Dear community. First of all I want to express my appriciation for the developers of Symfony. I'm using it for many years and helps me to develop new features pretty quick.

Current Scenario

Currently I have a multi-tenant (SaaS) REST API. Each tenant has its own database, but they all have the exact same schema. For each tenant I have an .env file (e.g. .env.tenant1.local, .env.tenant.env). Each tenant has it own domainname and, so also a VHost within Apache. Within that VHost I override the APP_ENV so that each domain read the correct env file. I have a shell script that iterates over all the tenants to execute the Doctrine migrations (e.g. APP_ENV=tenant1 php bin/console doctrine:migrations:migrate)

The Problem

I have to request SSL certificates for each domain. Also using the Symfony Messenger component, with for example RabbitMQ, means I have to run a process for each tenant. With five tenants that is okay, but the amount of tenants is growing each year. So I'm thinking of moving to one domain for the API and determine the tenant based on a header, e.g. X-Tenant-ID. However that means I need to switch the database connection on runtime and that is where I got stuck. I know I can configure more connections in the configuration of Doctrine, but that means a redeploy for each new tenant, which I don't want.

What I've Tried

I have tried multiple solutions myself (compiler passes and stuff) which worked half. Recently I used ChatGPT Codex and it gave a working solution, but I want to confirm if this is the Symfony way. What it basically did was:

• It created a new Application class for the console, and added a required input, the tenant ID. Within bin/console it uses this new Application.

final class Application extends BaseApplication
{
    public function __construct(KernelInterface $kernel)
    {
        parent::__construct($kernel);

        $this->getDefinition()->addOption(new InputOption(
            'tenant',
            null,
            InputOption::VALUE_REQUIRED,
            'Tenant ID for tenant-aware database access.'
        ));
    }
}

• Created two subscribers that catches kernel.request and console.command, reads the header of input and stores it within a TenantContext service.

• It created a TenantDriverMiddleware that implements the Doctrine\DBAL\Driver\Middleware interface from Doctrine. Within the wrap method it reads the tenant from the context, gets the database url from a config file and calls the parent::connect with the updated params.

#[AsMiddleware(connections: ['default'], priority: 100)]
final readonly class TenantDriverMiddleware implements Middleware
{
    private DsnParser $dsnParser;

    public function __construct(private TenantContext $tenantContext)
    {
        $this->dsnParser = new DsnParser();
    }

    public function wrap(Driver $driver): Driver
    {
        $tenantContext = $this->tenantContext;
        $dsnParser = $this->dsnParser;

        return new class ($driver, $tenantContext, $dsnParser) extends AbstractDriverMiddleware {
            public function __construct(
                Driver $driver,
                private readonly TenantContext $tenantContext,
                private readonly DsnParser $dsnParser,
            ) {
                parent::__construct($driver);
            }

            public function connect(
                #[SensitiveParameter]
                array $params,
            ): DriverConnection {
                $tenantConfig = $this->tenantContext->getTenantConfigOrDefault();
                $resolved = $this->dsnParser->parse($tenantConfig->databaseUrl);
                $resolvedParams = array_merge($params, $resolved);

                if (isset($params['dbname_suffix'], $resolvedParams['dbname'])) {
                    $resolvedParams['dbname'] .= $params['dbname_suffix'];
                }

                unset($resolvedParams['url']);

                return parent::connect($resolvedParams);
            }
        };
    }
}

• It also created some middleware for the Messenger component and created a TenantStamp.
• There is a default database connection in the .env file, because Symfony needs it.

It works perfectly. My endpoints work with the X-Tenant-ID header, and I can run migations and other commands by running php bin/console doctrine:migrations:migrate --tenant=tenant1. It also works with the VichUploaderBundle which I have installed.

The Question

Is the solution Codex created good practice? Will I run into caching or connection issues on production? Or are there other ways of solving this problem? I know I could just put everything in one database and add a tenant_id column to my tables, but that is not an option. I'm really hoping that there is a good way in Symfony to fix this problem.

Best regards,
Jan Doornbos from The Netherlands