authentication-header-provider.md

Authentication header providers

Motivation

Most of the time, microservices will need an authentication header. In that way, they will know who is doing the request and to authorize it to interact with a resource or not.

Even if authentication headers are part of the request headers, we don't want to specify them each time we call the request method. Therefore, we can use authentication header providers to inject authentication headers in requests and decouple them from the regular headers.

Description

Create your own Provider that should implement AuthenticationHeaderProviderInterface and should be tagged api_platform_ms.authentication_header_provider.

If you are using autoconfiguration, the tag will automatically be applied.

Behind the scene, for each request, the HTTP Client will iterate over providers and call AuthenticationHeaderProviderInterface::supports in order to retrieve the good provider. The first provider that will have its supports method returning true will be used.

You can refer to the Symfony documentation to know more about Service Tags (autoconfiguration, priority...)

Here is an example

services:
    # You can benefit of autoconfiguration
    _defaults:
        autoconfigure: true

    # Or you can apply the tag yourself
    App\Autentication\BearerAuthenticationHeaderProvider:
        tags:
            - { name: 'api_platform_ms.authentication_header_provider', priority: 10 }

namespace App\Authentication;

use App\User\Security\OAuthAccessTokenInterface;
use Mtarld\ApiPlatformMsBundle\HttpClient\AuthenticationHeaderProviderInterface;

class BearerAuthenticationHeaderProvider implements AuthenticationHeaderProviderInterface
{
    private $accessToken;

    public function __construct(OAuthAccessTokenInterface $accessToken)
    {
        $this->accessToken = $accessToken;
    }

    public function getHeader(): string
    {
        return 'Authorization';
    }

    public function getValue(): string
    {
        return sprintf('Bearer %s', $this->accessToken->getOAuthAccessToken());
    }

    public function supports(array $context): bool
    {
        // $context is an hashmap containing 'method', 'uri', 'options' and 'microservice'.
        return null !== $this->accessToken->getOAuthAccessToken() && 'product' === $context['microservice']->getName();
    }

    public static function getDefaultPriority(): int
    {
        return 10;
    }
}