Get image from Google Cloud Storage in App Engine - google-app-engine

I am trying to get an image in my App Engine backend and every time I try to get it I get the following error
com.google.api.client.googleapis.json.GoogleJsonResponseException: 503 Service Unavailable
{
"code": 503,
"errors": [
{
"domain": "global",
"message": "java.io.IOException: The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.",
"reason": "backendError"
}
],
"message": "java.io.IOException: The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information."
}
Now it was my understanding that when making a request from App Engine backend that the Application Default Credentials was sufficient enough to do it.
The Application Default Credentials provide a simple way to get
authorization credentials for use in calling Google APIs.
They are best suited for cases when the call needs to have the same
identity and authorization level for the application independent of
the user. This is the recommended approach to authorize calls to
Google Cloud APIs, particularly when you're building an application
that is deployed to Google App Engine or Google Compute Engine virtual
machines.
taken from here
This is how I am trying to get the image using the Java API
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
GoogleCredential credential = GoogleCredential.getApplicationDefault();
if(credential.createScopedRequired()){
credential = credential.createScoped(StorageScopes.all());
}
Storage.Builder storageBuilder = new Storage.Builder(httpTransport,new JacksonFactory(),credential);
Storage storage = storageBuilder.build();
Storage.Objects.Get getObject = storage.objects().get("myBucket", name);
ByteArrayOutputStream out = new ByteArrayOutputStream();
getObject.getMediaHttpDownloader().setDirectDownloadEnabled(false);
getObject.executeMediaAndDownloadTo(out);
byte[] oldImageData = out.toByteArray();
out.close();
ImagesService imagesService = ImagesServiceFactory.getImagesService();
Image oldImage = ImagesServiceFactory.makeImage(oldImageData);
Transform resize = ImagesServiceFactory.makeResize(width, height);
return imagesService.applyTransform(resize, oldImage);
am I just using the credentials wrong or can I not use the application default credentials?

If you want to access your Google Cloud Storage data from App Engine. You should be using the Google Cloud Storage Client Library
Github Project

Related

Authentication using Google Service Account in a flask app and deploying on Google App Engine

Below are my requirements.
Develop a flask app.
Use collections in the firebase in the app.
Deploy this app on Google App Engine using a standard service account
What I have done.
Created a service account
Downloaded the corresponding credentials json; I am calling it as key.json
written a main.py
cred = credentials.Certificate('key.json')
default_app = initialize_app(cred)
db = firestore.client()
user_ref = db.collection_group('Users')
#app.route('/', methods=['GET'])
def home():
return "<h1>Welcome to my first app</h1>"
#app.route('/users', methods=['GET'])
def getUsers():
try:
result = [user.to_dict() for user in user_ref .stream()]
return jsonify(result), 200
except Exception as e:
result = { "message:"failed"}
return jsonify(result), 500
I have tested this locally and also on deployed on Google App Engine.
In both the cases, key.json was in the same directory as the code.
I have verified that if this key.json is modified to store wrong data, then /users endpoint won't work and gives me a 500 error.
So far so good. I want to know if this is even the right approach.
I want the key.json authentication to applied even for the root / endpoint.
i.e., if the user supplies a valid key.json, only then the Welcome to my first app should be displayed.
Else, Unauthorized user message needs to be displayed.
As mentioned by #Gaefan and #DishantMakwana, as well as in this documentation:
An API key only identifies the application and doesn't require user authentication. It is sufficient for accessing public data.
So in order to authenticate/authorize your users you should reconsider your strategy. I would recommend you to follow the instructions in the Authenticating as an end user Documentation.
I have found that we can use Google Cloud Endpoints for API management. Works as a charm.

Google Cloud Pubsub authentication error from App Engine

We're having trouble publishing messages to a Google Cloud PubSub topic on Google AppEngine. Using the Application Default credentials works perfect locally. But once it's deployed on Google AppEngine it gives the following error:
<HttpError 403 when requesting https://pubsub.googleapis.com/v1/projects/our-project-id/topics/our-topic:publish?alt=json returned "The request cannot be identified with a project. Please pass a valid API key with the request.">
I would assume that it's will use the service account of app engine to access the PubSub API. Here is the code we used to create the credentials.
credentials = GoogleCredentials.get_application_default()
if credentials.create_scoped_required():
credentials = credentials.create_scoped(['https://www.googleapis.com/auth/pubsub'])
http = httplib2.Http()
credentials.authorize(http)
pubsub_service = build('pubsub', 'v1', http=http)
The error is thrown when publishing the actual message to PubSub.
pubsub_service.projects().topics().publish(topic="projects/out-project-id/topics/out-topic", body = { 'messages' : [ { 'data': base64.b64encode(request.get_data()) }]}).execute()
Not that the same flow works doing API call's to "BigQuery", so it's not a general Google API problem. It seems to be specific to PubSub...
It's a rare case of the service account without project id embedded in it. We fixed your service account and you should be good to go now. Sorry for the trouble.

How can you get the Google+ Profile of the current user when using Google Cloud Endpoint's (Java) built in authentication?

My Setup
Backend: Google App Engine (Java) w/ Google Cloud Endpoints using Endpoint's built in authentication
Frontend: AngularJS web app
Problem
I need to get the Google+ profile for my users. The keyword "me" can generally be used to get the current user's Google+ profile, however since all the authentication, in Google Cloud Endpoints, is done under the hood, I don't see anyway to get credentials, nor a token, for the current user. All you get it the com.google.appengine.api.users.User object.
Is there any way to get user credentials, or the access token, when using Google Cloud Endpoint's built in authentication?
Note: Google+ profile ID is different form Google account ID.
Possible Solution
I could just use the Google+ JS client with the keyword "me" and have the user send their Google+ ID and then subsequently store it and tie it to their Google Account ID, but this would be incredible insecure as the user could hack their way to sending the ID of any Google+ account.
It is possible to get the user access token when using Google Cloud Endpoint's built in authentication.
Add the parameter HttpServletRequest request to your Google Cloud endpoint as shown below. This will allow you to get the raw request.
You will then need to retreive the header called Authentication. This will get a Bearer access token that will allow you to build credentials to impersonate the authenticated user.
Next you will use that Bearer access token to build a com.google.api.client.googleapis.auth.oauth2.GoogleCredential object. You will need this to build the Plus service.
Use the Plus builder to build a Plus service object with the credential you just created.
Sample Code
#ApiMethod(path = "myPath")
public void myEndpoint(HttpServletRequest request, ParmOne paramOne, ...) throws OAuthRequestException {
if (user == null) {
throw new OAuthRequestException("Authentication error!");
}
GoogleCredential credentialAsUser = new GoogleCredential().setAccessToken(request.getHeader("Authorization").substring(7)); // Start string at index position 7 to remove prefix "Bearer" from token.
Plus plus = new Plus.Builder(new UrlFetchTransport(), new JacksonFactory(), credentialAsUser).setApplicationName("my-app").build();
Person profile = plus.people().get("me").execute();
}
Documentation
The Java docs for the Google Plus client can be found here.
The Java docs for instructions on creating Google credentials can be found here.
Additional Answer for Android Clients
Problem
In addition to the Marc's answer it is important that the GoogleCredentials-Object needs an access_token in the request-header.
If you call the endpoint with your apiExplorer or a javascript endpoint, this token is already served in the Authorization-header. But if you follow the docs for an android client your requests header contains an id_token, so GoogleCredentials.setAccessToken does not work.
Solution
To change the type of authorization to an access_token simply create your GoogleAccountCredential-Object in Android with usingOAuth2 instead of usingAudience.
Example
Replace this code in your Android App
credential = GoogleAccountCredential.usingAudience(this,
"server:client_id:1-web-app.apps.googleusercontent.com");
with this
credential = GoogleAccountCredential.usingOAuth2(this,
Collections.singleton(Scopes.PLUS_LOGIN));
and send it to your Api, as it is explained by the documentation
Helloworld.Builder helloWorld = new Helloworld.Builder(AppConstants.HTTP_TRANSPORT,
AppConstants.JSON_FACTORY,credential);

Using AppIdentityCredential with Google Drive API

I am using Google App Engine Identity to access Google Drive API of a Google Apps user.
I have inserted GAE URL in Manage API client access in Google Apps, with the right scope.
AppIdentityCredential credential = new AppIdentityCredential(Arrays.asList(DriveScopes.DRIVE_FILE));
HttpTransport httpTransport = new NetHttpTransport();
JsonFactory jsonFactory = new JacksonFactory();
Drive service = new Drive.Builder(httpTransport, jsonFactory, credential).build();
I get this error:
com.google.appengine.repackaged.org.apache.http.impl.client.DefaultRequestDirector handleResponse
WARNING: Authentication error: Unable to respond to any of these challenges: {authsub=WWW-Authenticate: AuthSub realm="https://www.google.com/accounts/AuthSubRequest" allowed-scopes="https://www.googleapis.com/auth/drive,https://www.googleapis.com/auth/docs,https://www.googleapis.com/auth/drive.file,https://www.googleapis.com/auth/drive.readonly,https://www.googleapis.com/auth/drive.metadata.readonly"}
An error occurred: com.google.api.client.googleapis.json.GoogleJsonResponseException: 401 OK
{
"code" : 401,
"errors" : [ {
"domain" : "global",
"location" : "Authorization",
"locationType" : "header",
"message" : "Invalid Credentials",
"reason" : "authError"
} ],
"message" : "Invalid Credentials"
}
Is it necessary to enable GAE application in API Client access in Google Apps? If not, how I authorise GAE app to gain acess to an API Scope?
Is possible to test GAE Identity in Local / Eclipse?
Summarizing, what is wrong or lack?
You can not debug AppEngine Credentials locally. The only way to debug is to use different credentials (AppEngine for production and Key-based service account locally). It will require to write different code for local and production environment.
You need to add your appengine service accounts to Team. If you use custom Google Apps domain for your project than you will need to create email group in your custom domain and add this group. All service accounts should be added to this group.
Consider adding the scopes it tries to authenticate against.
I had the same error in my code and ended up solving in by adding the drive.file scope.
Two important steps
Get the Application Default Credentials Service account JSON file.
Set GOOGLE_APPLICATION_CREDENTIALS environment variable with the path of the JSON file. Example: GOOGLE_APPLICATION_CREDENTIALS=c:/myFolder/my.jsonfile
FYI:
https://developers.google.com/identity/protocols/application-default-credentials

google app script consumer with google appEngine Provider (Oauth)

I could get an Oauth conexion between GAS and GAE.
I built a Google Gadget which needs some data from my datastore application, it has 3 end points to finally get an access token.
http//[myapp].appspot.com/_ah/OAuthGetRequestToken
http//[myapp].appspot.com/_ah/OAuthAuthorizeToken
http//[myapp].appspot.com/_ah/OAuthGetAccessToken
In GAS side i have the tipical function to get an access token.
function oauthTokenFetch(){
var oAuthConfig = UrlFetchApp.addOAuthService("myAppName");
oAuthConfig.setAccessTokenUrl("https://<myApp>appspot.com/_ah/OAuthGetAccessToken");
oAuthConfig.setRequestTokenUrl("https://<myApp>.appspot.com/_ah/OAuthGetRequestToken");
oAuthConfig.setAuthorizationUrl("https://<myApp>.appspot.com/_ah/OAuthAuthorizeToken");
oAuthConfig.setConsumerKey("<myApp>.appspot.com");
oAuthConfig.setConsumerSecret("myConsumerSecret");
var requestData = {
"method": "GET",
"oAuthServiceName": "myAppName",
"oAuthUseToken": "always"
};
try {
var response2=UrlFetchApp.fetch("http://<myApp>.appspot.com/test/oauth",requestData);
Logger.log(response2.getResponseCode());
}catch(exception){
Logger.log(exception);
}
If i revoked the access token on google accounts, it isn't able for getting another one, the popup which grants the authorization don't appears ... i have to copy the google gadget and do the authorization again.
Somebody have a Solution?
There currently isn't a method to allow you to revoke or remove an OAuth token in a script. It looks like you already filed a bug/feature request on the topic, and we'll follow up there.

Resources