A Cors middleware is a function that receives the request origin from the gateway and must return a boolean value (or a Promise) to inform if the given origin is allowed.

Each filter must be defined on its own .js file.

Example:

/**
 * @param origin the origin extracted from request.
 */
module.exports = function (origin) {
    return (whitelist.indexOf(origin) !== -1);
};

or, using Promises:

module.exports = function (origin) {
    return new Promise((resolve, reject) => {
        setTimeout(function(){resolve(whitelist.indexOf(origin) !== -1);}, 10);
    });
};

You can configure a cors middleware through:

• Admin Rest API: POST /cors
• SDK: sdk.middleware.addCors(name, fileName);
• CLI: treeGatewayConfig middleware cors -a <name> ./filename.js