t.Fatalf("unexpected err: %v", err)
	}
	proxy, err := http.ProxyFromEnvironment(req)
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if proxy == nil {
		t.Skip("test skipped as ProxyFromEnvironment already initialized in environment without defined HTTP proxy")
	}
	t.Log("http.ProxyFromEnvironment is usable, continue executing test")
}

func TestKubeletVersionCheck(t *testing.T) {

	conn net.Conn

	// Dialer is the dialer used to connect.  Used if non-nil.
	Dialer *net.Dialer

	// proxier knows which proxy to use given a request, defaults to http.ProxyFromEnvironment
	// Used primarily for mocking the proxy discovery in tests.
	proxier func(req *http.Request) (*url.URL, error)

	// pingPeriod is a period for sending Ping frames over established
	// connections.

	}

	// For more details about various values used here refer
	// https://golang.org/pkg/net/http/#Transport documentation
	tr := &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		DialContext:           dialContext,
		MaxIdleConnsPerHost:   maxIdleConnsPerHost,
		WriteBufferSize:       WriteBufferSize,
		ReadBufferSize:        ReadBufferSize,
		IdleConnTimeout:       15 * time.Second,

		// modified.
		r := *req
		*r.URL = *req.URL
		req = &r
		tlsConfig.InsecureSkipVerify = true
		req.URL.Scheme = "https"
	}

	transport := http.Transport{
		Proxy:           http.ProxyFromEnvironment,
		TLSClientConfig: tlsConfig,
	}

	return transport.RoundTrip(req)

// connect happens.
func newClient(endpoint string) NetLocker {
	u, err := url.Parse(endpoint)
	if err != nil {
		panic(err)
	}

	tr := &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		MaxIdleConnsPerHost:   1024,
		WriteBufferSize:       32 << 10, // 32KiB moving up from 4KiB default
		ReadBufferSize:        32 << 10, // 32KiB moving up from 4KiB default
		IdleConnTimeout:       15 * time.Second,

	}

	args := &OperatorDNS{
		Endpoint: endpoint,
	}
	for _, setter := range setters {
		setter(args)
	}
	args.httpClient = &http.Client{
		Transport: &http.Transport{
			Proxy: http.ProxyFromEnvironment,
			DialContext: (&net.Dialer{
				Timeout:   3 * time.Second,
				KeepAlive: 5 * time.Second,
			}).DialContext,
			ResponseHeaderTimeout: 3 * time.Second,
			TLSHandshakeTimeout:   3 * time.Second,

	if t.Proxy == nil || isDefault(t.Proxy) {
		// http.ProxyFromEnvironment doesn't respect CIDRs and that makes it impossible to exclude things like pod and service IPs from proxy settings
		// ProxierWithNoProxyCIDR allows CIDR rules in NO_PROXY
		t.Proxy = NewProxierWithNoProxyCIDR(http.ProxyFromEnvironment)
	}
	// If no custom dialer is set, use the default context dialer

			checkNewCertificateAndRotate()
			return hasCert.Load(), nil
		}, stopCh)
	}

	clientConfig.Transport = utilnet.SetTransportDefaults(&http.Transport{
		Proxy:               http.ProxyFromEnvironment,
		TLSHandshakeTimeout: 10 * time.Second,
		TLSClientConfig:     tlsConfig,
		MaxIdleConnsPerHost: 25,
		DialContext:         d.DialContext,
	})

// or might be using self-signed certificates.
var impatientInsecureHTTPClient = &http.Client{
	CheckRedirect: checkRedirect,
	Timeout:       5 * time.Second,
	Transport: &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
		},
	},
}

var securityPreservingDefaultClient = securityPreservingHTTPClient(http.DefaultClient)

		refreshIntervalOnFailure: refreshIntervalOnFailure,
		retryInterval:            retryInterval,
		httpClient: &http.Client{
			Transport: &http.Transport{
				Proxy:             http.ProxyFromEnvironment,
				DisableKeepAlives: true,
			},
		},
	}

	caCertPool, err := x509.SystemCertPool()
	caCertsFound := true
	if err != nil {
		caCertsFound = false