JWT key for mercure - symfony

Question

I try generate JWT key for Mercure settings
I use this manual
https://medium.com/#stefan.poeltl/instant-realtime-notifications-with-symfony-and-mercure-e45270f7c8a5
for pass myJWTKey JWT is
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InN1YnNjcmliZSI6W10sInB1Ymxpc2giOlsiKiJdfX0.iTVjHoLv9bB-O5RNnTtzOFxIW-YECk2JXZeMekZ4GwA
I found a token builder ( Signed JSON Web Token )
http://jwtbuilder.jamiekurtz.com/
but I find no setting that generates a correct JWT. How do I do it? What I miss?
I tried generate token for env settings
MERCURE_PUBLISH_URL=http://mercure.dev:3000/.well-known/mercure
# The default token is signed with the secret key: !ChangeMe!
MERCURE_JWT_TOKEN=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InN1YnNjcmliZSI6W10sInB1Ymxpc2giOlsiKiJdfX0.iTVjHoLv9bB-O5RNnTtzOFxIW-YECk2JXZeMekZ4GwA
###< symfony/mercure-bundle ###
This token is for default password in docker-compose
mercure:
image: dunglas/mercure
environment:
# You should definitely change all these values in production
- JWT_KEY=myJWTKey
- DEMO=1
- ALLOW_ANONYMOUS=1
- HEARTBEAT_INTERVAL=30s
- ADDR=:3000
if I change myJWTKey to mysecure pass - how I can generate token?

Answer 1

Just an addition to a great answer by #Daidon. Mercure bundle uses lcobucci/jwt and registers it's factory as a service.
If you want to generate JWT do the following
Pass the factory as an argument with #mercure.hub.default.jwt.factory (here default is for your hub name)
In your service/controller
public function generateJwt(LcobucciFactory $factory): string
{
return $factory->create(['*']);
}
UPD: even easier way to get a JWT token
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Mercure\Authorization;
public function generateJwt(Request $request, Authorization $authorization): string
{
return $authorization->createCookie($request, ['*'])->getValue();
}

Answer 2

You can use different libraries for doing that, a very simple and fast one would be php-jwt
Then do
composer require firebase/php-jwt
And in the code you can do then:
use \Firebase\JWT\JWT;
$key = "12345678";
$payload = [
'mercure' => [
'publish' => ['*'],
],
];
$jwt = JWT::encode($payload, $key); // holds valid jwt now
The library will automatically inject the headers that you need (default: alg HS256, typ: jwt) and set the payload for you. Then it encodes it to base64 and signs it also.
Go on and set a cookie with this jwt or use it in authorization header now :-)
If you want to use the JWT for subscriber authentication, don't forget to put the subscribe key in the payload.
$payload = [
'mercure' => [
'subscribe' => ['*'], // make this a list of concrete topics, don't use *
],
];
Also for that usecase, you can carry around some data in the cookie, by providing a payload key with an object:
$payload = [
'mercure' => [
'subscribe' => ['*'],
'payload' => [
'userId' => $user->getId()
]
],
];

Answer 3

Apologize for late answer, you can simply generate new jwt token once using the official page https://jwt.io/.