spec.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"runtime"

	"github.com/codegangsta/cli"
	"github.com/opencontainers/runtime-spec/specs-go"
)

var specCommand = cli.Command{
	Name:  "spec",
	Usage: "create a new specification file",
	Flags: []cli.Flag{
		cli.StringFlag{
			Name:  "bundle, b",
			Usage: "path to the root of the bundle directory",
		},
	},
	Action: func(context *cli.Context) {
		spec := specs.Spec{
			Version: specs.Version,
			Platform: specs.Platform{
				OS:   runtime.GOOS,
				Arch: runtime.GOARCH,
			},
			Root: specs.Root{
				Path:     "rootfs",
				Readonly: true,
			},
			Process: specs.Process{
				Terminal: true,
				User:     specs.User{},
				Args: []string{
					"sh",
				},
				Env: []string{
					"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
					"TERM=xterm",
				},
			},
			Hostname: "shell",
			Linux: specs.Linux{
				Resources: &specs.Resources{},
			},
		}

		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 {
				fmt.Printf("Failed to chdir to bundle dir:%s\nerror:%v\n", bundle, err)
				return
			}
		}
		if err := checkNoFile(specConfig); err != nil {
			fmt.Printf("%s\n", err.Error())
			return
		}
		data, err := json.MarshalIndent(&spec, "", "\t")
		if err != nil {
			fmt.Printf("%s\n", err.Error())
			return
		}
		if err := ioutil.WriteFile(specConfig, data, 0666); err != nil {
			fmt.Printf("%s\n", err.Error())
			return
		}
	},
}

func loadSpec(ocffile string) (*specs.Spec, error) {
	var spec specs.Spec

	if _, err := os.Stat(ocffile); os.IsNotExist(err) {
		return nil, fmt.Errorf("Please make sure bundle directory contains config.json: %v\n", err.Error())
	}

	ocfData, err := ioutil.ReadFile(ocffile)
	if err != nil {
		return nil, err
	}

	if err := json.Unmarshal(ocfData, &spec); err != nil {
		return nil, err
	}
	return &spec, nil
}