Update vendor

vendor/github.com/google/go-containerregistry/pkg/authn/keychain.go

@@ -0,0 +1,89 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package authn
+
+import (
+	"os"
+
+	"github.com/docker/cli/cli/config"
+	"github.com/docker/cli/cli/config/types"
+	"github.com/google/go-containerregistry/pkg/name"
+)
+
+// Resource represents a registry or repository that can be authenticated against.
+type Resource interface {
+	// String returns the full string representation of the target, e.g.
+	// gcr.io/my-project or just gcr.io.
+	String() string
+
+	// RegistryStr returns just the registry portion of the target, e.g. for
+	// gcr.io/my-project, this should just return gcr.io. This is needed to
+	// pull out an appropriate hostname.
+	RegistryStr() string
+}
+
+// Keychain is an interface for resolving an image reference to a credential.
+type Keychain interface {
+	// Resolve looks up the most appropriate credential for the specified target.
+	Resolve(Resource) (Authenticator, error)
+}
+
+// defaultKeychain implements Keychain with the semantics of the standard Docker
+// credential keychain.
+type defaultKeychain struct{}
+
+var (
+	// DefaultKeychain implements Keychain by interpreting the docker config file.
+	DefaultKeychain Keychain = &defaultKeychain{}
+)
+
+const (
+	// DefaultAuthKey is the key used for dockerhub in config files, which
+	// is hardcoded for historical reasons.
+	DefaultAuthKey = "https://" + name.DefaultRegistry + "/v1/"
+)
+
+// Resolve implements Keychain.
+func (dk *defaultKeychain) Resolve(target Resource) (Authenticator, error) {
+	cf, err := config.Load(os.Getenv("DOCKER_CONFIG"))
+	if err != nil {
+		return nil, err
+	}
+
+	// See:
+	// https://github.com/google/ko/issues/90
+	// https://github.com/moby/moby/blob/fc01c2b481097a6057bec3cd1ab2d7b4488c50c4/registry/config.go#L397-L404
+	key := target.RegistryStr()
+	if key == name.DefaultRegistry {
+		key = DefaultAuthKey
+	}
+
+	cfg, err := cf.GetAuthConfig(key)
+	if err != nil {
+		return nil, err
+	}
+
+	empty := types.AuthConfig{}
+	if cfg == empty {
+		return Anonymous, nil
+	}
+	return FromConfig(AuthConfig{
+		Username:      cfg.Username,
+		Password:      cfg.Password,
+		Auth:          cfg.Auth,
+		IdentityToken: cfg.IdentityToken,
+		RegistryToken: cfg.RegistryToken,
+	}), nil
+}