iptables -t nat -N ISTIO_POSTRT
iptables -t nat -A POSTROUTING -j ISTIO_POSTRT

iptables -t nat -N ISTIO_POSTRT
iptables -t nat -A POSTROUTING -j ISTIO_POSTRT
iptables -t nat -A ISTIO_POSTRT -m owner --socket-exists -p tcp -m set --match-set istio-inpod-probes-v4 dst -j SNAT --to-source 169.254.7.127
ip6tables -t nat -N ISTIO_POSTRT
ip6tables -t nat -A POSTROUTING -j ISTIO_POSTRT

    - istio-proxy container exists and
        - does not have DISABLE_ENVOY environment variable (which triggers proxyless mode)
        - has a istio-proxy container, with first 2 args "proxy" and "sidecar" - or less then 2 args, or first arg not proxy.
        - "sidecar.istio.io/inject" is not false
        - "sidecar.istio.io/status" exists

### Redirect API

---

Pour revenir à l'exemple de code précédent, **FastAPI** permet de :

* Valider que `item_id` existe dans le chemin des requêtes `GET` et `PUT`.
* Valider que `item_id` est de type `int` pour les requêtes `GET` et `PUT`.
    * Si ce n'est pas le cas, le client voit une erreur utile et claire.
* Vérifier qu'il existe un paramètre de requête facultatif nommé `q` (comme dans `http://127.0.0.1:8000/items/foo?q=somequery`) pour les requêtes `GET`.

```console
// Create an env var MY_NAME in line for this program call
$ MY_NAME="Wade Wilson" python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python

// The env var no longer exists afterwards
$ python main.py

Hello World from Python
```

</div>

!!! tip

    * ReDoc.

---

Voltando ao código do exemplo anterior, **FastAPI** irá:

* Validar que existe um `item_id` na rota para requisições `GET` e `PUT`.
* Validar que `item_id` é do tipo `int` para requisições `GET` e `PUT`.
    * Se não é validado, o cliente verá um útil, claro erro.
* Verificar se existe um parâmetro de _query_ opcional nomeado como `q` (como em `http://127.0.0.1:8000/items/foo?q=somequery`) para requisições `GET`.

*   `tf.cond` emits a StatelessIf op if the branch functions are stateless and
    do not touch any resources.
*   `tf.cond`, `tf.while` and `if` and `while` in AutoGraph now accept a
    nonscalar predicate if has a single element. This does not affect non-V2
    control flow.
*   `tf.while_loop` emits a StatelessWhile op if the cond and body functions are

When the **container** is started and running (started from a **container image**) it could create or change files, environment variables, etc. Those changes will exist only in that container, but would not persist in the underlying container image (would not be saved to disk).

A container image is comparable to the **program** file and contents, e.g. `python` and some file `main.py`.

    * ReDoc.

---

Volviendo al ejemplo de código anterior, **FastAPI** va a:

* Validar que existe un `item_id` en el path para requests usando `GET` y `PUT`.
* Validar que el `item_id` es del tipo `int` para requests de tipo `GET` y `PUT`.
    * Si no lo es, el cliente verá un mensaje de error útil y claro.

I'll tell you a bit more about these **concepts** here, and that would hopefully give you the **intuition** you would need to decide how to deploy your API in very different environments, possibly even in **future** ones that don't exist yet.

By considering these concepts, you will be able to **evaluate and design** the best way to deploy **your own APIs**.

In the next chapters, I'll give you more **concrete recipes** to deploy FastAPI applications.