Fastify and token authentication

We will generate a new fastify project via the fastify-cli.

fastify generate fastify-api-auth

The plugin we will use for this is @fastify/bearer-auth. You can install it like so.

npm i @fastify/bearer-auth

Lets create a new route. Inside the routes directory create a new folder named auth and add a new index.js file to it. Here is the code for the new route.

module.exports = async function (fastify, opts) {
  fastify.get('/', async function (request, reply) {
    reply.send('Hello world')
  })
}

Inside the plugins directory lets create a new file and call it auth.js and include the code below.

const fp = require('fastify-plugin')

// Here we have out super secret keys.
const keys = new Set(['a-super-secret-key', 'another-super-secret-key'])

module.exports = fp(async function (fastify, opts) {
    fastify.register(require('@fastify/bearer-auth'), { keys })
})

On line 6 we have our super secret keys hard coded. This is just for testing. They should be coming from an environment variable or a secrets management solution like AWS secrets manager.

Now, lets run our app and give it a test.

npm run dev

Lets run a curl command on our terminal.

curl --location --request GET 'localhost:3000/auth' \
--header 'Authorization: Bearer a-super-secret-key'

You should see the text Hello World. If you pass in a bad key you should see {"error":"invalid authorization header"}.