cli: introduce NotaryClient getter

Signed-off-by: Riyaz Faizullabhoy <riyaz.faizullabhoy@docker.com>

cli/command/cli.go

@@ -12,13 +12,18 @@ import (
 	cliconfig "github.com/docker/cli/cli/config"
 	"github.com/docker/cli/cli/config/configfile"
 	cliflags "github.com/docker/cli/cli/flags"
+	"github.com/docker/cli/cli/trust"
 	dopts "github.com/docker/cli/opts"
+	"github.com/docker/distribution/reference"
 	"github.com/docker/docker/api"
 	"github.com/docker/docker/client"
+	"github.com/docker/docker/registry"
 	"github.com/docker/go-connections/sockets"
 	"github.com/docker/go-connections/tlsconfig"
 	"github.com/docker/notary"
+	notaryclient "github.com/docker/notary/client"
 	"github.com/docker/notary/passphrase"
+	digest "github.com/opencontainers/go-digest"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"golang.org/x/net/context"
@@ -40,6 +45,7 @@ type Cli interface {
 	SetIn(in *InStream)
 	ConfigFile() *configfile.ConfigFile
 	ServerInfo() ServerInfo
+	NotaryClient(imgRefAndAuth trust.ImageRefAndAuth, actions []string) (notaryclient.Repository, error)
 }
 
 // DockerCli is an instance the docker command line client.
@@ -161,6 +167,51 @@ func getClientWithPassword(passRetriever notary.PassRetriever, newClient func(pa
 	}
 }
 
+// NotaryClient provides a Notary Repository to interact with signed metadata for an image
+func (cli *DockerCli) NotaryClient(imgRefAndAuth trust.ImageRefAndAuth, actions []string) (notaryclient.Repository, error) {
+	return trust.GetNotaryRepository(cli.In(), cli.Out(), UserAgent(), imgRefAndAuth.RepoInfo(), imgRefAndAuth.AuthConfig(), actions...)
+}
+
+// GetImageReferencesAndAuth retrieves the necessary reference and auth information for an image name
+// as a ImageRefAndAuth struct
+func GetImageReferencesAndAuth(ctx context.Context, cli Cli, imgName string) (*trust.ImageRefAndAuth, error) {
+	ref, err := reference.ParseNormalizedNamed(imgName)
+	if err != nil {
+		return nil, err
+	}
+
+	// Resolve the Repository name from fqn to RepositoryInfo
+	repoInfo, err := registry.ParseRepositoryInfo(ref)
+	if err != nil {
+		return nil, err
+	}
+
+	authConfig := ResolveAuthConfig(ctx, cli, repoInfo.Index)
+	return trust.NewImageRefAndAuth(&authConfig, ref, repoInfo, getTag(ref), getDigest(ref)), nil
+}
+
+func getTag(ref reference.Named) string {
+	switch x := ref.(type) {
+	case reference.Canonical, reference.Digested:
+		return ""
+	case reference.NamedTagged:
+		return x.Tag()
+	default:
+		return ""
+	}
+}
+
+func getDigest(ref reference.Named) digest.Digest {
+	switch x := ref.(type) {
+	case reference.Canonical:
+		return x.Digest()
+	case reference.Digested:
+		return x.Digest()
+	default:
+		return digest.Digest("")
+	}
+}
+
 // ServerInfo stores details about the supported features and platform of the
 // server
 type ServerInfo struct {