oci-image-tool: implement create-runtime-bundle

Fixes opencontainers#99, opencontainers#87

Signed-off-by: Sergiusz Urbaniak <sur@coreos.com>

cmd/oci-image-tool/create_runtime_bundle.go

@@ -0,0 +1,109 @@
+// Copyright 2016 The Linux Foundation
+//
+// 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"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/opencontainers/image-spec/image"
+	"github.com/spf13/cobra"
+)
+
+// supported unpack types
+var bundleTypes = []string{
+	typeImageLayout,
+	typeImage,
+}
+
+type bundleCmd struct {
+	stdout *log.Logger
+	stderr *log.Logger
+	typ    string // the type to validate, can be empty string
+	ref    string
+	root   string
+}
+
+func newBundleCmd(stdout, stderr *log.Logger) *cobra.Command {
+	v := &bundleCmd{
+		stdout: stdout,
+		stderr: stderr,
+	}
+
+	cmd := &cobra.Command{
+		Use:   "create-runtime-bundle [src] [dest]",
+		Short: "Create an OCI image runtime bundle",
+		Long:  `Creates an OCI image runtime bundle at the destination directory [dest] from an OCI image present at [src].`,
+		Run:   v.Run,
+	}
+
+	cmd.Flags().StringVar(
+		&v.typ, "type", "",
+		fmt.Sprintf(
+			`Type of the file to unpack. If unset, oci-image-tool will try to auto-detect the type. One of "%s"`,
+			strings.Join(unpackTypes, ","),
+		),
+	)
+
+	cmd.Flags().StringVar(
+		&v.ref, "ref", "v1.0",
+		`The ref pointing to the manifest of the OCI image. This must be present in the "refs" subdirectory of the image.`,
+	)
+
+	cmd.Flags().StringVar(
+		&v.root, "rootfs", "rootfs",
+		`A directory representing the root filesystem of the container in the OCI runtime bundle.
+It is strongly recommended to keep the default value.`,
+	)
+
+	return cmd
+}
+
+func (v *bundleCmd) Run(cmd *cobra.Command, args []string) {
+	if len(args) != 2 {
+		v.stderr.Print("both src and dest must be provided")
+		if err := cmd.Usage(); err != nil {
+			v.stderr.Println(err)
+		}
+		os.Exit(1)
+	}
+
+	if v.typ == "" {
+		typ, err := autodetect(args[0])
+		if err != nil {
+			v.stderr.Printf("%q: autodetection failed: %v", args[0], err)
+			os.Exit(1)
+		}
+		v.typ = typ
+	}
+
+	var err error
+	switch v.typ {
+	case typeImageLayout:
+		err = image.CreateRuntimeBundleLayout(args[0], args[1], v.ref, v.root)
+
+	case typeImage:
+		err = image.CreateRuntimeBundle(args[0], args[1], v.ref, v.root)
+	}
+
+	if err != nil {
+		v.stderr.Printf("unpacking failed: %v", err)
+		os.Exit(1)
+	}
+
+	os.Exit(0)
+}

cmd/oci-image-tool/main.go

@@ -32,6 +32,7 @@ func main() {
 
 	cmd.AddCommand(newValidateCmd(stdout, stderr))
 	cmd.AddCommand(newUnpackCmd(stdout, stderr))
+	cmd.AddCommand(newBundleCmd(stdout, stderr))
 
 	if err := cmd.Execute(); err != nil {
 		stderr.Println(err)

image/config.go

@@ -0,0 +1,138 @@
+// Copyright 2016 The Linux Foundation
+//
+// 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 image
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/opencontainers/image-spec/schema"
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+type cfg struct {
+	User         string
+	Memory       int64
+	MemorySwap   int64
+	CpuShares    int64
+	ExposedPorts map[string]struct{}
+	Env          []string
+	Entrypoint   []string
+	Cmd          []string
+	Volumes      map[string]struct{}
+	WorkingDir   string
+}
+
+type config struct {
+	Architecture string `json:"architecture"`
+	OS           string `json:"os"`
+	Config       cfg    `json:"config"`
+}
+
+func findConfig(w walker, d *descriptor) (*config, error) {
+	var c config
+	cpath := filepath.Join("blobs", d.Digest)
+
+	f := func(path string, info os.FileInfo, r io.Reader) error {
+		if info.IsDir() {
+			return nil
+		}
+
+		if filepath.Clean(path) != cpath {
+			return nil
+		}
+
+		buf, err := ioutil.ReadAll(r)
+		if err != nil {
+			return errors.Wrapf(err, "%s: error reading config", path)
+		}
+
+		if err := schema.MediaTypeImageSerializationConfig.Validate(bytes.NewReader(buf)); err != nil {
+			return errors.Wrapf(err, "%s: config validation failed", path)
+		}
+
+		if err := json.Unmarshal(buf, &c); err != nil {
+			return err
+		}
+
+		return errEOW
+	}
+
+	switch err := w.walk(f); err {
+	case nil:
+		return nil, fmt.Errorf("%s: config not found", cpath)
+	case errEOW:
+		// found, continue below
+	default:
+		return nil, err
+	}
+
+	return &c, nil
+}
+
+func (c *config) runtimeSpec(rootfs string) specs.Spec {
+	var s specs.Spec
+	s.Version = "v0.5.0"
+	s.Root.Path = rootfs
+	s.Process.Cwd = c.Config.WorkingDir
+	s.Process.Env = append([]string(nil), c.Config.Env...)
+	s.Process.Args = append([]string(nil), c.Config.Entrypoint...)
+	s.Process.Args = append(s.Process.Args, c.Config.Cmd...)
+
+	if uid, err := strconv.Atoi(c.Config.User); err == nil {
+		s.Process.User.UID = uint32(uid)
+	}
+
+	if ug := strings.Split(c.Config.User, ":"); len(ug) == 2 {
+		if uid, err := strconv.Atoi(ug[0]); err == nil {
+			s.Process.User.UID = uint32(uid)
+		}
+
+		if gid, err := strconv.Atoi(ug[1]); err == nil {
+			s.Process.User.GID = uint32(gid)
+		}
+	}
+
+	s.Platform.OS = c.OS
+	s.Platform.Arch = c.Architecture
+
+	if c.OS == "linux" {
+		mem := uint64(c.Config.Memory)
+		swap := uint64(c.Config.MemorySwap)
+		shares := uint64(c.Config.CpuShares)
+
+		s.Linux.Resources = &specs.Resources{
+			CPU: &specs.CPU{
+				Shares: &shares,
+			},
+
+			Memory: &specs.Memory{
+				Limit:       &mem,
+				Reservation: &mem,
+				Swap:        &swap,
+			},
+		}
+	}
+
+	return s
+}

image/image.go

@@ -15,7 +15,9 @@
 package image
 
 import (
+	"encoding/json"
 	"os"
+	"path/filepath"
 
 	"github.com/pkg/errors"
 )
@@ -101,3 +103,62 @@ func unpack(w walker, dest, refName string) error {
 
 	return m.unpack(w, dest)
 }
+
+// CreateRuntimeBundleLayout walks through the file tree given given by src and
+// creates an OCI runtime bundle in the given destination dest
+// or returns an error if the unpacking failed.
+func CreateRuntimeBundleLayout(src, dest, ref, root string) error {
+	return createRuntimeBundle(newPathWalker(src), dest, ref, root)
+}
+
+// CreateRuntimeBundle walks through the given .tar file and
+// creates an OCI runtime bundle in the given destination dest
+// or returns an error if the unpacking failed.
+func CreateRuntimeBundle(tarFile, dest, ref, root string) error {
+	f, err := os.Open(tarFile)
+	if err != nil {
+		return errors.Wrap(err, "unable to open file")
+	}
+	defer f.Close()
+
+	return createRuntimeBundle(newTarWalker(f), dest, ref, root)
+}
+
+func createRuntimeBundle(w walker, dest, refName, rootfs string) error {
+	ref, err := findDescriptor(w, refName)
+	if err != nil {
+		return err
+	}
+
+	if err = ref.validate(w); err != nil {
+		return err
+	}
+
+	m, err := findManifest(w, ref)
+	if err != nil {
+		return err
+	}
+
+	if err = m.validate(w); err != nil {
+		return err
+	}
+
+	c, err := findConfig(w, &m.Config)
+	if err != nil {
+		return err
+	}
+
+	if err := m.unpack(w, filepath.Join(dest, rootfs)); err != nil {
+		return err
+	}
+
+	spec := c.runtimeSpec(rootfs)
+
+	f, err := os.Create(filepath.Join(dest, "config.json"))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return json.NewEncoder(f).Encode(spec)
+}