Merge pull request clearcontainers#196 from caoruidong/add-spec

cli: implement spec command

cli/main.go

@@ -119,6 +119,7 @@ var runtimeCommands = []cli.Command{
 	psCLICommand,
 	resumeCLICommand,
 	runCLICommand,
+	specCLICommand,
 	startCLICommand,
 	stateCLICommand,
 	versionCLICommand,

cli/spec.go

@@ -0,0 +1,105 @@
+// Copyright (c) 2014,2015,2016,2017 Docker, Inc.
+// Copyright (c) 2018 Huawei Corporation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/opencontainers/runc/libcontainer/specconv"
+	"github.com/urfave/cli"
+)
+
+var specCLICommand = cli.Command{
+	Name:      "spec",
+	Usage:     "create a new specification file",
+	ArgsUsage: "",
+	Description: `The spec command creates the new specification file named "` + specConfig + `" for
+the bundle.
+
+The spec generated is just a starter file. Editing of the spec is required to
+achieve desired results. For example, the newly generated spec includes an args
+parameter that is initially set to call the "sh" command when the container is
+started. Calling "sh" may work for an ubuntu container or busybox, but will not
+work for containers that do not include the "sh" program.
+
+EXAMPLE:
+  To run docker's hello-world container one needs to set the args parameter
+in the spec to call hello. This can be done using the sed command or a text
+editor. The following commands create a bundle for hello-world, change the
+default args parameter in the spec from "sh" to "/hello", then run the hello
+command in a new hello-world container named container1:
+
+    mkdir hello
+    cd hello
+    docker pull hello-world
+    docker export $(docker create hello-world) > hello-world.tar
+    mkdir rootfs
+    tar -C rootfs -xf hello-world.tar
+    kata-runtime spec
+    sed -i 's;"sh";"/hello";' ` + specConfig + `
+    kata-runtime run container1
+
+In the run command above, "container1" is the name for the instance of the
+container that you are starting. The name you provide for the container instance
+must be unique on your host.
+
+An alternative for generating a customized spec config is to use "oci-runtime-tool", the
+sub-command "oci-runtime-tool generate" has lots of options that can be used to do any
+customizations as you want, see runtime-tools (https://github.com/opencontainers/runtime-tools)
+to get more information.
+
+When starting a container through kata-runtime, kata-runtime needs root privilege. If not
+already running as root, you can use sudo to give kata-runtime root privilege. For
+example: "sudo kata-runtime start container1" will give kata-runtime root privilege to start the
+container on your host.
+
+Alternatively, you can start a rootless container, which has the ability to run
+without root privileges. For this to work, the specification file needs to be
+adjusted accordingly. You can pass the parameter --rootless to this command to
+generate a proper rootless spec file.`,
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "bundle, b",
+			Value: "",
+			Usage: "path to the root of the bundle directory",
+		},
+	},
+	Action: func(context *cli.Context) error {
+		spec := specconv.Example()
+
+		checkNoFile := func(name string) error {
+			_, err := os.Stat(name)
+			if err == nil {
+				return fmt.Errorf("File %s exists. Remove it first", name)
+			}
+			if !os.IsNotExist(err) {
+				return err
+			}
+			return nil
+		}
+		bundle := context.String("bundle")
+		if bundle != "" {
+			if err := os.Chdir(bundle); err != nil {
+				return err
+			}
+		}
+		if err := checkNoFile(specConfig); err != nil {
+			return err
+		}
+		data, err := json.MarshalIndent(spec, "", "\t")
+		if err != nil {
+			return err
+		}
+		if err := ioutil.WriteFile(specConfig, data, 0640); err != nil {
+			return err
+		}
+		return nil
+	},
+}

cli/spec_test.go

@@ -0,0 +1,35 @@
+// Copyright (c) 2018 Huawei Corporation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package main
+
+import (
+	"flag"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/urfave/cli"
+)
+
+func TestSpecCliAction(t *testing.T) {
+	assert := assert.New(t)
+
+	actionFunc, ok := specCLICommand.Action.(func(context *cli.Context) error)
+	assert.True(ok)
+
+	flagSet := flag.NewFlagSet("flag", flag.ContinueOnError)
+	ctx := cli.NewContext(&cli.App{}, flagSet, nil)
+	defer os.Remove(specConfig)
+	err := actionFunc(ctx)
+	assert.NoError(err)
+
+	pattern := "gid=5"
+	patternRootless := "uidMappings"
+	err = grep(pattern, specConfig)
+	assert.NoError(err)
+	err = grep(patternRootless, specConfig)
+	assert.Error(err)
+}