Add credentials/oauth

credentials/oauth/oauth.go

@@ -0,0 +1,115 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+// Package oauth implements gRPC credentials using OAuth.
+package oauth
+
+import (
+	"fmt"
+	"io/ioutil"
+
+	"golang.org/x/net/context"
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google"
+	"golang.org/x/oauth2/jwt"
+	"google.golang.org/grpc/credentials"
+)
+
+// TokenSource supplies credentials from an oauth2.TokenSource.
+type TokenSource struct {
+	oauth2.TokenSource
+}
+
+// GetRequestMetadata gets the request metadata as a map from a TokenSource.
+func (ts TokenSource) GetRequestMetadata(ctx context.Context) (map[string]string, error) {
+	token, err := ts.Token()
+	if err != nil {
+		return nil, err
+	}
+	return map[string]string{
+		"authorization": token.TokenType + " " + token.AccessToken,
+	}, nil
+}
+
+// NewComputeEngine constructs the credentials that fetches access tokens from
+// Google Compute Engine (GCE)'s metadata server. It is only valid to use this
+// if your program is running on a GCE instance.
+// TODO(dsymonds): Deprecate and remove this.
+func NewComputeEngine() credentials.Credentials {
+	return TokenSource{google.ComputeTokenSource("")}
+}
+
+// serviceAccount represents credentials via JWT signing key.
+type serviceAccount struct {
+	config *jwt.Config
+}
+
+func (s serviceAccount) GetRequestMetadata(ctx context.Context) (map[string]string, error) {
+	token, err := s.config.TokenSource(ctx).Token()
+	if err != nil {
+		return nil, err
+	}
+	return map[string]string{
+		"authorization": token.TokenType + " " + token.AccessToken,
+	}, nil
+}
+
+// NewServiceAccountFromKey constructs the credentials using the JSON key slice
+// from a Google Developers service account.
+func NewServiceAccountFromKey(jsonKey []byte, scope ...string) (credentials.Credentials, error) {
+	config, err := google.JWTConfigFromJSON(jsonKey, scope...)
+	if err != nil {
+		return nil, err
+	}
+	return serviceAccount{config: config}, nil
+}
+
+// NewServiceAccountFromFile constructs the credentials using the JSON key file
+// of a Google Developers service account.
+func NewServiceAccountFromFile(keyFile string, scope ...string) (credentials.Credentials, error) {
+	jsonKey, err := ioutil.ReadFile(keyFile)
+	if err != nil {
+		return nil, fmt.Errorf("credentials: failed to read the service account key file: %v", err)
+	}
+	return NewServiceAccountFromKey(jsonKey, scope...)
+}
+
+// NewApplicationDefault returns "Application Default Credentials". For more
+// detail, see https://developers.google.com/accounts/docs/application-default-credentials.
+func NewApplicationDefault(ctx context.Context, scope ...string) (credentials.Credentials, error) {
+	t, err := google.DefaultTokenSource(ctx, scope...)
+	if err != nil {
+		return nil, err
+	}
+	return TokenSource{t}, nil
+}