[]string{"fields", "should", "serial_number", "expires", "valid", "type", "proxy"},
				secretDiffColumns...),
			unexpected: []string{"alligator", "certdata"},
		},
		{
			name:   "test JSON output with a single secret diff",
			format: JSON,
			diffs: []SecretItemDiff{
				{
					Agent: "alligator",
					Proxy: "proxy",
					SecretItem: SecretItem{
						Name:        "fields",

			expectedString: "unable to retrieve Pod: pods \"invalid\" not found",
			wantException:  true, // "istioctl proxy-config clusters invalid" should fail
		},
		{ // listeners invalid
			args:           strings.Split("listeners invalid", " "),
			expectedString: "unable to retrieve Pod: pods \"invalid\" not found",
			wantException:  true, // "istioctl proxy-config listeners invalid" should fail
		},
		{ // logging empty

      }

    /**
     * Sets the HTTP proxy that will be used by connections created by this client. This takes
     * precedence over [proxySelector], which is only honored when this proxy is null (which it is
     * by default). To disable proxy use completely, call `proxy(Proxy.NO_PROXY)`.
     */
    fun proxy(proxy: Proxy?) =
      apply {
        if (proxy != this.proxy) {
          this.routeDatabase = null
        }

        Proxy proxy = repository.getProxy();
        if (proxy != null) {
            if (proxy.getUserName() != null) {
                int hash = (proxy.getUserName() + proxy.getPassword()).hashCode();
                buffer.append(hash).append('@');
            }
            buffer.append(proxy.getHost()).append(':').append(proxy.getPort()).append('>');
        }

  @Throws(IOException::class)
  private fun connectSocket() {
    val rawSocket =
      when (route.proxy.type()) {
        Proxy.Type.DIRECT, Proxy.Type.HTTP -> route.address.socketFactory.createSocket()!!
        else -> Socket(route.proxy)
      }
    this.rawSocket = rawSocket

    // Handle the race where cancel() precedes connectSocket(). We don't want to miss a cancel.

    defaultConfig:
      ### ADVANCED SETTINGS #############
      # Where should envoy's configuration be stored in the istio-proxy container
      configPath: "/etc/istio/proxy"
      binaryPath: "/usr/local/bin/envoy"
      # The pseudo service name used for Envoy.
      serviceCluster: istio-proxy
  values:
    global:

    * これは、同じTLS Termination Proxyが証明書の更新処理も行う場合に非常に便利な理由の1つです。
    * そうでなければ、TLS Termination Proxyを一時的に停止し、証明書を取得するために更新プログラムを起動し、TLS Termination Proxyで証明書を設定し、TLS Termination Proxyを再起動しなければならないかもしれません。TLS Termination Proxyが停止している間はアプリが利用できなくなるため、これは理想的ではありません。


アプリを提供しながらこのような更新処理を行うことは、アプリケーション・サーバー（Uvicornなど）でTLS証明書を直接使用するのではなく、TLS Termination Proxyを使用して**HTTPSを処理する別のシステム**を用意したくなる主な理由の1つです。

## まとめ

import java.net.HttpURLConnection
import java.net.Proxy
import okhttp3.HttpUrl
import okhttp3.Request

object RequestLine {
  /**
   * Returns the request status line, like "GET / HTTP/1.1". This is exposed to the application by
   * [HttpURLConnection.getHeaderFields], so it needs to be set even if the transport is
   * HTTP/2.
   */
  fun get(
    request: Request,
    proxyType: Proxy.Type,
  ): String =
    buildString {

      annotations:
        prometheus.io/path: /stats/prometheus
        prometheus.io/port: "15020"
        prometheus.io/scrape: "true"
        proxy.istio.io/config: '{ "holdApplicationUntilProxyStarts": true }'
        sidecar.istio.io/status: '{"initContainers":["istio-init"],"containers":["istio-proxy"],"volumes":null,"imagePullSecrets":null,"revision":"default"}'
      creationTimestamp: null
      labels:
        app: hello
        tier: backend

This document describes the high level architecture of the Istio control plane, Istiod.
Istiod is structured as a modular monolith, housing a wide range of functionality from certificate signing, proxy configuration (XDS), traditional Kubernetes controllers, and more.

## Proxy Configuration

Istiod's primary role - and most code - is to dynamically configure proxies (Envoy sidecars and ingress, gRPC, ztunnel, and more). This roughly consists of 3 parts: