else
    TF_SetStatus(status, TF_OK, "");
}

static int64_t Tell(const TF_WritableFile* file, TF_Status* status) {
  auto posix_file = static_cast<PosixFile*>(file->plugin_file);

  // POSIX's `ftell` returns `long`, do a manual cast.
  int64_t position = int64_t{ftell(posix_file->handle)};
  if (position < 0)
    TF_SetStatusFromIOError(status, errno, posix_file->filename);
  else

!!! info
    If you are using containers, for example with Docker or Kubernetes, I'll tell you more about that in the next chapter: [FastAPI in Containers - Docker](docker.md){.internal-link target=_blank}.

    In particular, when running on **Kubernetes** you will probably **not** want to use Gunicorn and instead run **a single Uvicorn process per container**, but I'll tell you about it later in that chapter.

## Gunicorn with Uvicorn Workers

# This manifest installs the Istio install-cni container, as well
# as the Istio CNI plugin and config on
# each master and worker node in a Kubernetes cluster.
{{- $defaultBinDir :=
    (.Capabilities.KubeVersion.GitVersion | contains "-gke") | ternary
      "/home/kubernetes/bin"
      "/opt/cni/bin"
}}
kind: DaemonSet
apiVersion: apps/v1
metadata:
  name: istio-cni-node
  namespace: {{ .Release.Namespace }}
  labels:

└── requirements.txt
```

#### Behind a TLS Termination Proxy

If you are running your container behind a TLS Termination Proxy (load balancer) like Nginx or Traefik, add the option `--proxy-headers`, this will tell Uvicorn to trust the headers sent by that proxy telling it that the application is running behind HTTPS, etc.

```Dockerfile
CMD ["uvicorn", "app.main:app", "--proxy-headers", "--host", "0.0.0.0", "--port", "80"]
```

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.

// letter. At least 2 characters long.
var validSiteNameRegex = regexp.MustCompile("^[a-z][a-z0-9-]+$")

// LookupSite - get site related configuration. Loads configuration from legacy
// region sub-system as well.
func LookupSite(siteKV KVS, regionKV KVS) (s Site, err error) {
	if err = CheckValidKeys(SiteSubSys, siteKV, DefaultSiteKVS); err != nil {
		return
	}
	region := env.Get(EnvRegion, "")
	if region == "" {

  - type: textarea
    id: current-behavior
    attributes:
      label: Current Behavior
      description: Tell us what happens
    validations:
      required: true
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:

  - type: textarea
    id: current-behavior
    attributes:
      label: Current Behavior
      description: Tell us what happens
    validations:
      required: true
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:

## Configuration protocol

Ztunnel, of course, needs to be dynamically configured in order to make decisions on how it should handle traffic.
For this purpose, we chose to use xDS transport protocol due to our expertise and existing infrastructure, and because the protocol is well suited to our needs.

- **Cross-Language Compatibility:** Java serialization is inherently Java-centric and does not support cross-language scenarios well.

- **Type Safety:** Java serialization does not enforce type safety as strictly as some alternatives, potentially leading to runtime errors.

## Decision