Rewrite cookie paths when using grunt-connect-proxy - cookies

Question

During development I use grunt-connect-proxy to make some remote APIs locally available. This works just fine, except that the rewrite rules that I use are not applied to cookies:
proxies: [{
context: '/publicPath',
host: 'localhost',
port: 8080,
rewrite: {
'^/publicPath': '/privatePath'
}
}]
If the remote API sets a cookie with path /privatePath it must be rewritten to /publicPath.
E.g. When using Apache httpd I'd use the ProxyPassReverseCookiePath-Directive. How do I do it with grunt-connect-proxy?

Answer 1

Thanks to this answer in "Rewrite response headers with node-http-proxy" I managed to figure it out. I created the following middleware:
function rewriteSetCookie(req, res, next) {
var isProxyRequest = req.url.lastIndexOf('/publicPath', 0) === 0;
if (isProxyRequest) {
// we intercept the writeHead function, so that we can exchange headers just before they are written
var oldWriteHead = res.writeHead;
res.writeHead = function () {
var cookie = res.getHeader('Set-Cookie');
if (cookie) {
res.setHeader('Set-Cookie', cookie.map(function(item) {
// Replace paths in all cookies. The simple string/replace approach might be too naive in some cases, so check before you copy&paste before thinking
return item.replace(/\/privatePath/, '/publicPath');
}));
}
oldWriteHead.apply(res, arguments);
};
}
next();
}
Just for reference here is the full configuration so that you can see how to use the middleware:
connect: {
server: {
options: {
hostname: 'localhost',
base: 'myBaseDir',
open: true,
middleware: function (connect, options) {
if (!Array.isArray(options.base)) {
options.base = [options.base];
}
// Setup the proxy
var middlewares = [rewriteSetCookie, proxySnippet];
// ^^^^^^^^^^^^^^^^- Here is is used!
// Serve static files.
options.base.forEach(function(base) {
middlewares.push(connect.static(base));
});
// Make directory browse-able.
var directory = options.directory || options.base[options.base.length - 1];
middlewares.push(connect.directory(directory));
return middlewares;
}
},
proxies: [{
context: '/publicPath',
host: 'localhost',
port: 8080,
rewrite: {
'^/publicPath': '/privatePath'
}
}]
}
}