n2parko/gcpsamples

Google Cloud Platform Samples

samples provided as-is without warranty

Sample code demonstrating various Auth mechanism for Google Cloud Platform APIs.

Please refer to official documentation for usage and additional samples/usage.

Application Default Credentials

The samples use Application Default Credentials which uses credentials in the following order as described in the link. Set the environment variable to override.

You can always specify the target source to acquire credentials by using intent specific targets such as: ComputeCredentials, UserCredentials or ServiceAccountCredential.

There are two types of client libraries you can use to connect to Google APIs:

Google Cloud Client Libraries
Gooogle API Client Libraries

The basic differences is the Cloud Client libraries are idomatic, has gcloud-based emulators and much eaiser to use.

It is recommended to use Cloud Client Libraries whereever possible. Although this article primarily describes the API Client libraries, the python code section describes uses of Cloud Client libraries with Google Cloud Storage.

For more information, see

This article also describes how to use IAM's serviceAccountActor role to issue access_tokens, id_tokens and JWT. For more information on that, see auth/tokens/.

The following examples use the Oauth2 service to demonstrate the initialized client using Google API Client Libraries. The first section is about the different client libraries you can use.

Cloud Client Libraries and API Client Libraries
- Cloud Client Libraries
- API Client Libraries
Cloud Client Libraries
- Python
- Java
- Go
- Node
- c#
- gRPC Environment Variables
API Client Library
- Python
- Java
- Go
- Node
- C#
serviceAccountActor role for impersonation
- access_token
- id_token
- JWT

For more inforamtion, see:

GoogleLibraries

As described in the introduciton, this section details the two types of libraries you can use to access Google Services:

Google Cloud Client Libraries

These libraries are idomatic, easy to use and even support the gcloud-based emulator framework. This is the recommended library set to use to access Google Cloud APIs.

For more information, see:

The following example describes various ways to initialize a service account to list the Google Cloud Storage buckets the account has access to. It also shows listing the buckets using the default account currently initialized by gcloud.

To use the mechanisms here, you need to initialize gcloud's application defaults:

gcloud beta auth application-default login

Cloud Python

The following uses the google-storage client described here: Storage Client

virtualenv env 
source env/bin/activate
pip install google-cloud

Name: google-cloud
Version: 0.22.0

The following lists some of the various mechanisms to acquire credentials:

List buckets using the default account on the current gcloud cli (preferred)

from google.cloud import storage

client = storage.Client()
buckets = client.list_buckets()
for bkt in buckets:
  print bkt

List buckts using gcloud cli explicit credential and project

from google.cloud import storage
import google.auth

credentials, project = google.auth.default()    
client = storage.Client(credentials=credentials)
buckets = client.list_buckets()
for bkt in buckets:
  print bkt

List buckets using an environment variable and then google.auth.default() credentials.

from google.cloud import storage
import google.auth

os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "YOUR_JSON_CERT.json"
credentials, project = google.auth.default()
if credentials.requires_scopes:
  credentials = credentials.with_scopes(['https://www.googleapis.com/auth/devstorage.read_write'])
client = storage.Client(credentials=credentials)
buckets = client.list_buckets()
for bkt in buckets:
  print bkt

List buckets using a service_account oauth2 object directly

from google.cloud import storage
import google.auth
from google.oauth2 import service_account

credentials = service_account.Credentials.from_service_account_file('YOUR_JSON_CERT.json')
if credentials.requires_scopes:
  credentials = credentials.with_scopes(['https://www.googleapis.com/auth/devstorage.read_write'])

client = storage.Client(credentials=credentials)
buckets = client.list_buckets()
for bkt in buckets:
  print bkt

List buckets using the storage client directly loading the certificate:

from google.cloud import storage

client = storage.Client.from_service_account_json("YOUR_JSON_CERT.json")
buckets = client.list_buckets()
for bkt in buckets:
  print bkt

Iterators

see google cloud python iterators

import os
#os.environ["GOOGLE_CLOUD_DISABLE_GRPC"] = "true"

from google.cloud import logging
from google.cloud.logging import DESCENDING

FILTER = 'resource.type="gae_app" AND logName="projects/mineral-minutia-820/logs/appengine.googleapis.com%2Frequest_log" AND protoPayload.resource="/"'
client = logging.Client()
iterator = client.list_entries(filter_=FILTER, order_by=DESCENDING)
for page in iterator.pages:
  print('    Page number: %d' % (iterator.page_number,))
  print('  Items in page: %d' % (page.num_items,))
  print('Items remaining: %d' % (page.remaining,))
  print('Next page token: %s' % (iterator.next_page_token,))  
  print('----------------------------')    
  for entry in page:
      print(entry.timestamp)

Cloud Java

The following describes using java default credentials. You can explictly setCredentials() while initializing a service but that is not recommended as the code is not portable

The various credential types can be found here:

import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.Blob.BlobSourceOption;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.BlobInfo;

import com.google.cloud.storage.Storage.SignUrlOption;
import java.util.concurrent.TimeUnit;
import java.net.URL;
import java.util.Iterator;
import java.io.FileInputStream;


//import com.google.auth.oauth2.ServiceAccountCredentials;

// Using Google Cloud APIs with service account file
// You can also just export an export GOOGLE_APPLICATION_CREDENTIALS and use StorageOptions.defaultInstance().service()
// see https://github.com/google/google-auth-library-java#google-auth-library-oauth2-http
/*
Storage storage_service = StorageOptions.newBuilder()
			.setCredentials(ServiceAccountCredentials.fromStream(new FileInputStream("/path/to/your/certificate.json")))
			.build()
			.getService();			
*/

Storage  storage_service = StorageOptions.defaultInstance().service();
        
Iterator<Bucket> bucketIterator = storage_service.list().iterateAll();
while (bucketIterator.hasNext()) {
  System.out.println(bucketIterator.next());
}


URL signedUrl = storage_service.signUrl(BlobInfo.newBuilder("your_project", "a.txt").build(), 60,  TimeUnit.SECONDS);
System.out.println(signedUrl);

Proxy Server Settings

https://github.com/grpc/grpc-java/releases/tag/v1.0.3

export  GRPC_PROXY_EXP=proxy_server:3128

Credential Providers

import com.google.api.gax.grpc.InstantiatingChannelProvider;
import com.google.api.gax.core.GoogleCredentialsProvider;
import com.google.api.gax.core.FixedCredentialsProvider;
import com.google.auth.oauth2.ServiceAccountCredentials;
import com.google.auth.Credentials;

	String cert_file = "GCPNETAppID-e65deccae47b.json";
    //export GOOGLE_APPLICATION_CREDENTIALS="/path/to/keyfile.json" 

    String cred_env = System.getenv("GOOGLE_APPLICATION_CREDENTIALS");
    System.out.println(cred_env);
    List<String> ll = Arrays.asList("https://www.googleapis.com/auth/cloud-platform");

    //GoogleCredentialsProvider myprovider = GoogleCredentialsProvider.newBuilder().setScopesToApply(ll).build();
    ServiceAccountCredentials creds = ServiceAccountCredentials.fromStream(new FileInputStream(cert_file));
    
    FixedCredentialsProvider myprovider = FixedCredentialsProvider.create(creds);
    System.out.println(myprovider.getCredentials() );

     InstantiatingChannelProvider channelProvider = TopicAdminSettings.defaultChannelProviderBuilder()
        .setCredentialsProvider(myprovider)
        .build();

Async Futures

import com.google.api.client.http.HttpTransport;
import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.cloud.pubsub.spi.v1.Publisher;
import com.google.cloud.pubsub.spi.v1.TopicAdminClient;
import com.google.cloud.pubsub.spi.v1.TopicAdminSettings;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.Topic;
import com.google.pubsub.v1.TopicName;

import com.google.api.gax.grpc.InstantiatingChannelProvider;
import com.google.api.gax.core.GoogleCredentialsProvider;
import com.google.iam.v1.GetIamPolicyRequest;
import com.google.iam.v1.Policy;
import com.google.iam.v1.SetIamPolicyRequest;
import com.google.iam.v1.Binding;
import com.google.cloud.Role;


    List<String> ll = Arrays.asList("https://www.googleapis.com/auth/cloud-platform");
    GoogleCredentialsProvider myprovider = GoogleCredentialsProvider.newBuilder().setScopesToApply(ll).build();
    System.out.println(myprovider.getCredentials());

     InstantiatingChannelProvider channelProvider = TopicAdminSettings.defaultChannelProviderBuilder()
        .setCredentialsProvider(myprovider)
        .build();    
        
     TopicAdminSettings topicAdminSettings =  TopicAdminSettings.defaultBuilder().setChannelProvider(channelProvider).build();
     TopicAdminClient topicAdminClient =  TopicAdminClient.create(topicAdminSettings);
      String formattedResource = TopicName.create("mineral-minutia-820", "saltopic2").toString();
      
      GetIamPolicyRequest request = GetIamPolicyRequest.newBuilder()
        .setResource(formattedResource)
        .build();
      ApiFuture<Policy> future = topicAdminClient.getIamPolicyCallable().futureCall(request);
      Policy response = future.get();
      System.out.println(response);

Cloud Go

Package cloud.google.com/go/storage

The following shows google.DefaultTokenSource as well as gcloud's Application Default Credentials

import (
        "golang.org/x/net/context"
        "cloud.google.com/go/storage"
        "google.golang.org/api/iterator"
        "google.golang.org/api/option"
        "log"  
)

	ctx := context.Background()
	/*
		tokenSource, err := google.DefaultTokenSource(oauth2.NoContext, storage.ScopeReadOnly)
		if err != nil {
			log.Fatalf("Unable to acquire token source: %v", err)
		}
		storeageClient, err := storage.NewClient(ctx, option.WithTokenSource(tokenSource))
	*/

	storeageClient, err := storage.NewClient(ctx)
	if err != nil {
		log.Fatalf("Unable to acquire storage Client: %v", err)
	}

	it := storeageClient.Buckets(ctx, "your_project")
	for {
		bucketAttrs, err := it.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			log.Fatalf("Unable to acquire storage Client: %v", err)
		}
		log.Printf(bucketAttrs.Name)
	}

Exponential Backoff

Cloud libraries implement backoff automatically per service.

Cloud Node

The google-cloud node package initalizes the Cloud API library set:

var log4js = require("log4js");
var logger = log4js.getLogger();


// var gcloud = require('google-cloud')({
//  keyFilename: '/path/to/keyfile.json'
// });

var gcloud = require('google-cloud');

var gcs = gcloud.storage();

gcs.getBuckets(function(err, buckets) {
  if (!err) {
  	buckets.forEach(function(value){
  			logger.info(value.id);
	});    
  }
});

Cloud C#

Use Google.Cloud.Storage.V1 package for Google Cloud API access

using Google.Storage.V1;

namespace CloudStorageAppGcloud
{
    class Program
    {
        static void Main(string[] args)
        {
            var client = StorageClient.Create();
            
            foreach (var obj in client.ListObjects("your_project", ""))
            {
                Console.WriteLine(obj.Name);
            }
            Console.ReadLine();
        }
    }
}

gRPC Environment Variables

https://github.com/grpc/grpc/blob/master/doc/environment_variables.md

Google API Client Library for Python

The following describes the older, non-idomatic libraries. As you can see, its much easier using the idomatic library set.

GCS JSON API

virtualenv env 
source env/bin/activate
pip install --upgrade requests google-api-python-client httplib2 oauth2client

import os
import httplib2
from apiclient.discovery import build
from oauth2client.service_account import ServiceAccountCredentials
from oauth2client.client import GoogleCredentials

scope='https://www.googleapis.com/auth/devstorage.read_only'

#os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "YOUR_JSON_CERT.json"
credentials = GoogleCredentials.get_application_default()
if credentials.create_scoped_required():
  credentials = credentials.create_scoped(scope)
http = httplib2.Http()
credentials.authorize(http)

service = build(serviceName='storage', version= 'v1',http=http)
resp = service.buckets().list(project='YOUR_PROJECT').execute()
for i in resp['items']:
  print i['name']

Google API Python

Google API Client Library for Python

apt-get install curl python2.7 python-pip
pip install requests google-api-python-client httplib2 oauth2client

Appengine

Under auth/gae/pyapp/ Deploys an application to appengine that uses Application Default Credentials.

AppAssertionCredentials is also shown but commented.

Remember to edit app.yaml file with your appID.

If running on the dev_appserver, you will need to set the local service account id and certificate first:

mkdir lib
pip install --target=lib  requests google-api-python-client httplib2 oauth2client

cat your_svc_account.p12 | openssl pkcs12 -nodes -nocerts -passin pass:notasecret | openssl rsa > key.pem

gcloud preview app run app.yaml --appidentity-email-address=YOUR_SERVICE_ACCOUNT_ID@developer.gserviceaccount.com --appidentity-private-key-path=key.pem

For info on --appidentity-email-address and --appidentity-private-key-path, see documentation on gcloud dev_appserver.

ComputeEngine

Under auth/compute/pyapp Runs a simple application on compute engine using Application Default Credentials.

AppAssertionCredentials is also shown but commented

Service Account File

Under auth/service/pyapp Runs a simple application that uses the service account credential from both a PKCS12 file and a JSON keyfile. Application Default Credentials uses the JSON keyfile only if the GOOGLE_APPLICATION_CREDENTIALS variable isset

For more details, goto Service Accounts

Userflow

Under auth/userflow/pyapp Runs a simple application that performs user-interactive webflow and propmpts the user for consent. Download an installed app client_secrets.json and reference it for the 'flow_from_clientsecrets()' method.

For more deails, goto flow_from_clientsecrets

Misc

Setting API Key

Example showing how to set the API_KEY.

service = build(serviceName='oauth2', version= 'v2',http=http, developerKey='YOUR_API_KEY')

Logging

Enable verbose wire tracing.

import logging
import httplib2
import sys

logFormatter = logging.Formatter('%(asctime)s - %(name)s - %(message)s')
root = logging.getLogger()
root.setLevel(logging.INFO)           
ch = logging.StreamHandler(sys.stdout)
ch.setLevel(logging.INFO)    
ch.setFormatter(logFormatter)
root.addHandler(ch)
logging.getLogger('oauth2client.client').setLevel(logging.DEBUG)
logging.getLogger('apiclient.discovery').setLevel(logging.DEBUG) 

httplib2.debuglevel=3

Appengine Cloud Endpoints

Sample discovery for Appengine Cloud Enpoints

service = build(serviceName='myendpoint', discoveryServiceUrl='https://yourappid.appspot.com/_ah/api/discovery/v1/apis/yourendpoint/v1/rest',version= 'v1',http=http)
resource = service.yourAPI()
resp = resource.get(parameter='value').execute()

Credential store

See credential store documentation.

ID Token from Service Account JSON Signed by Google

If you need an id_token issued by Google using your JSON certificate:

from oauth2client.service_account import ServiceAccountCredentials
credentials = ServiceAccountCredentials.from_json_keyfile_name('YOUR_SERVICE_AcCOUNT.json')
now = int(time.time())
payload = {
        'iat': now,
        'exp': now + credentials.MAX_TOKEN_LIFETIME_SECS,
        'aud': 'https://www.googleapis.com/oauth2/v4/token',
        'iss': 'svc1-001@YOUR_PROJECT.iam.gserviceaccount.com',
        'scope': 'svc1-001@YOUR_PROJECT.iam.gserviceaccount.com'
}
signed_jwt = oauth2client.crypt.make_signed_jwt(credentials._signer, payload, key_id=credentials._private_key_id)
params = urllib.urlencode({
      'grant_type': 'urn:ietf:params:oauth:grant-type:jwt-bearer',
      'assertion': signed_jwt })
headers = {"Content-Type": "application/x-www-form-urlencoded"}
conn = httplib.HTTPSConnection("www.googleapis.com")
conn.request("POST", "/oauth2/v4/token", params, headers)
res = json.loads(conn.getresponse().read())
print res

Returns JSON with a JWT signed by Google:

{"id_token": "YOUR_ID_TOKEN_SIGNED_BY_GOOGLE"}

Decoded JWT id_token:

{
  "iss": "https://accounts.google.com",
  "aud": "svc1-001@YOUR_PROJECT.iam.gserviceaccount.com",
  "sub": "111402810199779215722",
  "email_verified": true,
  "azp": "svc1-001@YOUR_PROJECT.iam.gserviceaccount.com",
  "email": "svc1-001@YOUR_PROJECT.iam.gserviceaccount.com",
  "iat": 1468897846,
  "exp": 1468901446
}

In the same flow, if you used 'scope': 'https://www.googleapis.com/auth/userinfo.email', the return fields would include an access_token scoped to userinfo.email for the service account.
You do not need to explicitly recall the access_token as that is normally used internally when a Credential is initialized for a given Google API.

Google API Java

Java API Client Library. Most of the samples below uses gradle to build and deploy.

Appengine

Under auth/gae/javaapp. Runs a simple application using both Application DefaultCredentials and AppIdentityService. To deploy, edit the build.gradle file and enter the username of an administrator on the GAE application.

gradle task
gradle appengineRun
gradle appengineDeploy

mvn appengine:run
mvn appengine:deploy

ComputeEngine

Under auth/compute/javaapp. Runs a simple application using both Application DefaultCredentials and ComputeCredential.

gradle task
gradle run

mvn exec:java

Service Account File

Under auth/service/javaapp. Runs a simple application using both Application DefaultCredentials and by directly reading in the JSON certificate file. If the GOOGLE_APPLICATION_CREDENTIALS variable is set to point to the JSON file, the applicationDefault profile will also read the JSON file (otherwise, it will attempt to pick up the gcloud credentials)

export GOOGLE_APPLICATION_CREDENTIALS=/path/to/you/json/file.json
gradle task
gradle run

mvn exec:java

UserFlow

Under auth/userflow/javaapp. Runs a simple webflow application to acquire user consent for GoogleAPIs. This particular userflow launches a browser and listener.

gradle task
gradle run

mvn exec:java

Misc

Logging

import java.util.logging.ConsoleHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;

ConsoleHandler consoleHandler = new ConsoleHandler();
consoleHandler.setLevel(Level.ALL);
consoleHandler.setFormatter(new SimpleFormatter());
           
Logger logger = Logger.getLogger("com.google.api.client");
logger.setLevel(Level.ALL);
logger.addHandler(consoleHandler);  
            
Logger lh = Logger.getLogger("httpclient.wire.header");
lh.setLevel(Level.ALL);
lh.addHandler(consoleHandler);
            
Logger lc = Logger.getLogger("httpclient.wire.content");
lc.setLevel(Level.ALL);
lc.addHandler(consoleHandler);

Logger gl = Logger.getLogger("io.grpc");
gl.setLevel(Level.FINE);
gl.addHandler(consoleHandler);

Setting API Key

String API_KEY = "...";
Oauth2 service = new Oauth2.Builder(httpTransport, jsonFactory, credential)
    .setApplicationName("oauth client")
    .setOauth2RequestInitializer(new Oauth2RequestInitializer(API_KEY))    
    .build();

Setting Request Parameter

Oauth2 service = new Oauth2.Builder(httpTransport, jsonFactory, credential)
    .setApplicationName("oauth client")
    .setOauth2RequestInitializer(new Oauth2RequestInitializer(){
        @Override
        public void initializeOauth2Request(Oauth2Request<?> request) {
            request.setPrettyPrint(true);
        }
    })      
    .build();

Credential store

See documentatin on Drive

Exponential Backoff

See ExponentialBackOff

import com.google.api.client.util.ExponentialBackOff;

final GoogleCredential credential = GoogleCredential.getApplicationDefault(httpTransport,jsonFactory).createScoped(Arrays.asList(Oauth2Scopes.USERINFO_EMAIL));

Oauth2 service = new Oauth2.Builder(httpTransport, jsonFactory, new HttpRequestInitializer() {
                public void initialize(HttpRequest request) throws IOException {
                    request.setContentLoggingLimit(0);
                    request.setCurlLoggingEnabled(false);
                    credential.initialize(request);
                    ExponentialBackOff backoff = new ExponentialBackOff.Builder()
                    .setInitialIntervalMillis(500)
                    .setMaxElapsedTimeMillis(900000)
                    .setMaxIntervalMillis(6000)
                    .setMultiplier(1.5)
                    .setRandomizationFactor(0.5)
                    .build();
                  request.setUnsuccessfulResponseHandler(new HttpBackOffUnsuccessfulResponseHandler(backoff));
                }
            })                  
            .setApplicationName("oauth client")
            .build();

or using Cloud Libraries

import com.google.api.gax.retrying.RetrySettings;

        Storage storage = StorageOptions.newBuilder()
            .setCredentials(myprovider.getCredentials())
            .setRetrySettings(ServiceOptions.getDefaultRetrySettings())
            .build()
            .getService();

Google API Go

DefaultTokenSource

Appengine

Under auth/gae/goapp. Runs a simple GAE application using both Application DefaultCredentials and AppEngineTokenSource. To deploy:

mkdir extra
export GOPATH=/path/to/where/the/extra/folder/is
go get golang.org/x/oauth2
go get google.golang.org/appengine/...
go get google.golang.org/cloud/compute/...
go get google.golang.org/api/oauth2/v2

# vm: false
google-cloud-sdk/go_appengine/goapp serve src/app.yaml
google-cloud-sdk/go_appengine/goapp deploy src/app.yaml

# vm: true
uncomment appengine.Main in func main
gcloud app run src/app.yaml
gcloud app deploy src/app.yaml --version 1 --set-default

ComputeEngine

Under auth/compute/goapp. Runs a simple application using both Application DefaultCredentials and ComputeTokenSource. To deploy:

go get golang.org/x/net/context
go get golang.org/x/oauth2/google
go get google.golang.org/cloud/compute/...
go get google.golang.org/api/oauth2/v2
go run src/main.go

Service Account JSON File

Under auth/service/goapp. Runs a simple application using both Application DefaultCredentials and directly reading JWTConfigFromJSON. To deploy:

go get golang.org/x/net/context
go get golang.org/x/oauth2/google
go get google.golang.org/cloud/compute/...
go get google.golang.org/api/oauth2/v2
go run src/main.go

UserFlow

Under auth/userflow/goapp. Runs a simple webflow application to acquire user consent for GoogleAPIs. This particular userflow launches a link URL and expects the authorization token to get entered (installed application).

go get golang.org/x/net/context
go get golang.org/x/oauth2/google
go get google.golang.org/cloud/compute/...
go get google.golang.org/api/oauth2/v2
go run src/main.go

Misc

Setting API Key

import "google.golang.org/api/googleapi/transport"
apiKey :="YOUR_API_KEY"
client.Transport = &transport.APIKey{ 
    Key: apiKey, 
}

Validating id_token

src, err := google.DefaultTokenSource(oauth2.NoContext, oauthsvc.UserinfoEmailScope)
if err != nil {
    log.Fatalf("Unable to acquire token source: %v", err)
}
tok, err := src.Token()
if err != nil {
    log.Fatalf("Unable to acquire token: %v", err)
}
log.Printf("id_token: " , tok.Extra("id_token").(string))

Also see

Credential store

See oauth2.ReuseTokenSource

src, err := google.DefaultTokenSource(oauth2.NoContext, oauthsvc.UserinfoEmailScope)
if err != nil {
   log.Fatalf("Unable to acquire token source: %v", err)
}
    
tok, err := tokenFromFile("credential.token")
src = oauth2.ReuseTokenSource(tok,src)
tokenval, err := src2.Token()
if err != nil {
    log.Fatalf("Token can't be read")
} else {
    log.Printf("token %v\n", tokenval.AccessToken)
}
    
client := oauth2.NewClient(context.Background(), src)
svc, err := oauthsvc.New(client)
if err != nil {
    log.Fatalf("ERROR: ", err)
}
...
...
func saveToken(file string, token *oauth2.Token) {
    f, err := os.Create(file)
    if err != nil {
        log.Printf("Warning: failed to cache oauth token: %v", err)
        return
    }
    defer f.Close()
    json.NewEncoder(f).Encode(token)
}

func tokenFromFile(file string) (*oauth2.Token, error) {
    f, err := os.Open(file)
    if err != nil {
        return nil, err
    }
    defer f.Close()
    t := new(oauth2.Token)
    err = json.NewDecoder(f).Decode(t)
    return t, err
}

Logging

The follwoing example of trace http logging wraps the Transport around a logging version: LogTransport.

This example also shows how the API_KEY could get constructed although this particular API (oauth2/v2) does not need or expect an api_key.

package main
import (
    "golang.org/x/oauth2"
    "golang.org/x/oauth2/google"    
    "log"   
    oauthsvc "google.golang.org/api/oauth2/v2"
    "google.golang.org/api/googleapi/transport" 
    "net/http"
)
const (
    api_key   = "YOUR_API_KEY"
)
func Auth() {
    src, err := google.DefaultTokenSource(oauth2.NoContext, oauthsvc.UserinfoEmailScope)
    if err != nil {
        log.Fatalf("Unable to acquire token source: %v", err)
    }
    transport := &transport.APIKey{
    //  Key:       api_key,
        Transport: &logTransport{http.DefaultTransport},
    }
    client := &http.Client{
        Transport: &oauth2.Transport{
            Source: src,
            Base:   transport,
        },
    }           
    service, err := oauthsvc.New(client)
    if err != nil {
        log.Fatalf("Unable to create oauth2 service client: %v", err)
    }
    ui, err := service.Userinfo.Get().Do()
    if err != nil {
        log.Fatalf("ERROR: ", err)
    }   
    log.Printf("UserInfo: %v", ui.Email)
}

Google API NodeJS

google.auth.getApplicationDefault

Appengine

Under auth/gae/nodeapp. Runs a simple GAE application using Application DefaultCredentials. To deploy:

gcloud app deploy app.yaml

ComputeEngine

Runs sample on ComputeEngine. Requires the userinfo scope enabled on the compute engine instance.

npm install
npm start

Service Account JSON File

Under auth/service/nodeapp. Runs a simple application using both Application DefaultCredentials and directly reading JSON KEY file.

UserFlow

Under auth/userflow/nodeapp. Runs a simple webflow application to acquire user consent for GoogleAPIs. This particular userflow provides a link URL and expects the authorization token to get entered (installed application).

Misc

Setting API Key

var service = google.oauth2({ 
      version: 'v2', 
      auth: authClient, 
      params: { key: 'YOUR_API_KEY'}
});

Logging

export NODE_DEBUG=request

Google API C#

.NET packages downloadable from NuGet. Full end-to-end example of all the auth modes available here for CloudStorage

Google API .NET Library

Appengine

GAE Standard does not support .NET as a runtime. However, you can deploy your application to GAE Flex if you run .NET Core on Linux. See the following sample that runs a .NET webapp in Flex: .NET on GCP. Note: Google APIs do not support .NET Core (coreCLR) yet. At the time of writing, they only supports upto .NET Framework 4.5.1. This means you cannot use Google APIs from within a Container. There are some ports to coreCLR but they are not officially supported.

ComputeEngine

Under auth/compute/dotnet. Runs a simple application using both Application DefaultCredentials and ComputeCredential.

Service Account JSON File

Under auth/service/dotnet. Runs a simple application using both Application DefaultCredentials using a JSON Certificate and by directly reading in the PKCS12 Certificate file. If the GOOGLE_APPLICATION_CREDENTIALS variable is set to point to the JSON file, the applicationDefault profile will also read the JSON file (otherwise, it will attempt to pick up the gcloud credentials).

UserFlow

Under auth/userflow/dotnet. Runs a simple webflow application to acquire user consent for GoogleAPIs. This particular userflow launches provides a link URL and expects user consent on the browser.

Credential store

Credentials from the GoogleAPIs userflow is usually stored at

Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData));
or c:\Users\%USER%\AppData\Roaming\Google.Apis.Auth

Using API through Proxy

gRPC clients support http_proxy parameter:

https://github.com/grpc/grpc/blob/master/doc/environment_variables.md

The following is curated from: https://kzhendev.wordpress.com/2015/04/28/accessing-google-apis-through-a-proxy-with-net/

using System.Net;
using System.Net.Http;
using System.Security.Cryptography.X509Certificates;

using Google.Apis.Auth.OAuth2;
using Google.Apis.Oauth2.v2;
using Google.Apis.Services;
using Google.Apis.Http;


            string CREDENTIAL_FILE_PKCS12 = "c:\\your_cert.p12"; 
            string serviceAccountEmail = "your_svc_account@project.iam.gserviceaccount.com";
            var certificate = new X509Certificate2(CREDENTIAL_FILE_PKCS12, "notasecret",X509KeyStorageFlags.Exportable);
            ServiceAccountCredential credential = new ServiceAccountCredential(
               new ServiceAccountCredential.Initializer(serviceAccountEmail)
               {
                   Scopes = new[] { Oauth2Service.Scope.UserinfoEmail },
                   HttpClientFactory = new ProxySupportedHttpClientFactory()
               }.FromCertificate(certificate));


            var service = new Oauth2Service(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = "Oauth2 Sample",
                HttpClientFactory = new ProxySupportedHttpClientFactory()
            });



public class ProxySupportedHttpClientFactory : HttpClientFactory
{
    protected override HttpMessageHandler CreateHandler(CreateHttpClientArgs args)
    {

        ICredentials credentials = new NetworkCredential("user1", "user1");

        var proxy = new WebProxy("http://192.168.1.6:3128", true, null, credentials);

        var webRequestHandler = new WebRequestHandler()
        {
            UseProxy = true,
            Proxy = proxy,
            UseCookies = false
        };

        return webRequestHandler;
    }
}

Google Cloud Platform Samples

samples provided as-is without warranty

Application Default Credentials

GoogleLibraries

Google Cloud Client Libraries

Cloud Python

Iterators

Cloud Java

Proxy Server Settings

Credential Providers

Async Futures

Cloud Go

Exponential Backoff

Cloud Node

Cloud C#

gRPC Environment Variables

Google API Client Library for Python

Google API Python

Appengine

ComputeEngine

Service Account File

Userflow

Misc

Setting API Key

Logging

Appengine Cloud Endpoints

Credential store

ID Token from Service Account JSON Signed by Google

Returns JSON with a JWT signed by Google:

Google API Java

Appengine

ComputeEngine

Service Account File

UserFlow

Misc

Logging

Setting API Key

Setting Request Parameter

Credential store

Exponential Backoff

Google API Go

Appengine

ComputeEngine

Service Account JSON File

UserFlow

Misc

Setting API Key

Validating id_token

Credential store

Logging

Google API NodeJS

Appengine

ComputeEngine

Service Account JSON File

UserFlow

Misc

Setting API Key

Logging

Google API C#

Appengine

ComputeEngine

Service Account JSON File

UserFlow

Credential store

Using API through Proxy

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