Login OAuth2 Plugin

The Login OAuth2 Plugin for Grav CMS allows user authentication against an OAuth2 Authentication Provider. This plugin makes use of The League OAuth2 Client

Currently the core plugin supports the following providers:

• Facebook - https://developers.facebook.com/docs/facebook-login/web
• GitHub - https://developer.github.com/apps/building-oauth-apps/creating-an-oauth-app/
• Google - https://developers.google.com/identity/protocols/OpenIDConnect
• Instagram - https://www.instagram.com/developer/authentication/
• LinkedIn - https://developer.linkedin.com/docs/oauth2

It's also possible to extend this plugin an create a new AOauth2 for specific providers.

Callback URL

When you setup your OAuth provider application, you will need to provide a Callback URL. Grav passes this as part of the OAuth2 request process, but it needs to match the configuration on the server side. Typically, when logging in via the the frontend site, the URL will look something like this:

http://yoursite.com/task:callback.oauth2

Where http://yoursite.com is the URL of your Grav-based site. If you are using SSL, then this URL will be:

https://yoursite.com/task:callback.oauth2

If you use the OAuth2 plugin to login to the admin side of your Grav site, your callback URL will look like this:

http://yoursite.com/admin/task:callback.oauth2

Where http://yoursite.com/admin is the URL you use to log into the admin plugin. Again, if you have this under SSL, you would need to use https:// rather than http://. Some OAuth2 providers allow you to use provide multiple callback URLs, and in this case you can use the same application setup with multiple URLs, to work with the site and the admin and potentially http:// and https:// URLs. However, some providers only allow a single callback URL, and in these cases you need to create multiple OAuth2 applications to handle each callback URL.

Installation

Installing the Login OAuth2 plugin can be done in one of two ways. The GPM (Grav Package Manager) installation method enables you to quickly and easily install the plugin with a simple terminal command, while the manual method enables you to do so via a zip file.

GPM Installation (Preferred)

The simplest way to install this plugin is via the Grav Package Manager (GPM) through your system's terminal (also called the command line). From the root of your Grav install type:

bin/gpm install login-oauth2

This will install the Login OAuth2 plugin into your /user/plugins directory within Grav. Its files can be found under /your/site/grav/user/plugins/login-oauth2.

Manual Installation

To install this plugin, just download the zip version of this repository and unzip it under /your/site/grav/user/plugins. Then, rename the folder to login-oauth2. You can find these files on GitHub or via GetGrav.org.

You should now have all the plugin files under

/your/site/grav/user/plugins/login-oauth2

Before configuring this plugin, you should copy the user/plugins/login-oauth2/login-oauth2.yaml to user/config/plugins/login-oauth2.yaml and only edit that copy.

Admin Installation

If you use the admin plugin, you can install directly through the admin plugin by browsing the to Plugins in the sidebar menu and clicking on the Add button.

Configuring the Login OAuth2 plugin is as easy as navigating to the Plugins manager, and editing the configuration options.

Configuration Options

The default configuration and an explanation of available options:

enabled: true

built_in_css: true
button_style: row
require_grav_user: false
save_grav_user: false
store_provider_data: true
default_access_levels:
  access:
    site:
      login: true
default_groups:

providers:
  github:
    enabled: true
    client_id: ''
    client_secret: ''
    options:
      scope: ['user', 'user:email']

  instagram:
    enabled: true
    client_id: ''
    client_secret: ''
    options:
      scope: ['basic', 'likes', 'comments']
      host: 'https://api.instagram.com'

  facebook:
    enabled: true
    app_id: ''
    app_secret: ''
    options:
      scope: ['email', 'public_profile', 'user_hometown']
      graph_api_version: 'v2.10'

  google:
    enabled: true
    client_id: ''
    client_secret: ''
    hd: '*'
    options:
      scope: ['email', 'profile']
      avatar_size: 200

  linkedin:
    enabled: true
    client_id: ''
    client_secret: ''
    options:
      scope: ['r_basicprofile','r_emailaddress']

admin:
  enabled: false
  built_in_css: true
  button_style: row

  providers:
    github:
      enabled: false
      client_id: ''
      client_secret: ''
      options:
        scope: ['user', 'user:email']

    instagram:
      enabled: false
      client_id: ''
      client_secret: ''
      options:
        scope: ['basic', 'likes', 'comments']
        host: 'https://api.instagram.com'

    facebook:
      enabled: false
      app_id: ''
      app_secret: ''
      options:
        scope: ['email', 'public_profile', 'user_hometown']
        graph_api_version: 'v2.10'

    google:
      enabled: false
      client_id: ''
      client_secret: ''
      hd: '*'
      options:
        scope: ['email', 'profile']
        avatar_size: 200

    linkedin:
      enabled: false
      client_id: ''
      client_secret: ''
      options:
        scope: ['r_basicprofile','r_emailaddress']

Server Settings

OAuth2 Providers

GitHub

Instagram

Facebook

Google

Instagram

Note that if you use the admin plugin, a file with your configuration will be saved in the user/config/plugins/login-oauth2.yaml.

Usage

Once properly configured, the functionality of the OAuth2 plugin is simple for the user. The login form will display enabled OAuth2 Providers, and the user can click on one which will then redirect them to the provider to authenticate and accept the permissions requested via the scope fields. Upon completion of this process, the user will then be redirected back to the site where they will now be logged in.

OAuth2 User Data

Any user data available via the scope provider options will be retrieved. Core fields like username, and email will be stored on the Grav user object, and anything else that is provider-specific can be optionally stored as well. By default, the Grav user object is not persisted to a physical Grav account YAML file, instead it's just kept in session temporarily.

Storing Grav User

By default the OAuth2 plugin does not store any local user information. Upon successfully authenticating against the OAuth2 user, a user is created and is available during the session. However, upon returning, the user must re-authenticate and the OAuth2 data is retrieved again.

If you want to be able to set user data (extra fields, or specific user access) for a particular user, you can enable the save_grav_user option, and this will create a local Grav user in the accounts/ folder. This is a local record of the user and attributes can be set here.

NOTE: Any attribute stored under the provider key (e.g. github:) in the user account file will be overwritten by the plugin during the next login. This information is always in sync with latest data from the provider.

Also note that the password will never be stored in the Grav user under accounts/.

OAuth2 to Grav Access Mapping

The OAuth2 plugin provides a flexible way to map your OAuth2 users into Grav.

For Groups and Access mapping to work properly a valid search_dn, query_dn and group_query is required.

The default configuration for default_access_levels.access looks like:

user:
  site:
    login: true

In order for a front-end user to be able to log into a Grav site the minimum of site: [login: true] is required. You can of course configure this with any access settings you wish to provide.

It is not advised to provide any admin access via OAuth2 accounts, but if you wish a particular OAuth user to be able to log into the admin, you should enable the save_grav_user option, so the userdata is persisted as a Grav Account YAML file, and then manually add the desired permissions. These will not be reset to the default values on each login.

NOTE: See the Groups and Permissions Documentation for more information about how Grav permissions work in conjunction with access levels and groups.

Admin Notes

New in version 2.0 is the support for OAuth2 providers to be able to login via the admin. After careful consideration, we decided to provide configuration options for both Site and Admin as there are some providers that need to have a unique OAuth2 Application setup for each unique callback. This is important because by default, Grav uses a different session for both Site and Admin. Therefore you need a unique callback, one that goes to the frontend site, and one to the admin. This means we have to provide a way to have unique application settings for both Site and Admin.

There are some providers such as Discord and GitLab that actually allow for multiple callback URLs to be registered. In this case, simply copy over the same client_id and client_secret for both Site and Admin.

Also, if you have the system.session.split option set to false, you are effectively sharing the session between Site and Admin, and again, you can share the Site configuration, but they need to be entered into both sets of options.

For admin logins to be useful, you need to ensure you set store_grav_user: true (which is not default behavior). This will ensure that when you login, a local accounts .yaml file will be create in user/accounts/ folder. A this point you can manually add the admin access required to log into the admin by directly editing the .yaml file that was auto-created during the login process:

  access:
    admin:
      login: true
      super: true
    site:
      login: true

Of course adjust this access.admin: settings to whatever you need, but NEVER set this in the default_access_levels: setting for the plugin, or every user will have admin access. You want to maintain control over who can access and who can't, especially those logging in with OAuth2 providers as there is no control over 'who' can sign in.

Troubleshooting

To get a quick state of your OAuth2 configuration, you can simply dump out the Grav user on a temporary secure page:

---
title: OAuth2 Test
cache_enabled: false
process:
    twig: true
access:
    site.login: true
---

# Grav User

{{ vardump(grav.user) }}