identity

Use the identity API to get an OAuth2 authorization code or access token, which an extension can then use to access user data from a service which supports OAuth2 access (such as a Google or a Facebook account).

Details of how the OAuth2 flow works differ from one service provider to another, so to use this API with a particular service provider, you'll need to consult their documentation. For example:

• https://developers.google.com/identity/protocols/OAuth2UserAgent
• https://developer.github.com/v3/oauth/

The identity API provides the identity.launchWebAuthFlow() function. This authenticates the user with the service, if necessary, and asks the user to authorize the extension to access data, if necessary. The function completes with an access token or authorization code, depending on the provider.

The extension then completes the OAuth2 flow to get a validated access token, and can then use this in HTTP requests to access the user's data according to the authorization the user gave.

To use this API, you must have the "identity" API permission.

Setup

There's some setup you must do before publishing your extension.

Getting the redirect URL

The redirect URL represents the end point of identity.launchWebAuthFlow(), in which the access token or authorization code is delivered to the extension.

You can get a redirect URL by calling identity.getRedirectURL(). This function derives a redirect URL from the add-on's ID, so if you want to use it, you should probably set your add-on's ID explicitly using the applications key (otherwise, each time you temporarily install the add-on, you'll get a different redirect URL).

You don't have to use the redirect URL returned by identity.getRedirectURL(): you can supply your own, and it can be anything that the service will redirect to. However, it should use a domain that you control.

You'll use the redirect URL in two places:

• supply it when registering your extension as an OAuth2 client
• pass it into identity.launchWebAuthFlow(), as a URL parameter added to that function's url argument.

Registering your extension

Before you can use OAuth2 with a service provider, you must register the extension with the provider as an OAuth2 client.

This will tend to be specific to the service provider, but in general it means creating an entry for your extension on the provider's website. In this process you will supply your redirect URL, and receive a client ID (and sometimes also a secret). You'll need to pass both of these into identity.launchWebAuthFlow().

Functions

identity.getRedirectURL()

Gets the redirect URL.

identity.launchWebAuthFlow()

Launches WAF.

Browser compatibility

Chrome incompatibilities

None.

Example extensions

• google-userinfo

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