```mermaid
graph TD
    subgraph ConfigStore
        xcs(XDS Client)
        ccs(CRD Client)
        fcs(Filesystem Client)
        acs(Aggregate)

the policy propagation from Istiod to Envoy and the final AuthorizationPolicy list merged
from multiple sources (mesh-level, namespace-level and workload-level).

The command also supports reading from a standalone config dump file with flag -f.`,
		Example: `  # Check AuthorizationPolicy applied to pod httpbin-88ddbcfdd-nt5jb:
  istioctl x authz check httpbin-88ddbcfdd-nt5jb

  // singularResource is the singular name of the resource.  This allows clients to handle plural and singular opaquely.
  // For many clients the singular form of the resource will be more understandable to users reading messages and should be used when integrating the name of the resource into a sentence.
  // The command line tool kubectl, for example, allows use of the singular resource name in place of plurals.

	for _, f := range args {
		var r *os.File

		// Handle "-" as stdin as a special case.
		if f == "-" {
			if isatty.IsTerminal(os.Stdin.Fd()) && !isJSONorYAMLOutputFormat() {
				fmt.Fprint(cmd.OutOrStdout(), "Reading from stdin:\n")
			}
			r = os.Stdin
			readers = append(readers, local.ReaderSource{Name: f, Reader: r})
			continue
		}

		fi, err := os.Stat(f)
		if err != nil {
			return nil, err
		}

	if !ok {
		err = fmt.Errorf("error reading plugin list from CNI config")
		return
	}
	return
}

// Given the raw plugin interface, return the plugin asserted as a map[string]interface{}
func GetPlugin(rawPlugin any) (plugin map[string]any, err error) {
	plugin, ok := rawPlugin.(map[string]any)
	if !ok {
		err = fmt.Errorf("error reading plugin from CNI config plugin list")
		return
	}
	return

# Controllers

Istio has a variety of [controllers](https://kubernetes.io/docs/concepts/architecture/controller/), which basically watch some inputs and do something.
This can be reading from Kubernetes and writing other objects back, writing to proxies over XDS, etc.

Unfortunately, writing controllers is very error prone, even for seemingly simple cases.
To work around this, Istio has a variety of abstractions meant to make writing controllers easier.

## Clients

If you install with `helm install istio-gateway istio/gateway`, resources will be named `istio-gateway` and the `selector` labels set to:

```yaml
app: istio-gateway
istio: gateway # the release name with leading istio- prefix stripped
```

If your existing installation doesn't follow these names, you can override them. For example, if you have resources named `my-custom-gateway` with `selector` labels
`foo=bar,istio=ingressgateway`:

	viper.SetConfigName(configName)
	viper.SetConfigType(configType)
	viper.AddConfigPath(configPath)
	viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
	err := viper.ReadInConfig()
	// Ignore errors reading the configuration unless the file is explicitly customized
	if root.IstioConfig != defaultIstioctlConfig {
		return err
	}

	return nil
}

func init() {