The `DISCOURSE_FULL_SCREEN_LOGIN` option allows the SSO login page to be presented within the main browser window, rather than a popup. If SAML is your only authentication method this can look neater, as when the user clicks the Log In button the login page will follow through within the main browser window rather than opening a pop-up. This setting is commented out by default - if you want full screen login uncomment that line and set the value to true (as per the example above).
For non docker:
Add the following settings to your `discourse.conf` file: