Using Laravel 5.8 authentication with external JSON API (Creating own ServiceProvider)

Hi,

I'm building a Laravel 5.8 application to be the front-end to an external API written in Go. I POST a user/pass to the API which then responds with either HTTP/200 and a JSON Token (JWT) or an HTTP/401 to signal the credentials are invalid.

I would like to use Laravel's built-in auth mechanism (or anything which makes this work really) to be able to create pages and routes only for logged in users. It seems a lot of work to reinvent the wheel.

[TLDR] Basically I need some code which checks if the API returns an HTTP/200, stores the token somewhere (session/cookie [but not database]) and then provide's some way to easily (virtually) log users into the Laravel app. That way I can create pages for logged in users only.

So far I have done this:

APIUser class:

protected $attributes = [];

    public function __construct($attributes)
    {
        $this->attributes = $attributes;
    }
    public function __get($attribute)
    {
        return $this->attributes[$attribute];
    }
    public function getKey()
    {
        return $this->attributes['userId'];
    }
    /**
     * Get the name of the unique identifier for the user.
     *
     * @return string
     */
    public function getAuthIdentifierName()
    {
        return 'userId';
    }
    /**
     * Get the unique identifier for the user.
     *
     * @return mixed
     */
    public function getAuthIdentifier()
    {
        return $this->attributes['userId'];
    }
    /**
     * Get the password for the user.
     *
     * @return string
     */
    public function getAuthPassword()
    {
        return null;
    }

    public function getAuthIdentifierEmail()
    {
        return $this->attributes['email'];
    }

    /**
     * Get the token value for the "remember me" session.
     *
     * @return string
     */
    public function getRememberToken()
    {
        return $this->attributes[$this->getRememberTokenName()];
    }
    /**
     * Set the token value for the "remember me" session.
     *
     * @param  string  $value
     * @return void
     */
    public function setRememberToken($value)
    {
        $this->attributes[$this->getRememberTokenName()] = $value;
    }
    /**
     * Get the column name for the "remember me" token.
     *
     * @return string
     */
    public function getRememberTokenName()
    {
    }

    public function getAttributes()
    {
        return $this->attributes;
    }

ApiUserProvider:

protected $model;
    protected $modelUser;

    public function __construct(Request $request)
    {
        $this->model = APIUser::class;
    }

    public function fetchUser($credentials) {
        if ($credentials['email'] and $credentials['password']) {
            $email = $credentials['email'];
            $password = $credentials['password'];

            $client = new \GuzzleHttp\Client([
                'headers' => ['Content-Type' => 'application/json'],
            ]);

            $url = config('apilist.login');

            try {
                $response = $client->request('POST', $url, [
                    'json' => [
                        'email' => $email,
                        'password' => sha1($password),
                    ],
                ]);
            } catch (GuzzleException $e) {
                print_r($e->getResponse());
            }

            $array = json_decode($response->getBody()->getContents(), true);


            if($array["responseMessage"]["code"] == 200){

                $userInfo = $array["responseMessage"]["object"];

                return new $this->model($userInfo);

            } else {
                return $array["responseMessage"]["message"] ?: "Something went wrong. Please try again";
            }
        }
    }

    public function retrieveById($identifier) {
        return $this->modelUser;
    }

    /**
     * Retrieve a user by their unique identifier and "remember me" token.
     *
     * @param  mixed  $identifier
     * @param  string  $token
     * @return \Illuminate\Contracts\Auth\Authenticatable|null
     */
    public function retrieveByToken($identifier, $token) {}

    /**
     * Update the "remember me" token for the given user in storage.
     *
     * @param  \Illuminate\Contracts\Auth\Authenticatable  $user
     * @param  string  $token
     * @return void
     */
    public function updateRememberToken(Authenticatable $user, $token){}

    /**
     * Retrieve a user by the given credentials.
     *
     * @param  array  $credentials
     * @return \Illuminate\Contracts\Auth\Authenticatable|null
     */
    public function retrieveByCredentials(array $credentials){
        $user = $this->fetchUser($credentials);

        return $user;
    }

    /**
     * Validate a user against the given credentials.
     *
     * @param  \Illuminate\Contracts\Auth\Authenticatable  $user
     * @param  array  $credentials
     * @return bool
     */
    public function validateCredentials(Authenticatable $user, array $credentials){
        //return ($credentials['email'] == $user->getAuthIdentifierEmail());
        return true;
    }

config/auth.php:

'providers' => [
        'users' => [
            'driver' => 'apiuserprovider',
        ],

And in the login function, when I do

dd($this->guard()->user());

it gives me user's information. Everything works fine, however, it does not login a user to the system. What is the problem?