Rules for Custom JWT Claims

Custom claims inside the JWT are used to tell Hasura about the role of the caller, so that Hasura may enforce the necessary authorization rules to decide what the caller can and cannot do. In the Auth0 dashboard, navigate to Rules.

Click on the + Create Rule button. In the next screen, select the Empty rule template.

Name the rule as hasura-jwt-claims.

Add the following script to the rule.

function (user, context, callback) {
  const namespace = "https://hasura.io/jwt/claims";
  context.accessToken[namespace] =
    {
      'x-hasura-default-role': 'user',
      // do some custom logic to decide allowed roles
      'x-hasura-allowed-roles': ['user'],
      'x-hasura-user-id': user.user_id
    };
  callback(null, user, context);
}