polling.go

	ticker := time.NewTicker(time.Minute)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			// poll the image build status
		case evt := <-webhookRequest:
			ticker.Reset(time.Minute)
			// update the image build status with evt
		case <-time.After(30*time.Minute):
			// fail on overall timeout
		}
		// break if image build status != pending
	}