This module lets you authenticate HTTP requests using JSON Web Tokens in your Koa (node.js) applications.
See this article for a good introduction.
- If you are using
koa
version 2+, and you have a version of node < 7.6, installkoa-jwt@2
. koa-jwt
version 3+ on the master branch usesasync
/await
and hence requires node >= 7.6.- If you are using
koa
version 1, you need to installkoa-jwt@1
from npm. This is the code on the koa-v1 branch.
$ npm install koa-jwt
The JWT authentication middleware authenticates callers using a JWT
token. If the token is valid, ctx.state.user
(by default) will be set
with the JSON object decoded to be used by later middleware for
authorization and access control.
The token is normally provided in a HTTP header (Authorization
), but it
can also be provided in a cookie by setting the opts.cookie
option
to the name of the cookie that contains the token. Custom token retrieval
can also be done through the opts.getToken
option. The provided function
should match the following interface:
/**
* Your custom token resolver
* @this The ctx object passed to the middleware
*
* @param {object} opts The middleware's options
* @return {String|null} The resolved token or null if not found
*/
The resolution order for the token is the following. The first non-empty token resolved will be the one that is verified.
opts.getToken
function- check the cookies (if
opts.cookie
is set) - check the Authorization header for a bearer token
Normally you provide a single shared secret in opts.secret
, but another
alternative is to have an earlier middleware set ctx.state.secret
,
typically per request. If this property exists, it will be used instead
of the one in opts.secret
.
You can provide a async function to jwt for it check the token is revoked.
Only you set the function in opts.isRevoked
. The provided function should
match the following interface:
/**
* Your custom isRevoked resolver
*
* @param {object} ctx The ctx object passed to the middleware
* @param {object} decodedToken Content of the token
* @param {object} token token The token
* @return {Promise} If the token is not revoked, the promise must resolve with false, otherwise (the promise resolve with true or error) the token is revoked
*/
var Koa = require('koa');
var jwt = require('koa-jwt');
var app = new Koa();
// Custom 401 handling if you don't want to expose koa-jwt errors to users
app.use(function(ctx, next){
return next().catch((err) => {
if (401 == err.status) {
ctx.status = 401;
ctx.body = 'Protected resource, use Authorization header to get access\n';
} else {
throw err;
}
});
});
// Unprotected middleware
app.use(function(ctx, next){
if (ctx.url.match(/^\/public/)) {
ctx.body = 'unprotected\n';
} else {
return next();
}
});
// Middleware below this line is only reached if JWT token is valid
app.use(jwt({ secret: 'shared-secret' }));
// Protected middleware
app.use(function(ctx){
if (ctx.url.match(/^\/api/)) {
ctx.body = 'protected\n';
}
});
app.listen(3000);
Alternatively you can conditionally run the jwt
middleware under certain conditions:
var koa = require('koa');
var jwt = require('koa-jwt');
var app = new Koa();
// Middleware below this line is only reached if JWT token is valid
// unless the URL starts with '/public'
app.use(jwt({ secret: 'shared-secret' }).unless({ path: [/^\/public/] }));
// Unprotected middleware
app.use(function(ctx, next){
if (ctx.url.match(/^\/public/)) {
ctx.body = 'unprotected\n';
} else {
return next();
}
});
// Protected middleware
app.use(function(ctx){
if (ctx.url.match(/^\/api/)) {
ctx.body = 'protected\n';
}
});
app.listen(3000);
For more information on unless
exceptions, check koa-unless.
You can also add the passthrough
option to always yield next,
even if no valid Authorization header was found:
app.use(jwt({ secret: 'shared-secret', passthrough: true }));
This lets downstream middleware make decisions based on whether ctx.state.user
is set.
If you prefer to use another ctx key for the decoded data, just pass in key
, like so:
app.use(jwt({ secret: 'shared-secret', key: 'jwtdata' }));
This makes the decoded data available as ctx.state.jwtdata
.
You can specify audience and/or issuer as well:
app.use(jwt({ secret: 'shared-secret',
audience: 'http://myapi/protected',
issuer: 'http://issuer' }));
If the JWT has an expiration (exp
), it will be checked.
If the tokenKey
option is present, and a valid token is found, the original raw token
is made available to subsequent middleware as ctx.state[opts.tokenKey]
.
This module also support tokens signed with public/private key pairs. Instead of a secret, you can specify a Buffer with the public key:
var publicKey = fs.readFileSync('/path/to/public.pub');
app.use(jwt({ secret: publicKey }));
If the secret
option is a function, this function is called for each JWT received in
order to determine which secret is used to verify the JWT.
The signature of this function should be (header) => [Promise(secret)]
, where
header
is token header. For instance to support JWKS token header should contain
alg
and kid
: algorithm and key id fields respectively.
This option can be used to support JWKS (JSON Web Key Set) providers by using node-jwks-rsa. For example:
const { koaJwtSecret } = require('jwks-rsa');
app.use(jwt({ secret: koaJwtSecret({
jwksUri: 'https://sandrino.auth0.com/.well-known/jwks.json',
cache: true,
cacheMaxEntries: 5,
cacheMaxAge: ms('10h') }),
audience: 'http://myapi/protected',
issuer: 'http://issuer' }));
- jsonwebtoken — JSON Web Token signing and verification
Note that koa-jwt no longer exports the sign
, verify
and decode
functions from jsonwebtoken
in the koa-v2 branch.
$ npm install
$ npm test
Stian Grytøyr
This code is largely based on express-jwt.