mirror of https://github.com/k3s-io/k3s
contrib: add go2docker
Johan Euphrosine
parent
7603f88960
commit
e7c4772d27
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@ -0,0 +1,35 @@
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# go2docker
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## Description
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`go2docker` is a command line tool to create minimal docker images from
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`SCRATCH` for go packages.
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It is based on the [Docker Image Specification v1.0.0](https://github.com/docker/docker/blob/master/image/spec/v1.md).
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l
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## Usage
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```
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go2docker [-image NAMESPACE/BASENAME] [PACKAGES]
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```
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### Options
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- `image`: namespace/name for the repository, default to go2docker/$(basename)
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### Examples
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```
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$ go get -d github.com/golang/example/hello
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$ go2docker -image golang/hello github.com/golang/example/hello | docker load
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$ docker images | grep hello
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golang/hello latest e96b9f048cdf 2 seconds ago 1.477 MB
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$ docker run golang/hello
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Hello, Go examples!
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```
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## TODOs
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- [ ] add command line flag for entrypoint
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- [ ] add command line flag for exposed port
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- [ ] add command line flag for volume
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- [ ] go get the package if not present in `$GOPATH`
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- [ ] add push command
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- [ ] test more complicated package (ex: etcd)
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- [ ] fix permission inside the tar
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@ -0,0 +1,167 @@
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// The go2docker command compiles a go main package and forge a minimal
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// docker image from the resulting static binary.
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//
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// usage: go2docker [-image namespace/basename] go/pkg/path | docker load
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package main
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import (
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"archive/tar"
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"bytes"
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"crypto/rand"
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"encoding/hex"
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"encoding/json"
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"flag"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path"
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"path/filepath"
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"strings"
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"time"
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)
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type Config struct {
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Cmd []string `json:"Cmd"`
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}
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type Image struct {
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ID string `json:"id"`
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Created time.Time `json:"created"`
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DockerVersion string `json:"docker_version"`
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Config Config `json:"config"`
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Architecture string `json:"architecture"`
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OS string `json:"os"`
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}
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var image = flag.String("image", "", "namespace/name for the repository, default to go2docker/$(basename)")
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const (
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DockerVersion = "1.4.0"
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Arch = "amd64"
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OS = "linux"
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Version = "1.0"
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Namespace = "go2docker"
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)
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func main() {
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flag.Parse()
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args := []string{"."}
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if flag.NArg() > 0 {
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args = flag.Args()
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}
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fpath, err := filepath.Abs(args[0])
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ext := filepath.Ext(fpath)
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basename := filepath.Base(fpath[:len(fpath)-len(ext)])
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if *image == "" {
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if err != nil {
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log.Fatalf("failed to get absolute path: %v", err)
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}
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*image = path.Join(Namespace, basename)
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}
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tmpDir, err := ioutil.TempDir("", "")
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if err != nil {
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log.Fatalf("failed to create temp directory: %v", err)
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}
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aout := filepath.Join(tmpDir, basename)
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command := append([]string{"go", "build", "-o", aout, "-a", "-tags", "netgo", "-ldflags", "'-w'"}, args...)
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if _, err := exec.Command(command[0], command[1:]...).Output(); err != nil {
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log.Fatalf("failed to run command %q: %v", strings.Join(command, " "), err)
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}
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imageIDBytes := make([]byte, 32)
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if _, err := rand.Read(imageIDBytes); err != nil {
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log.Fatalf("failed to generate ID: %v")
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}
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imageID := hex.EncodeToString(imageIDBytes)
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repo := map[string]map[string]string{
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*image: map[string]string{
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"latest": imageID,
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},
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}
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repoJSON, err := json.Marshal(repo)
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if err != nil {
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log.Fatalf("failed to serialize repo %#v: %v", repo, err)
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}
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tw := tar.NewWriter(os.Stdout)
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if err := tw.WriteHeader(&tar.Header{
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Name: "repositories",
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Size: int64(len(repoJSON)),
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}); err != nil {
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log.Fatalf("failed to write /repository header: %v", err)
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}
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if _, err := tw.Write(repoJSON); err != nil {
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log.Fatalf(" failed to write /repository body: %v", err)
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}
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if err := tw.WriteHeader(&tar.Header{
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Name: imageID + "/VERSION",
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Size: int64(len(Version)),
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}); err != nil {
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log.Fatalf("failed to write /%s/VERSION header: %v", imageID, err)
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}
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if _, err := tw.Write([]byte(Version)); err != nil {
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log.Fatalf(" failed to write /%s/VERSION body: %v", imageID, err)
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}
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imageJSON, err := json.Marshal(Image{
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ID: imageID,
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Created: time.Now().UTC(),
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DockerVersion: Version,
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Config: Config{
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Cmd: []string{"/" + basename},
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},
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Architecture: Arch,
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OS: OS,
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})
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if err := tw.WriteHeader(&tar.Header{
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Name: imageID + "/json",
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Size: int64(len(imageJSON)),
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}); err != nil {
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log.Fatalf("failed to write /%s/json header: %v", imageID, err)
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}
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if _, err := tw.Write(imageJSON); err != nil {
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log.Fatalf("failed to write /%s/json body: %v", imageID, err)
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}
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var buf bytes.Buffer
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ftw := tar.NewWriter(&buf)
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file, err := os.Open(aout)
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if err != nil {
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log.Fatalf("failed to open %q: %v", aout, err)
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}
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finfo, err := file.Stat()
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if err != nil {
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log.Fatalf("failed to get file info %q: %v", aout, err)
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}
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fheader, err := tar.FileInfoHeader(finfo, "")
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if err != nil {
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log.Fatalf("failed to get file info header %q: %v", aout, err)
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}
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fheader.Name = basename
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if err := ftw.WriteHeader(fheader); err != nil {
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log.Fatalf("failed to write /%s header: %v", aout, err)
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}
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if _, err := io.Copy(ftw, file); err != nil {
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log.Fatalf("failed to write /%s body: %v", aout, err)
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}
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if err := ftw.Close(); err != nil {
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log.Fatalf("failed to close layer.tar: %v", err)
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}
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layerBytes := buf.Bytes()
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if err := tw.WriteHeader(&tar.Header{
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Name: imageID + "/layer.tar",
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Size: int64(len(layerBytes)),
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}); err != nil {
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log.Fatalf("failed to write /%s/layer.tar header: %v", imageID, err)
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}
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if _, err := tw.Write(layerBytes); err != nil {
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log.Fatalf("failed to write /%s/layer.tar body: %v", imageID, err)
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}
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if err := tw.Close(); err != nil {
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log.Fatalf("failed to close image.tar: %v", err)
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}
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}
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