Getting "error": "Unknown authentication strategy \"jwt\"" - express

Question

I'm implementing an authorization feature using Express, Mongoose, Passport and JWT.
I'm able to register a user ok. I'm able to authenticate and generate a JWT, which I can parse on the JWT site, but for some reason, I'm getting an Unknown authentication strategy error message.
I have all my code blocks laid out on a Plunker instance at:
https://plnkr.co/edit/ZNjQwcZ4rMymzBXNy5nX?p=catalogue
Here is my passport.js file, which contains my strategy:
var JwtStrategy = require('passport-jwt').Strategy;
// load up the user model
var User = require('../models/user');
var config = require('../config/database'); // get db config file
module.exports = function(passport) {
var opts = {};
opts.secretOrKey = config.secret;
passport.use(new JwtStrategy(opts, function(jwt_payload, done) {
User.findOne({id: jwt_payload.id}, function(err, user) {
if (err) {
return done(err, false);
}
if (user) {
done(null, user);
} else {
done(null, false);
}
});
}));
};
Here is what my authentication.js file looks like:
var express = require('express');
var router = express.Router();
var jwt = require('jwt-simple');
var config = require('../config/database');
var User = require('../models/user');
router.route('/')
.post(function(req, res) {
User.findOne({
name: req.body.name
}, function(err, user) {
if (err)
res.send(err);
if (!user) {
res.send({success: false, msg: 'Authentication failed. User not found.'});
} else {
// check if password matches
user.comparePassword(req.body.password, function (err, isMatch) {
if (isMatch && !err) {
// if user is found and password is right create a token
var token = jwt.encode(user, config.secret);
// return the information including token as JSON
res.json({success: true, token: 'JWT ' + token});
} else {
res.send({success: false, msg: 'Authentication failed. Wrong password.'});
}
});
}
});
});
module.exports = router;
Here is the endpoint I'm calling that is generating the error:
var express = require('express');
var router = express.Router();
var jwt = require('jwt-simple');
var config = require('../config/database');
var passport = require('passport');
var User = require('../models/user');
router.route('/')
.get(passport.authenticate('jwt', { session: false}), function(req, res) {
var token = getToken(req.headers);
if (token) {
var decoded = jwt.decode(token, config.secret);
User.findOne({
name: decoded.name
}, function(err, user) {
if (err) throw err;
if (!user) {
return res.status(403).send({success: false, msg: 'Authentication failed. User not found.'});
} else {
res.json({success: true, msg: 'Welcome in the member area ' + user.name + '!'});
}
});
} else {
return res.status(403).send({success: false, msg: 'No token provided.'});
}
});
getToken = function (headers) {
if (headers && headers.authorization) {
var parted = headers.authorization.split(' ');
if (parted.length === 2) {
return parted[1];
} else {
return null;
}
} else {
return null;
}
};
module.exports = router;

Answer 1

You forgot to include your own passport.js module in the application. This leads nodejs to not find the definition of JWTStrategy which is ultimately causing the error that you see.
In your endpoint file, just include the local passport.js file:
var express = require('express');
var router = express.Router();
var jwt = require('jwt-simple');
var config = require('../config/database');
var passport = require('passport');
require('./passport')(passport) // as strategy in ./passport.js needs passport object
var User = require('../models/user');
router.route('/')
.get(passport.authenticate('jwt', { session: false}), function(req, res) {
var token = getToken(req.headers);
...

Answer 2

if you look at your passport configuration file (passport.js) you will see
module.exports = function (passport) {
//bla bla bla
}
as you see it needs passport instance
now how to pass this instance to your passport.js file
simply
var passport = require('passport');// create a passport instance
var myPassportService = require('../config/passport')(passport);// pass it into passport.js file
hope this helps you

Answer 3

Just on the off chance that someone is having the same issue but it isn't resolved by the top answer.
My issue ended up being accidently moving node modules into another directory and then of course running npm install to fix module import errors. I ended up with two node_modules directory and although the server started fine, passport errored when it was called.
I eventually found the blunder and removed the second node_modules directory and the Unknown authentication strategy “jwt” was no resolved.