koa-police-jwt

A koa-police strategy to login users with JSON Web Token.

Installation

Simply run

$ npm install --save koa-police-jwt

Usage

This module exports a function that take a the JWT secret and returns a koa-police strategy. You can call it like this.

var koaPoliceJwt = require('koa-police-jwt');
var jwtStrategy = koaPoliceJwt({secret: 'my-secret'});

You then only need to add this strategy to the defaultStrategies array when initializing koa-police. A full example is provided in the example directory.

Customization

Getting the token

By default, koa-police-jwt will look for the Authorization header with the form Bearer [token]. However, you can customize the way you want to look for the token. If you want to use another header, you can pass header: 'x-my-header' in the initialization options. This will use x-my-header instead of authorization. If you want to use a query parameter, you can pass query: 'myQueryParam', this will look in the query parameters for the token. Both options can be used together.

If you need more flexibility to get the token, you can pass a function to getToken, which will be passed the request as parameter, for example.

var jwtStrategy = koaPoliceJwt({
  secret: 'my-secret',
  getToken: function (request) {
    return request.body.myToken;
  }});

Using a dynamic secret

If you need to use a dynamic secret, you can pass a generator function instead of a string.

var jwtStrategy = koaPoliceJwt({
  secret: function *(context) {
    var mySecret = yield getMySecretFromWhereverIWant(context);
    return mySecret;
  }
});

Post processing decoded data

If you want to process the decoded data, you can pass a generator function to the processDecoded option. For example:

var jwtStrategy = koaPoliceJwt({
  secret: 'my-secret',
  processDecoded: function *(context, decoded) {
    return yield context.db.findUser(decoded.userId);
  }
});

The returned result will be replace by whatever you return in this function.

Limiting allowed scopes

By default, the jwtStrategy will not care which scope you are using, however, you can restrict the scopes you want to use by passing an array to the allowedScopes option.

var jwtStrategy = koaPoliceJwt({
  secret: 'my-secret',
  allowedScopes: ['user']
});

So if you have koa-police initialized in the following way

app.use(koaPolice({
  defaultStrategies: [jwtStrategy],
  policies: [{path: /\/admin.*/, scope: 'admin'}, {path: /.*/, scope: 'user'}]
}));

jwtStrategy will always fail for the admin scope.