Plugins: Booting Up

Sometimes your Plugin might need to do something one time during the Plugin loading process. This is where the BootablePlugin interface comes into play. Implementing this interface ensures that your Plugin has an opportunity to complete its task after all other Plugin loading procedures have finished.

On the surface implementing the EventAwarePlugin and listening to the Engine::START_UP_EVENT is the same as implementing BootablePlugin. A slight difference is that the Plugin loading process happens before the Engine::START_UP_EVENT is emitted. The impact this has on your running application is that the BootablePlugin will execute its boot method as soon as the individual Plugin is done loading. The EventAwarePlugin listening to Engine::START_UP_EVENT will only execute after all Plugins have finished loading. There's also simply less boilerplate with the BootablePlugin.

Implementing BootablePlugin

Continuing our theme of logging stuff in examples we'll log out a message when our Plugin is booted. It is important to note that the boot method is the very last thing that is executed during Plugin loading.


namespace Acme;

use Amp\Promise;
use Cspray\Labrador\Plugin\BootablePlugin;
use Psr\Log\LoggerInterface;
use function Amp\call;

class BootLoggingPlugin implements BootablePlugin {

    private $logger;

    public function __construct(LoggerInterface $logger) {
        $this->logger = $logger;

    public function boot() : Promise {
        return call(function() {
            $this->logger->info('Our Plugin has finished booting!'); 


Next Steps

If you find yourself writing a Plugin that requires services another Plugin provides you may want to take a look at Plugins: Depending On Other Plugins.