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client.go
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client.go
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package registryclient
import (
"fmt"
"net"
"net/http"
"net/url"
"path"
"sort"
"sync"
"time"
"github.com/golang/glog"
gocontext "golang.org/x/net/context"
"github.com/docker/distribution"
"github.com/docker/distribution/context"
"github.com/docker/distribution/reference"
registryclient "github.com/docker/distribution/registry/client"
"github.com/docker/distribution/registry/client/auth"
"github.com/docker/distribution/registry/client/auth/challenge"
"github.com/docker/distribution/registry/client/transport"
godigest "github.com/opencontainers/go-digest"
)
// RepositoryRetriever fetches a Docker distribution.Repository.
type RepositoryRetriever interface {
// Repository returns a properly authenticated distribution.Repository for the given registry, repository
// name, and insecure toleration behavior.
Repository(ctx gocontext.Context, registry *url.URL, repoName string, insecure bool) (distribution.Repository, error)
}
// ErrNotV2Registry is returned when the server does not report itself as a V2 Docker registry
type ErrNotV2Registry struct {
Registry string
}
func (e *ErrNotV2Registry) Error() string {
return fmt.Sprintf("endpoint %q does not support v2 API", e.Registry)
}
type AuthHandlersFunc func(transport http.RoundTripper, registry *url.URL, repoName string) []auth.AuthenticationHandler
// NewContext is capable of creating RepositoryRetrievers.
func NewContext(transport, insecureTransport http.RoundTripper) *Context {
return &Context{
Transport: transport,
InsecureTransport: insecureTransport,
Challenges: challenge.NewSimpleManager(),
Actions: []string{"pull"},
Retries: 2,
Credentials: NoCredentials,
pings: make(map[url.URL]error),
redirect: make(map[url.URL]*url.URL),
}
}
type transportCache struct {
rt http.RoundTripper
scopes map[string]struct{}
transport http.RoundTripper
}
type Context struct {
Transport http.RoundTripper
InsecureTransport http.RoundTripper
Challenges challenge.Manager
Scopes []auth.Scope
Actions []string
Retries int
Credentials auth.CredentialStore
lock sync.Mutex
pings map[url.URL]error
redirect map[url.URL]*url.URL
cachedTransports []transportCache
}
func (c *Context) Copy() *Context {
c.lock.Lock()
defer c.lock.Unlock()
copied := &Context{
Transport: c.Transport,
InsecureTransport: c.InsecureTransport,
Challenges: c.Challenges,
Scopes: c.Scopes,
Actions: c.Actions,
Retries: c.Retries,
Credentials: c.Credentials,
pings: make(map[url.URL]error),
redirect: make(map[url.URL]*url.URL),
}
for k, v := range c.redirect {
copied.redirect[k] = v
}
return copied
}
func (c *Context) WithScopes(scopes ...auth.Scope) *Context {
c.Scopes = scopes
return c
}
func (c *Context) WithActions(actions ...string) *Context {
c.Actions = actions
return c
}
func (c *Context) WithCredentials(credentials auth.CredentialStore) *Context {
c.Credentials = credentials
return c
}
// Reset clears any cached repository info for this context.
func (c *Context) Reset() {
c.lock.Lock()
defer c.lock.Unlock()
c.pings = nil
c.redirect = nil
}
func (c *Context) cachedPing(src url.URL) (*url.URL, error) {
c.lock.Lock()
defer c.lock.Unlock()
err, ok := c.pings[src]
if !ok {
return nil, nil
}
if err != nil {
return nil, err
}
if redirect, ok := c.redirect[src]; ok {
src = *redirect
}
return &src, nil
}
// Ping contacts a registry and returns the transport and URL of the registry or an error.
func (c *Context) Ping(ctx gocontext.Context, registry *url.URL, insecure bool) (http.RoundTripper, *url.URL, error) {
t := c.Transport
if insecure && c.InsecureTransport != nil {
t = c.InsecureTransport
}
src := *registry
if len(src.Scheme) == 0 {
src.Scheme = "https"
}
// reused cached pings
url, err := c.cachedPing(src)
if err != nil {
return nil, nil, err
}
if url != nil {
return t, url, nil
}
// follow redirects
redirect, err := c.ping(src, insecure, t)
c.lock.Lock()
defer c.lock.Unlock()
c.pings[src] = err
if err != nil {
return nil, nil, err
}
if redirect != nil {
c.redirect[src] = redirect
src = *redirect
}
return t, &src, nil
}
func (c *Context) Repository(ctx gocontext.Context, registry *url.URL, repoName string, insecure bool) (distribution.Repository, error) {
named, err := reference.WithName(repoName)
if err != nil {
return nil, err
}
rt, src, err := c.Ping(ctx, registry, insecure)
if err != nil {
return nil, err
}
rt = c.repositoryTransport(rt, src, repoName)
repo, err := registryclient.NewRepository(context.Context(ctx), named, src.String(), rt)
if err != nil {
return nil, err
}
if c.Retries > 0 {
return NewRetryRepository(repo, c.Retries, 3/2*time.Second), nil
}
return repo, nil
}
func (c *Context) ping(registry url.URL, insecure bool, transport http.RoundTripper) (*url.URL, error) {
pingClient := &http.Client{
Transport: transport,
Timeout: 15 * time.Second,
}
target := registry
target.Path = path.Join(target.Path, "v2") + "/"
req, err := http.NewRequest("GET", target.String(), nil)
if err != nil {
return nil, err
}
resp, err := pingClient.Do(req)
if err != nil {
if insecure && registry.Scheme == "https" {
glog.V(5).Infof("Falling back to an HTTP check for an insecure registry %s: %v", registry.String(), err)
registry.Scheme = "http"
_, nErr := c.ping(registry, true, transport)
if nErr != nil {
return nil, nErr
}
return ®istry, nil
}
return nil, err
}
defer resp.Body.Close()
versions := auth.APIVersions(resp, "Docker-Distribution-API-Version")
if len(versions) == 0 {
glog.V(5).Infof("Registry responded to v2 Docker endpoint, but has no header for Docker Distribution %s: %d, %#v", req.URL, resp.StatusCode, resp.Header)
switch {
case resp.StatusCode >= 200 && resp.StatusCode < 300:
// v2
case resp.StatusCode == http.StatusUnauthorized, resp.StatusCode == http.StatusForbidden:
// v2
default:
return nil, &ErrNotV2Registry{Registry: registry.String()}
}
}
c.Challenges.AddResponse(resp)
return nil, nil
}
func hasAll(a, b map[string]struct{}) bool {
for key := range b {
if _, ok := a[key]; !ok {
return false
}
}
return true
}
type stringScope string
func (s stringScope) String() string { return string(s) }
// cachedTransport reuses an underlying transport for the given round tripper based
// on the set of passed scopes. It will always return a transport that has at least the
// provided scope list.
func (c *Context) cachedTransport(rt http.RoundTripper, scopes []auth.Scope) http.RoundTripper {
scopeNames := make(map[string]struct{})
for _, scope := range scopes {
scopeNames[scope.String()] = struct{}{}
}
c.lock.Lock()
defer c.lock.Unlock()
for _, c := range c.cachedTransports {
if c.rt == rt && hasAll(c.scopes, scopeNames) {
return c.transport
}
}
// avoid taking a dependency on kube sets.String for minimal dependencies
names := make([]string, 0, len(scopeNames))
for s := range scopeNames {
names = append(names, s)
}
sort.Strings(names)
scopes = make([]auth.Scope, 0, len(scopeNames))
for _, s := range names {
scopes = append(scopes, stringScope(s))
}
t := transport.NewTransport(
rt,
// TODO: slightly smarter authorizer that retries unauthenticated requests
// TODO: make multiple attempts if the first credential fails
auth.NewAuthorizer(
c.Challenges,
auth.NewTokenHandlerWithOptions(auth.TokenHandlerOptions{
Transport: rt,
Credentials: c.Credentials,
Scopes: scopes,
}),
auth.NewBasicHandler(c.Credentials),
),
)
c.cachedTransports = append(c.cachedTransports, transportCache{
rt: rt,
scopes: scopeNames,
transport: t,
})
return t
}
func (c *Context) scopes(repoName string) []auth.Scope {
scopes := make([]auth.Scope, 0, 1+len(c.Scopes))
scopes = append(scopes, c.Scopes...)
if len(c.Actions) == 0 {
scopes = append(scopes, auth.RepositoryScope{Repository: repoName, Actions: []string{"pull"}})
} else {
scopes = append(scopes, auth.RepositoryScope{Repository: repoName, Actions: c.Actions})
}
return scopes
}
func (c *Context) repositoryTransport(t http.RoundTripper, registry *url.URL, repoName string) http.RoundTripper {
return c.cachedTransport(t, c.scopes(repoName))
}
var nowFn = time.Now
type retryRepository struct {
distribution.Repository
retries int
wait time.Duration
}
// NewRetryRepository wraps a distribution.Repository with helpers that will retry authentication failures
// over a limited time window and duration. This primarily avoids a DockerHub issue where public images
// unexpectedly return a 401 error due to the JWT token created by the hub being created at the same second,
// but another server being in the previous second.
func NewRetryRepository(repo distribution.Repository, retries int, interval time.Duration) distribution.Repository {
var wait time.Duration
if retries > 1 {
wait = interval / time.Duration(retries-1)
}
return &retryRepository{
Repository: repo,
retries: retries,
wait: wait,
}
}
// isTemporaryHTTPError returns true if the error indicates a temporary or partial HTTP failure
func isTemporaryHTTPError(err error) bool {
if e, ok := err.(net.Error); ok && e != nil {
return e.Temporary() || e.Timeout()
}
return false
}
// shouldRetry returns true if the error was temporary and count is less than retries.
func (c *retryRepository) shouldRetry(count int, err error) bool {
if err == nil {
return false
}
if !isTemporaryHTTPError(err) {
return false
}
if count >= c.retries {
return false
}
// don't hot loop
time.Sleep(c.wait)
glog.V(4).Infof("Retrying request to Docker registry after encountering error (%d attempts remaining): %v", count, err)
return true
}
// Manifests wraps the manifest service in a retryManifest for shared retries.
func (c *retryRepository) Manifests(ctx context.Context, options ...distribution.ManifestServiceOption) (distribution.ManifestService, error) {
s, err := c.Repository.Manifests(ctx, options...)
if err != nil {
return nil, err
}
return retryManifest{ManifestService: s, repo: c}, nil
}
// Blobs wraps the blob service in a retryBlobStore for shared retries.
func (c *retryRepository) Blobs(ctx context.Context) distribution.BlobStore {
return retryBlobStore{BlobStore: c.Repository.Blobs(ctx), repo: c}
}
// Tags lists the tags under the named repository.
func (c *retryRepository) Tags(ctx context.Context) distribution.TagService {
return &retryTags{TagService: c.Repository.Tags(ctx), repo: c}
}
// retryManifest wraps the manifest service and invokes retries on the repo.
type retryManifest struct {
distribution.ManifestService
repo *retryRepository
}
// Exists returns true if the manifest exists.
func (c retryManifest) Exists(ctx context.Context, dgst godigest.Digest) (bool, error) {
for i := 0; ; i++ {
exists, err := c.ManifestService.Exists(ctx, dgst)
if c.repo.shouldRetry(i, err) {
continue
}
return exists, err
}
}
// Get retrieves the manifest identified by the digest, if it exists.
func (c retryManifest) Get(ctx context.Context, dgst godigest.Digest, options ...distribution.ManifestServiceOption) (distribution.Manifest, error) {
for i := 0; ; i++ {
m, err := c.ManifestService.Get(ctx, dgst, options...)
if c.repo.shouldRetry(i, err) {
continue
}
return m, err
}
}
// retryBlobStore wraps the blob store and invokes retries on the repo.
type retryBlobStore struct {
distribution.BlobStore
repo *retryRepository
}
func (c retryBlobStore) Stat(ctx context.Context, dgst godigest.Digest) (distribution.Descriptor, error) {
for i := 0; ; i++ {
d, err := c.BlobStore.Stat(ctx, dgst)
if c.repo.shouldRetry(i, err) {
continue
}
return d, err
}
}
func (c retryBlobStore) ServeBlob(ctx context.Context, w http.ResponseWriter, req *http.Request, dgst godigest.Digest) error {
for i := 0; ; i++ {
err := c.BlobStore.ServeBlob(ctx, w, req, dgst)
if c.repo.shouldRetry(i, err) {
continue
}
return err
}
}
func (c retryBlobStore) Open(ctx context.Context, dgst godigest.Digest) (distribution.ReadSeekCloser, error) {
for i := 0; ; i++ {
rsc, err := c.BlobStore.Open(ctx, dgst)
if c.repo.shouldRetry(i, err) {
continue
}
return rsc, err
}
}
type retryTags struct {
distribution.TagService
repo *retryRepository
}
func (c *retryTags) Get(ctx context.Context, tag string) (distribution.Descriptor, error) {
for i := 0; ; i++ {
t, err := c.TagService.Get(ctx, tag)
if c.repo.shouldRetry(i, err) {
continue
}
return t, err
}
}
func (c *retryTags) All(ctx context.Context) ([]string, error) {
for i := 0; ; i++ {
t, err := c.TagService.All(ctx)
if c.repo.shouldRetry(i, err) {
continue
}
return t, err
}
}
func (c *retryTags) Lookup(ctx context.Context, digest distribution.Descriptor) ([]string, error) {
for i := 0; ; i++ {
t, err := c.TagService.Lookup(ctx, digest)
if c.repo.shouldRetry(i, err) {
continue
}
return t, err
}
}