# OAuth made easy

## Authentication in two lines

OAuth2.0 is complex and difficult to start with. To make it more simple, PyDrive makes all authentication into just two lines.

    from pydrive.auth import GoogleAuth

    gauth = GoogleAuth()
    # Create local webserver and auto handles authentication.
    gauth.LocalWebserverAuth()

To make this code work, you need to download the application configurations file from APIs Console. Take a look at quickstart for detailed instructions.

LocalWebserverAuth() is a built-in method of GoogleAuth which sets up local webserver to automatically receive authentication code from user and authorizes by itself. You can also use CommandLineAuth() which manually takes code from user at command line.

## Automatic and custom authentication with settings.yaml

Read this section if you need a custom authentication flow, such as silent authentication on a remote machine. For an example of such a setup have a look at Sample settings.yaml.

OAuth is complicated and it requires a lot of settings. By default, when you don’t provide any settings, PyDrive will automatically set default values which works for most of the cases. Here are some default settings.

- Read client configuration from file client_secrets.json
- OAuth scope: `https://www.googleapis.com/auth/drive`
- Don’t save credentials
- Don’t retrieve refresh token

However, you might want to customize these settings while maintaining two lines of clean code. If that is the case, you can make settings.yaml file in your working directory and PyDrive will read it to customize authentication behavior.

These are all the possible fields of a settings.yaml file:

    client_config_backend: {{str}}
    client_config_file: {{str}}
    client_config:
      client_id: {{str}}
      client_secret: {{str}}
      auth_uri: {{str}}
      token_uri: {{str}}
      redirect_uri: {{str}}
      revoke_uri: {{str}}

    save_credentials: {{bool}}
    save_credentials_backend: {{str}}
    save_credentials_file: {{str}}

    get_refresh_token: {{bool}}

    oauth_scope: {{list of str}}

Fields explained:

client_config_backend (str):
| From where to read client configuration(API application settings such as client_id and client_secrets) from. Valid values are ‘file’ and ‘settings’. Default: ‘file’. Required: No.
client_config_file (str):
| When client_config_backend is ‘file’, path to the file containing client configuration. Default: ‘client_secrets.json’. Required: No.
client_config (dict):
| Place holding dictionary for client configuration when client_config_backend is ‘settings’. Required: Yes, only if client_config_backend is ‘settings’
client_config[‘client_id’] (str):
| Client ID of the application. Required: Yes, only if client_config_backend is ‘settings’
client_config[‘client_secret’] (str):
| Client secret of the application. Required: Yes, only if client_config_backend is ‘settings’
client_config[‘auth_uri’] (str):
| The authorization server endpoint URI. Default: ‘https://accounts.google.com/o/oauth2/auth‘. Required: No.
client_config[‘token_uri’] (str):
| The token server endpoint URI. Default: ‘https://accounts.google.com/o/oauth2/token‘. Required: No.
client_config[‘redirect_uri’] (str):
| Redirection endpoint URI. Default: ‘urn:ietf:wg:oauth:2.0:oob‘. Required: No.
client_config[‘revoke_uri’] (str):
| Revoke endpoint URI. Default: None. Required: No.
save_credentials (bool):
| True if you want to save credentials. Default: False. Required: No.
save_credentials_backend (str):
| Backend to save credentials to. ‘file’ is the only valid value for now. Default: ‘file’. Required: No.
save_credentials_file (str):
| Destination of credentials file. Required: Yes, only if save_credentials_backend is ‘file’.
get_refresh_token (bool):
| True if you want to retrieve refresh token along with access token. Default: False. Required: No.
oauth_scope (list of str):
| OAuth scope to authenticate. Default: [‘https://www.googleapis.com/auth/drive‘]. Required: No.

### Sample settings.yaml

    client_config_backend: settings
    client_config:
      client_id: 9637341109347.apps.googleusercontent.com
      client_secret: psDskOoWr1P602PXRTHi

    save_credentials: True
    save_credentials_backend: file
    save_credentials_file: credentials.json

    get_refresh_token: True

    oauth_scope:
      - https://www.googleapis.com/auth/drive.file
      - https://www.googleapis.com/auth/drive.install

## Building your own authentication flow

You might want to build your own authentication flow. For example, you might want to integrate your existing website with Drive API. In that case, you can customize authentication flow as follwing:

1. Get authentication Url from GetAuthUrl().
2. Ask users to visit the authentication Url and grant access to your application. Retrieve authentication code manually by user or automatically by building your own oauth2callback.
3. Call Auth(code) with the authentication code you retrieved from step 2.

Your settings.yaml will work for your customized authentication flow, too.

Here is a sample code for your customized authentication flow

    from pydrive.auth import GoogleAuth

    gauth = GoogleAuth()
    auth_url = gauth.GetAuthUrl() # Create authentication url user needs to visit
    code = AskUserToVisitLinkAndGiveCode(auth_url) # Your customized authentication flow
    gauth.Auth(code) # Authorize and build service from the code