Gcloud aims to make authentication as simple as possible. Google Cloud requires a Project ID and Service Account Credentials to connect to the APIs. To create a service account:
- Visit the Google Developers Console.
- Create a new project or click on an existing project.
- Navigate to APIs & auth > APIs section and turn on the following APIs (you may need to enable billing in order to use these services):
- Google Cloud Datastore API
- Google Cloud Storage
- Google Cloud Storage JSON API
- Navigate to APIs & auth > Credentials and then:
- If you want to use a new service account, click on Create new Client ID and select Service account. After the account is created, you will be prompted to download the JSON key file that the library uses to authorize your requests.
- If you want to generate a new key for an existing service account, click on Generate new JSON key and download the JSON key file.
You will use the Project ID and JSON file to connect to services with gcloud.
Gcloud aims to make authentication as simple as possible, and provides several mechanisms to configure your system without providing Project ID and Service Account Credentials directly in code.
Project ID is discovered in the following order:
- Specify project ID in code
- Discover project ID in environment variables
- Discover GCE project ID
Credentials are discovered in the following order:
- Specify credentials in code
- Discover credentials path in environment variables
- Discover credentials JSON in environment variables
- Discover credentials file in the Cloud SDK's path
- Discover GCE credentials
While running on Google Compute Engine no extra work is needed. The Project ID and Credentials and are discovered automatically. Code should be written as if already authenticated.
The Project ID and Credentials JSON can be placed in environment variables instead of declaring them directly in code. Each service has its own environment variable, allowing for different service accounts to be used for different services. The path to the Credentials JSON file can be stored in the environment variable, or the Credentials JSON itself can be stored for environments such as Docker containers where writing files is difficult or not encouraged.
Here are the environment variables that Datastore checks for project ID:
- DATASTORE_PROJECT
- GCLOUD_PROJECT
Here are the environment variables that Datastore checks for credentials:
- DATASTORE_KEYFILE - Path to JSON file
- GCLOUD_KEYFILE - Path to JSON file
- DATASTORE_KEYFILE_JSON - JSON contents
- GCLOUD_KEYFILE_JSON - JSON contents
This option allows for an easy way to authenticate during development. If credentials are not provided in code or in environment variables, then Cloud SDK credentials are discovered.
To configure your system for this, simply:
- Download and install the Cloud SDK
- Authenticate using OAuth 2.0
$ gcloud auth login
- Write code as if already authenticated.
NOTE: This is not recommended for running in production. The Cloud SDK should only be used during development.
If you're having trouble authenticating open a Github Issue to get help. Also consider searching or asking questions on StackOverflow.