registry: remove ping v1

The ping v1 happens when the ping v2 fails, however, it causes the ping
v2 error to be skipped and not output to the user. As result, when a
registry has v1 and v2 enabled, and there are, for example, intermittent
connectivity issues making the ping v2 fail, the user is presented with
a misleading error saying "can't talk to V1 registry."

Since the only use of v1 is for the search API as a workaround for
docker.io, and new container registries setups are very unlikely to be
v1-only, there is little utility in keeping this v1 detection in the
attempt to help the user realize their setup is v1-only, hence not
compatible. On the contratry, it just presents the user with a
misleading error in certain circumstances.

Signed-off-by: Carlos Rodriguez-Fernandez <[email protected]>

docker/docker_client.go

@@ -42,7 +42,6 @@ const (
 	dockerRegistry   = "registry-1.docker.io"
 
 	resolvedPingV2URL       = "%s://%s/v2/"
-	resolvedPingV1URL       = "%s://%s/v1/_ping"
 	tagsPath                = "/v2/%s/tags/list"
 	manifestPath            = "/v2/%s/manifests/%s"
 	blobsPath               = "/v2/%s/blobs/%s"
@@ -936,34 +935,6 @@ func (c *dockerClient) detectPropertiesHelper(ctx context.Context) error {
 	}
 	if err != nil {
 		err = fmt.Errorf("pinging container registry %s: %w", c.registry, err)
-		if c.sys != nil && c.sys.DockerDisableV1Ping {
-			return err
-		}
-		// best effort to understand if we're talking to a V1 registry
-		pingV1 := func(scheme string) bool {
-			pingURL, err := url.Parse(fmt.Sprintf(resolvedPingV1URL, scheme, c.registry))
-			if err != nil {
-				return false
-			}
-			resp, err := c.makeRequestToResolvedURL(ctx, http.MethodGet, pingURL, nil, nil, -1, noAuth, nil)
-			if err != nil {
-				logrus.Debugf("Ping %s err %s (%#v)", pingURL.Redacted(), err.Error(), err)
-				return false
-			}
-			defer resp.Body.Close()
-			logrus.Debugf("Ping %s status %d", pingURL.Redacted(), resp.StatusCode)
-			if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusUnauthorized {
-				return false
-			}
-			return true
-		}
-		isV1 := pingV1("https")
-		if !isV1 && c.tlsClientConfig.InsecureSkipVerify {
-			isV1 = pingV1("http")
-		}
-		if isV1 {
-			err = ErrV1NotSupported
-		}
 	}
 	return err
 }

docker/errors.go

@@ -12,6 +12,7 @@ import (
 var (
 	// ErrV1NotSupported is returned when we're trying to talk to a
 	// docker V1 registry.
+	// Deprecated: The V1 container registry detection is no longer performed, so this error is never returned.
 	ErrV1NotSupported = errors.New("can't talk to a V1 container registry")
 	// ErrTooManyRequests is returned when the status code returned is 429
 	ErrTooManyRequests = errors.New("too many requests to registry")

types/types.go

@@ -643,6 +643,7 @@ type SystemContext struct {
 	// if true, a V1 ping attempt isn't done to give users a better error. Default is false.
 	// Note that this field is used mainly to integrate containers/image into projectatomic/docker
 	// in order to not break any existing docker's integration tests.
+	// Deprecated: The V1 container registry detection is no longer performed, so setting this flag has no effect.
 	DockerDisableV1Ping bool
 	// If true, dockerImageDestination.SupportedManifestMIMETypes will omit the Schema1 media types from the supported list
 	DockerDisableDestSchema1MIMETypes bool