Logging users in via Express / Auth0 back-end - node.js

Question

Auth0 documentation describes how to set up express-jwt middleware to protect endpoints. The trouble is that the documentation doesn't seem to cover how you get a valid JWT in the first place.
On the angular side, there's documentation on using angular plugins to implement a login page, that's fine. How would one implement a route using express that would take a username/password and return to the client the appropriate JWT such that subsequent requests would be authorized?
I think I may be missing a basic concept about JWT here; via Auth0, when using Username-Password-Authentication, my guess is that Auth0 acts as the repo for those credentials. There's documentation out there about wiring passport to auth0 and JWT, the problem with those is that this documentation assumes that the username/password database is some MongoDB instance locally...I want to avoid that type of setup which was an initial attraction with auth0.
Are there sample projects that cover this, showing how to get a valid JWT on a back-end, without some separate front-end angular app requesting it first?

Answer 1

I use passport.js built in local strategy for authentication and store user information in a JWT that I read on routes that require authorization.
User id's can be serialized/deserialized into and out of the express sessionto obtain the user identifier using the auth token (JWT) in the request. This is in my opinion the best approach since it limits the amount of data stored on the client and provides better security than storing any user information. Here's an example of this in express:
//Set a session secret
var secrets = { sessionSecret: process.env.secret || 'my secret string'};
//Require express-jwt and set a secret for the cookie
var expressJwt = require('express-jwt');
var validateJwt = expressJwt({ secret: secrets.sessionSecret });
//Returns a jwt token signed by the app secret
var signToken = function(id) {
return jwt.sign({
id: id
}, secrets.sessionSecret, {
expiresInMinutes: 60 * 24 // 24 hours
});
};
//Set token cookie directly
var setTokenCookie = function(req, res) {
if (!req.user) {
return res.status(404).json({
message: 'Error during user validation'
});
}
var token = signToken(req.user.id, req.user.role);
res.cookie('token', JSON.stringify(token));
};
//Check to see if user is authenticated (call this when a route is requested)
var isAuthenticated = function(req, res, next) {
// allow access_token to be passed through query parameter as well
if (req.body && req.body.hasOwnProperty('access_token')) {
req.headers.authorization = 'Bearer ' + req.body.access_token;
}
// Validate jwt token
return validateJwt(req, res, next);
};
You can use these methods as middleware in express. Say the above code was token.js, you can force it to execute on each request to a route like this:
app.get('/employee', token.isAuthenticated, employeeController.getEmployees);
I haven't worked with angular but it works great on the backbone projects i've worked on and this process should work with any browser based client that can supply a X-auth cookie on each request. You can do this by using the ajax setup:
$(document).ajaxSend(function(event, request) {
var token = readCookie('token');
if (token) {
request.setRequestHeader('authorization', 'Bearer ' + token);
}
});
Here is an example of middleware that validates a users login and returns a token to the client that can be used on subsequent requests:
var validateLogin = function (req, res, next) {
var username = req.params.username;
// Authenticate using local strategy
passport.authenticate('local', function(err, user, info) {
if (err) {
return next(err);
}
if (!user) {
return res.status(404).json({
info: [{
msg: info.message
}]
});
}
// Send user and authentication token
var token = token.signToken(user.id, user.role);
res.cookie('token', token);
res.render('index', {token: token, user: user});
})(req, res, next);
};

Answer 2

#FrobberOfBits
This is to answer the follow-up Q posted by FrobberOfBits on Feb 6, 2016 at 3:04
I use auth0 for local + social media authentication.
The way auth0 works is, you hand over the approach to authenticate to auth0 ...either it be local with db or social media.
It is a bundled approach where local db and social media authentication is all bundled and provided as a service to you by auth0.
Hope this helps.