## Migrations

Because we are using SQLAlchemy directly and we don't require any kind of plug-in for it to work with **FastAPI**, we could integrate database <abbr title="Automatically updating the database to have any new column we define in our models.">migrations</abbr> with <a href="https://alembic.sqlalchemy.org" class="external-link" target="_blank">Alembic</a> directly.

If in your use case there's no problem in running those previous steps **multiple times in parallel** (for example if you are not running database migrations, but just checking if the database is ready yet), then you could also just put them in each container right before starting the main process.

### Single Container

* Modèles **SQLAlchemy** (indépendants des extensions Flask, afin qu'ils puissent être utilisés directement avec des *workers* Celery).
* Modèle de démarrages basiques pour les utilisateurs (à modifier et supprimer au besoin).
* Migrations **Alembic**.
* **CORS** (partage des ressources entre origines multiples, ou *Cross Origin Resource Sharing*).
* *Worker* **Celery** pouvant importer et utiliser les modèles et le code du reste du backend.

## Create the tables

In this case, we are creating the tables in the same Python file, but in production, you would probably want to create them with Alembic, integrated with migrations, etc.

Here, this section would run directly, right before starting your **FastAPI** application.

* Create an `engine`.
* Create all the tables from the `metadata` object.

```Python hl_lines="25-28"

And it will work and will be useful **during development**.

But if your connection to the server is lost, the **running process** will probably die.

And if the server is restarted (for example after updates, or migrations from the cloud provider) you probably **won't notice it**. And because of that, you won't even know that you have to restart the process manually. So, your API will just stay dead. 😱

### Run Automatically on Startup