Prevent push and pull to v1 registries by filtering the available endpoints.

Add a daemon flag to control this behaviour.  Add a warning message when pulling
an image from a v1 registry.  The default order of pull is slightly altered
with this changset.

Previously it was:
https v2, https v1, http v2, http v1

now it is:
https v2, http v2, https v1, http v1

Prevent login to v1 registries by explicitly setting the version before ping to
prevent fallback to v1.

Add unit tests for v2 only mode.  Create a mock server that can register
handlers for various endpoints.  Assert no v1 endpoints are hit with legacy
registries disabled for the following commands:  pull, push, build, run and
login.  Assert the opposite when legacy registries are not disabled.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>

docs/service.go

@@ -2,15 +2,11 @@ package registry
 
 import (
 	"crypto/tls"
-	"fmt"
 	"net/http"
 	"net/url"
-	"runtime"
-	"strings"
 
 	"github.com/docker/distribution/registry/client/auth"
 	"github.com/docker/docker/cliconfig"
-	"github.com/docker/docker/pkg/tlsconfig"
 )
 
 // Service is a registry service. It tracks configuration data such as a list
@@ -40,7 +36,14 @@ func (s *Service) Auth(authConfig *cliconfig.AuthConfig) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	endpoint, err := NewEndpoint(index, nil)
+
+	endpointVersion := APIVersion(APIVersionUnknown)
+	if V2Only {
+		// Override the endpoint to only attempt a v2 ping
+		endpointVersion = APIVersion2
+	}
+
+	endpoint, err := NewEndpoint(index, nil, endpointVersion)
 	if err != nil {
 		return "", err
 	}
@@ -57,10 +60,11 @@ func (s *Service) Search(term string, authConfig *cliconfig.AuthConfig, headers
 	}
 
 	// *TODO: Search multiple indexes.
-	endpoint, err := repoInfo.GetEndpoint(http.Header(headers))
+	endpoint, err := NewEndpoint(repoInfo.Index, http.Header(headers), APIVersionUnknown)
 	if err != nil {
 		return nil, err
 	}
+
 	r, err := NewSession(endpoint.client, authConfig, endpoint)
 	if err != nil {
 		return nil, err
@@ -132,97 +136,20 @@ func (s *Service) LookupPushEndpoints(repoName string) (endpoints []APIEndpoint,
 }
 
 func (s *Service) lookupEndpoints(repoName string) (endpoints []APIEndpoint, err error) {
-	var cfg = tlsconfig.ServerDefault
-	tlsConfig := &cfg
-	if strings.HasPrefix(repoName, DefaultNamespace+"/") {
-		// v2 mirrors
-		for _, mirror := range s.Config.Mirrors {
-			mirrorTLSConfig, err := s.tlsConfigForMirror(mirror)
-			if err != nil {
-				return nil, err
-			}
-			endpoints = append(endpoints, APIEndpoint{
-				URL: mirror,
-				// guess mirrors are v2
-				Version:      APIVersion2,
-				Mirror:       true,
-				TrimHostname: true,
-				TLSConfig:    mirrorTLSConfig,
-			})
-		}
-		// v2 registry
-		endpoints = append(endpoints, APIEndpoint{
-			URL:          DefaultV2Registry,
-			Version:      APIVersion2,
-			Official:     true,
-			TrimHostname: true,
-			TLSConfig:    tlsConfig,
-		})
-		if runtime.GOOS == "linux" { // do not inherit legacy API for OSes supported in the future
-			// v1 registry
-			endpoints = append(endpoints, APIEndpoint{
-				URL:          DefaultV1Registry,
-				Version:      APIVersion1,
-				Official:     true,
-				TrimHostname: true,
-				TLSConfig:    tlsConfig,
-			})
-		}
-		return endpoints, nil
-	}
-
-	slashIndex := strings.IndexRune(repoName, '/')
-	if slashIndex <= 0 {
-		return nil, fmt.Errorf("invalid repo name: missing '/':  %s", repoName)
-	}
-	hostname := repoName[:slashIndex]
-
-	tlsConfig, err = s.TLSConfig(hostname)
+	endpoints, err = s.lookupV2Endpoints(repoName)
 	if err != nil {
 		return nil, err
 	}
-	isSecure := !tlsConfig.InsecureSkipVerify
 
-	v2Versions := []auth.APIVersion{
-		{
-			Type:    "registry",
-			Version: "2.0",
-		},
-	}
-	endpoints = []APIEndpoint{
-		{
-			URL:           "https://" + hostname,
-			Version:       APIVersion2,
-			TrimHostname:  true,
-			TLSConfig:     tlsConfig,
-			VersionHeader: DefaultRegistryVersionHeader,
-			Versions:      v2Versions,
-		},
-		{
-			URL:          "https://" + hostname,
-			Version:      APIVersion1,
-			TrimHostname: true,
-			TLSConfig:    tlsConfig,
-		},
+	if V2Only {
+		return endpoints, nil
 	}
 
-	if !isSecure {
-		endpoints = append(endpoints, APIEndpoint{
-			URL:          "http://" + hostname,
-			Version:      APIVersion2,
-			TrimHostname: true,
-			// used to check if supposed to be secure via InsecureSkipVerify
-			TLSConfig:     tlsConfig,
-			VersionHeader: DefaultRegistryVersionHeader,
-			Versions:      v2Versions,
-		}, APIEndpoint{
-			URL:          "http://" + hostname,
-			Version:      APIVersion1,
-			TrimHostname: true,
-			// used to check if supposed to be secure via InsecureSkipVerify
-			TLSConfig: tlsConfig,
-		})
+	legacyEndpoints, err := s.lookupV1Endpoints(repoName)
+	if err != nil {
+		return nil, err
 	}
+	endpoints = append(endpoints, legacyEndpoints...)
 
 	return endpoints, nil
 }