build.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"

	"github.com/sgotti/acido/util"

	"github.com/sgotti/acido/Godeps/_workspace/src/github.com/coreos/fleet/log"
	"github.com/sgotti/acido/Godeps/_workspace/src/github.com/coreos/rocket/cas"
	"github.com/sgotti/acido/Godeps/_workspace/src/github.com/coreos/rocket/pkg/aci"
	"github.com/sgotti/acido/Godeps/_workspace/src/github.com/sgotti/acibuilder"
)

var (
	buildImageManifest string
	buildBaseImageHash string
	buildOverwrite     bool

	cmdBuild = &Command{
		Name:        "build",
		Summary:     "Build a previously prepared image with only the differences from a base and the new image",
		Usage:       "[--overwrite] IMAGEFS OUTPUTFILE",
		Description: `IMAGEFS is the directory containing the image data.`,
		Run:         runBuild,
	}
)

func init() {
	cmdBuild.Flags.BoolVar(&buildOverwrite, "overwrite", false, "Overwrite target file if it already exists")
	commands = append(commands, cmdBuild)
}

func build(args []string) error {
	if len(args) != 2 {
		return fmt.Errorf("must provide imagefs and output file")
	}

	ds, err := cas.NewStore(globalFlags.Dir)
	if err != nil {
		return err
	}

	imagefs := args[0]
	out := args[1]
	log.Infof("out file: %s", out)
	tmpdir, err := ioutil.TempDir(globalFlags.WorkDir, "")
	if err != nil {
		return err
	}
	log.Debugf("tmpdir: %s", tmpdir)
	os.Mkdir(filepath.Join(tmpdir, "/rootfs"), 0755)

	im, err := util.LoadImageManifest(filepath.Join(imagefs, "manifest"))
	if err != nil {
		return err
	}
	dependencies := im.Dependencies
	var aciBuilder acibuilder.ACIBuilder
	switch s := len(dependencies); {
	case s > 1:
		return fmt.Errorf("exactly one dependency is required")
	case s == 1:
		dependency := dependencies[0]
		log.Debugf("Dependency ImageID: %s\n", dependency.ImageID)
		if !dependency.ImageID.Empty() {
			err := aci.RenderACIWithImageID(*dependency.ImageID, tmpdir, ds)
			if err != nil {
				return err
			}

		}
		aciBuilder = acibuilder.NewDiffACIBuilder(filepath.Join(tmpdir, "rootfs"), filepath.Join(imagefs, "rootfs"))
	case s == 0:
		aciBuilder = acibuilder.NewSimpleACIBuilder(filepath.Join(imagefs, "rootfs"))
	}

	mode := os.O_CREATE | os.O_WRONLY
	if buildOverwrite {
		mode |= os.O_TRUNC
	} else {
		mode |= os.O_EXCL
	}
	fh, err := os.OpenFile(out, mode, 0644)
	if err != nil {
		if os.IsExist(err) {
			return fmt.Errorf("target file exists (try --overwrite)")
		} else {
			return fmt.Errorf("build: Unable to open target %s: %v", out, err)
		}
	}
	defer func() {
		fh.Close()
	}()

	err = aciBuilder.Build(*im, fh)
	if err != nil {
		return err
	}

	return nil
}

func runBuild(args []string) (exit int) {
	err := build(args)
	if err != nil {
		log.Errorf("error: %v", err)
		return 1
	}
	return 0
}