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|
// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
//go:build !plan9
// The sync-containers command synchronizes container image tags from one
// registry to another.
//
// It is intended as a workaround for ghcr.io's lack of good push credentials:
// you can either authorize "classic" Personal Access Tokens in your org (which
// are a common vector of very bad compromise), or you can get a short-lived
// credential in a Github action.
//
// Since we publish to both Docker Hub and ghcr.io, we use this program in a
// Github action to effectively rsync from docker hub into ghcr.io, so that we
// can continue to forbid dangerous Personal Access Tokens in the tailscale org.
package main
import (
"context"
"flag"
"fmt"
"log"
"sort"
"strings"
"github.com/google/go-containerregistry/pkg/authn"
"github.com/google/go-containerregistry/pkg/authn/github"
"github.com/google/go-containerregistry/pkg/name"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/remote"
"github.com/google/go-containerregistry/pkg/v1/types"
)
var (
src = flag.String("src", "", "Source image")
dst = flag.String("dst", "", "Destination image")
max = flag.Int("max", 0, "Maximum number of tags to sync (0 for all tags)")
dryRun = flag.Bool("dry-run", true, "Don't actually sync anything")
)
func main() {
flag.Parse()
if *src == "" {
log.Fatalf("--src is required")
}
if *dst == "" {
log.Fatalf("--dst is required")
}
keychain := authn.NewMultiKeychain(authn.DefaultKeychain, github.Keychain)
opts := []remote.Option{
remote.WithAuthFromKeychain(keychain),
remote.WithContext(context.Background()),
}
stags, err := listTags(*src, opts...)
if err != nil {
log.Fatalf("listing source tags: %v", err)
}
dtags, err := listTags(*dst, opts...)
if err != nil {
log.Fatalf("listing destination tags: %v", err)
}
add, remove := diffTags(stags, dtags)
if ln := len(add); ln > 0 {
log.Printf("%d tags to push: %s", len(add), strings.Join(add, ", "))
if *max > 0 && ln > *max {
log.Printf("Limiting sync to %d tags", *max)
add = add[:*max]
}
}
for _, tag := range add {
if !*dryRun {
log.Printf("Syncing tag %q", tag)
if err := copyTag(*src, *dst, tag, opts...); err != nil {
log.Printf("Syncing tag %q: progress error: %v", tag, err)
}
} else {
log.Printf("Dry run: would sync tag %q", tag)
}
}
if len(remove) > 0 {
log.Printf("%d tags to remove: %s\n", len(remove), strings.Join(remove, ", "))
log.Printf("Not removing any tags for safety.\n")
}
var wellKnown = [...]string{"latest", "stable"}
for _, tag := range wellKnown {
if needsUpdate(*src, *dst, tag) {
if err := copyTag(*src, *dst, tag, opts...); err != nil {
log.Printf("Updating tag %q: progress error: %v", tag, err)
}
}
}
}
func copyTag(srcStr, dstStr, tag string, opts ...remote.Option) error {
src, err := name.ParseReference(fmt.Sprintf("%s:%s", srcStr, tag))
if err != nil {
return err
}
dst, err := name.ParseReference(fmt.Sprintf("%s:%s", dstStr, tag))
if err != nil {
return err
}
desc, err := remote.Get(src)
if err != nil {
return err
}
ch := make(chan v1.Update, 10)
opts = append(opts, remote.WithProgress(ch))
progressDone := make(chan struct{})
go func() {
defer close(progressDone)
for p := range ch {
fmt.Printf("Syncing tag %q: %d%% (%d/%d)\n", tag, int(float64(p.Complete)/float64(p.Total)*100), p.Complete, p.Total)
if p.Error != nil {
fmt.Printf("error: %v\n", p.Error)
}
}
}()
switch desc.MediaType {
case types.OCIManifestSchema1, types.DockerManifestSchema2:
img, err := desc.Image()
if err != nil {
return err
}
if err := remote.Write(dst, img, opts...); err != nil {
return err
}
case types.OCIImageIndex, types.DockerManifestList:
idx, err := desc.ImageIndex()
if err != nil {
return err
}
if err := remote.WriteIndex(dst, idx, opts...); err != nil {
return err
}
}
<-progressDone
return nil
}
func listTags(repoStr string, opts ...remote.Option) ([]string, error) {
repo, err := name.NewRepository(repoStr)
if err != nil {
return nil, err
}
tags, err := remote.List(repo, opts...)
if err != nil {
return nil, err
}
sort.Strings(tags)
return tags, nil
}
func diffTags(src, dst []string) (add, remove []string) {
srcd := make(map[string]bool)
for _, tag := range src {
srcd[tag] = true
}
dstd := make(map[string]bool)
for _, tag := range dst {
dstd[tag] = true
}
for _, tag := range src {
if !dstd[tag] {
add = append(add, tag)
}
}
for _, tag := range dst {
if !srcd[tag] {
remove = append(remove, tag)
}
}
sort.Strings(add)
sort.Strings(remove)
return add, remove
}
func needsUpdate(srcStr, dstStr, tag string) bool {
src, err := name.ParseReference(fmt.Sprintf("%s:%s", srcStr, tag))
if err != nil {
return false
}
dst, err := name.ParseReference(fmt.Sprintf("%s:%s", dstStr, tag))
if err != nil {
return false
}
srcDesc, err := remote.Get(src)
if err != nil {
return false
}
dstDesc, err := remote.Get(dst)
if err != nil {
return true
}
return srcDesc.Digest != dstDesc.Digest
}
|
