Prerequisite
You need the following content:
1. A Google account, such as from Gmail. If you do not, please register at Google Account signup site.
2. A new or existing Google Developer console project. If you don't have an existing project, create a new project in Google Developer console.
3. Two cloud Apis:google Cloud Storage and Google Cloud Storage JSON APIs available for your project. To do this, select your project and make the cloud Storage APIs valid.
4. A cloud Storage bucket. See Using Storage buckets for more information.
Using storage buckets
The simplest way to use the cloud Storage bucket in App engine is to use the default bucket. An app Engine default bucket does not need to be reactivated, configured, licensed, or required for your app to start charging. Because it has a free quota.
Use the default bucket
1. Determine if your app has created a default bucket.
A. Browse to the app Engine Admin console and select your app.
B. Select Apply settings (Application Settings) in the left navigation bar.
C. If your app has a default bucket, the app Settings page will contain a cloud Storage bucket label, and the bucket name is listed below. The typical default bucket name is <app_id>.appspot.com,<app_id> is your app ID.
2. If your app does not have a default bucket, create one:
A. Browse to the app Engine Admin console and select your app.
B. Select app settings in the left navigation bar and scroll down to the bottom of the page until cloud integration.
C. Click Create and wait for the bucket to be created. This bucket has been created and ready to use.
Use non-default buckets
You don't want to use the default bucket, and if you use a non-default bucket, you have to let your app start charging and you no longer have a free quota.
1. Browse the Google Developers console and open your project in the console.
2. If you haven't created a paid user yet
A. Click the gear icon in the upper-right corner
B. Click the billing accounts->new Billing account and follow the prompts to create a new pay-per.
3. Click the gear icon on the right and click Project Billing setting->enable Billing.
4. Select the paid account you wish to use and click OK to make it valid.
5. Go back to your project and click Storage->cloud storage->storage browser->create a bucket on the left navigation bar to create the bucket. This bucket has been created and ready to use.
Note: You can use the app Identity Getdefaultgcsbucketname method to find the name programmatically.
Note: The above instructions use the old version of Google developers Console.
Activating Google Cloud Storage