("echo,sleep,grep"), nil
+	}
+
+	defer func() {
+		testingImpl.ListPodFunc = nil
+		testingImpl.ProcessListContainerFunc = nil
+	}()
+
+	err := ps(pod.ID(), "json", []string{})
+	assert.NoError(err)
+}