google-authenticator-util

Google authenticator tool for backend development / automation

How to setup

Create a google oAuth2 credentials

• Go to https://console.developers.google.com/apis/credentials, and under your project create the oAuth2 credentials with an Authorised redirect URI of http://mydomain/oauth2callback (Recommended is http://localhost:port/oauth2callback) And type of Web application
• Download the credentials after creation, in order to re-use later in the code.
• Authorize your third party app to have access to your project, you need to only do it once.

First token generation

In the first time, you don't have a token at all and you will to verify the auth URL using a browser. The following code will do it for you:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2'],
    username: 'your email address username (before the @)',
    password: 'your email address password'
});
const oAuth2 = await authenticator.authorize();

After the first execution of the code, the token will be generated in tokens folder by default and with a name of your-client-id-token.json. After the token is generated, it is recommended to remove the username and password parameters, they are no longer necessary.

How to reuse your token

After first token generation, you can re-use your token in the ways.

Existing token file

After first token was generated, you no longer need to pass the username and password parameters. Your code should look like:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2']
});
const oAuth2 = await authenticator.authorize();

Existing token JS object

If you don't want to store a token file, you can always re-use the existing token as a JS object inside the code:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2'],
},{
    tokenOptions: {
        token: {
            access_token: 'your access token',
            refresh_token: 'your refresh token',
            scope: ['scope 1', 'scope 2'],
            token_type: 'the type of the token',
            expiry_date: 1315241515
        }
    }
});
const oAuth2 = await authenticator.authorize();

Now you can remove the generated token file and keep authenticating.

oAuth2 Client

The strong point of this module, is it's pre-build easy to use oAuth2 client. To get a built oAuth2 Client without knowing too much, do the following in your code:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2'],
    username: 'your email address username (before the @)', //only needed for first authentication
    password: 'your email address password' //only needed for first authentication
});
const oAuth2 = await authenticator.authorize();

Now the oAuth2 variable holds the oAuth2 object you need.

GMAIL Client

You can use the GMAIL Client used in the module, in order to perform your async actions:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2'],
    username: 'your email address username (before the @)', //only needed for first authentication
    password: 'your email address password' //only needed for first authentication
});
const oAuth2 = await authenticator.authorize();
const gmail = authenticator.getGmailClient();
const messages = await gmail.users.messages.list({
    userId: 'me',
    labelIds: parameters.labelIds,
    auth: oAuth2,
    q: `subject: ${parameters.subject}`
});

Or you can use the original gmail client:

const authenticator = new GoogleAuthenticator({
    clientId: 'your client ID',
    clientSecret: 'your client secret',
    scope: ['scope 1', 'scope 2'],
    username: 'your email address username (before the @)', //only needed for first authentication
    password: 'your email address password' //only needed for first authentication
});
const oAuth2 = await authenticator.authorize();
const gmail = google.gmail('v1');
const messages = await gmail.users.messages.list({
    userId: 'me',
    labelIds: parameters.labelIds,
    auth: oAuth2,
    q: `subject: ${parameters.subject}`
});