GitHub only allows the configuration a single authorization callback URL for each OAuth application, so you will been to create an OAuth application for each wiki domain - github 
GitHub's OAuth integration only allows us to specify a single callback URL. This means that if you are running a wiki farm with multiple DNS roots, you will need to configure a separate application with GitHub for each wiki domain.
# Register an application with GitHub
- Log into GitHub - Visit the Developer applications tab under OAuth applications in your Personal settings. - Click Register New Application. The new OAuth application configuration screen is displayed:
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- githubusercontent.com
#### Set Application name * Enter a name related to your wiki server. #### Set Homepage URL * Enter the URL of a page that describes your wiki server. #### Set Authorization callback URL * Enter `https://example.wiki/auth/github/callback`, replacing `example.wiki` with your wiki server root domain. Note: If you are not ready to use HTTPS yet, you can use `http://example.wiki/auth/github/callback` Save your settings by clicking **Register application**. The new application's settings are shown:  This screen also allows you to adjust any settings, and add an logo. * Record the `Client ID` and `Client Secret` for use in configuring the wiki server. ### Configure Wiki The wiki is configured by adding the `client ID` and `client secret` to the wiki domain part of the configuration. ```JSON { "farm": true, "security_type": "passportjs", "wikiDomains": { "example.wiki": { "github_clientID": "CLIENT ID", "github_clientSecret": "CLIENT SECRET" } } } ```