Merge pull request #3956 from proppy/go2docker

contrib: add go2docker

contrib/go2docker/README.md

@@ -0,0 +1,35 @@
+# go2docker
+
+## Description
+
+`go2docker` is a command line tool to create minimal docker images from
+`SCRATCH` for go packages.
+
+It is based on the [Docker Image Specification v1.0.0](https://github.com/docker/docker/blob/master/image/spec/v1.md).
+l
+## Usage
+```
+go2docker [-image NAMESPACE/BASENAME] [PACKAGES]
+```
+
+### Options
+- `image`: namespace/name for the repository, default to go2docker/$(basename)
+
+### Examples
+```
+$ go get -d github.com/golang/example/hello
+$ go2docker -image golang/hello github.com/golang/example/hello | docker load
+$ docker images | grep hello
+golang/hello	   latest	e96b9f048cdf			2 seconds ago	1.477 MB
+$ docker run golang/hello
+Hello, Go examples!
+```
+
+## TODOs
+- [ ] add command line flag for entrypoint
+- [ ] add command line flag for exposed port
+- [ ] add command line flag for volume
+- [ ] go get the package if not present in `$GOPATH`
+- [ ] add push command
+- [ ] test more complicated package (ex: etcd)
+- [ ] fix permission inside the tar

contrib/go2docker/go2docker.go

@@ -0,0 +1,179 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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.
+*/
+
+// The go2docker command compiles a go main package and forge a minimal
+// docker image from the resulting static binary.
+//
+// usage: go2docker [-image namespace/basename] go/pkg/path | docker load
+package main
+
+import (
+	"archive/tar"
+	"bytes"
+	"crypto/rand"
+	"encoding/hex"
+	"encoding/json"
+	"flag"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+type Config struct {
+	Cmd []string `json:"Cmd"`
+}
+
+type Image struct {
+	ID            string    `json:"id"`
+	Created       time.Time `json:"created"`
+	DockerVersion string    `json:"docker_version"`
+	Config        Config    `json:"config"`
+	Architecture  string    `json:"architecture"`
+	OS            string    `json:"os"`
+}
+
+var image = flag.String("image", "", "namespace/name for the repository, default to go2docker/$(basename)")
+
+const (
+	DockerVersion = "1.4.0"
+	Arch          = "amd64"
+	OS            = "linux"
+	Version       = "1.0"
+	Namespace     = "go2docker"
+)
+
+func main() {
+	flag.Parse()
+	args := []string{"."}
+	if flag.NArg() > 0 {
+		args = flag.Args()
+	}
+
+	fpath, err := filepath.Abs(args[0])
+	ext := filepath.Ext(fpath)
+	basename := filepath.Base(fpath[:len(fpath)-len(ext)])
+
+	if *image == "" {
+		if err != nil {
+			log.Fatalf("failed to get absolute path: %v", err)
+		}
+		*image = path.Join(Namespace, basename)
+	}
+	tmpDir, err := ioutil.TempDir("", "")
+	if err != nil {
+		log.Fatalf("failed to create temp directory: %v", err)
+	}
+	aout := filepath.Join(tmpDir, basename)
+	command := append([]string{"go", "build", "-o", aout, "-a", "-tags", "netgo", "-installsuffix", "netgo"}, args...)
+	if _, err := exec.Command(command[0], command[1:]...).Output(); err != nil {
+		log.Fatalf("failed to run command %q: %v", strings.Join(command, " "), err)
+	}
+	imageIDBytes := make([]byte, 32)
+	if _, err := rand.Read(imageIDBytes); err != nil {
+		log.Fatalf("failed to generate ID: %v")
+	}
+	imageID := hex.EncodeToString(imageIDBytes)
+	repo := map[string]map[string]string{
+		*image: {
+			"latest": imageID,
+		},
+	}
+	repoJSON, err := json.Marshal(repo)
+	if err != nil {
+		log.Fatalf("failed to serialize repo %#v: %v", repo, err)
+	}
+	tw := tar.NewWriter(os.Stdout)
+	if err := tw.WriteHeader(&tar.Header{
+		Name: "repositories",
+		Size: int64(len(repoJSON)),
+	}); err != nil {
+		log.Fatalf("failed to write /repository header: %v", err)
+	}
+	if _, err := tw.Write(repoJSON); err != nil {
+		log.Fatalf(" failed to write /repository body: %v", err)
+	}
+	if err := tw.WriteHeader(&tar.Header{
+		Name: imageID + "/VERSION",
+		Size: int64(len(Version)),
+	}); err != nil {
+		log.Fatalf("failed to write /%s/VERSION header: %v", imageID, err)
+	}
+	if _, err := tw.Write([]byte(Version)); err != nil {
+		log.Fatalf(" failed to write /%s/VERSION body: %v", imageID, err)
+	}
+	imageJSON, err := json.Marshal(Image{
+		ID:            imageID,
+		Created:       time.Now().UTC(),
+		DockerVersion: Version,
+		Config: Config{
+			Cmd: []string{"/" + basename},
+		},
+		Architecture: Arch,
+		OS:           OS,
+	})
+	if err := tw.WriteHeader(&tar.Header{
+		Name: imageID + "/json",
+		Size: int64(len(imageJSON)),
+	}); err != nil {
+		log.Fatalf("failed to write /%s/json header: %v", imageID, err)
+	}
+	if _, err := tw.Write(imageJSON); err != nil {
+		log.Fatalf("failed to write /%s/json body: %v", imageID, err)
+	}
+	var buf bytes.Buffer
+	ftw := tar.NewWriter(&buf)
+	file, err := os.Open(aout)
+	if err != nil {
+		log.Fatalf("failed to open %q: %v", aout, err)
+	}
+	finfo, err := file.Stat()
+	if err != nil {
+		log.Fatalf("failed to get file info %q: %v", aout, err)
+	}
+	fheader, err := tar.FileInfoHeader(finfo, "")
+	if err != nil {
+		log.Fatalf("failed to get file info header %q: %v", aout, err)
+	}
+	fheader.Name = basename
+	if err := ftw.WriteHeader(fheader); err != nil {
+		log.Fatalf("failed to write /%s header: %v", aout, err)
+	}
+	if _, err := io.Copy(ftw, file); err != nil {
+		log.Fatalf("failed to write /%s body: %v", aout, err)
+	}
+	if err := ftw.Close(); err != nil {
+		log.Fatalf("failed to close layer.tar: %v", err)
+	}
+	layerBytes := buf.Bytes()
+	if err := tw.WriteHeader(&tar.Header{
+		Name: imageID + "/layer.tar",
+		Size: int64(len(layerBytes)),
+	}); err != nil {
+		log.Fatalf("failed to write /%s/layer.tar header: %v", imageID, err)
+	}
+	if _, err := tw.Write(layerBytes); err != nil {
+		log.Fatalf("failed to write /%s/layer.tar body: %v", imageID, err)
+	}
+	if err := tw.Close(); err != nil {
+		log.Fatalf("failed to close image.tar: %v", err)
+	}
+}