return Class.forName("com.google.apphosting.api.ApiProxy")
              .getMethod("getCurrentEnvironment")
              .invoke(null)
          != null;
    } catch (ClassNotFoundException e) {
      // If ApiProxy doesn't exist, we're not on AppEngine at all.
      return false;
    } catch (InvocationTargetException e) {
      // If ApiProxy throws an exception, we're not in a proper AppEngine environment.

      return Class.forName("com.google.apphosting.api.ApiProxy")
              .getMethod("getCurrentEnvironment")
              .invoke(null)
          != null;
    } catch (ClassNotFoundException e) {
      // If ApiProxy doesn't exist, we're not on AppEngine at all.
      return false;
    } catch (InvocationTargetException e) {
      // If ApiProxy throws an exception, we're not in a proper AppEngine environment.

SIG Storage is also introducing the following new storage features as alpha in Kubernetes 1.18:
- Windows CSI Support: Enabling containerized CSI node plugins in Windows via new [CSIProxy](https://github.com/kubernetes-csi/csi-proxy)

### Container Storage Interface graduations

CSI support for Windows nodes moves to GA in the 1.22 release. In Kubernetes v1.22, Windows privileged containers are only an alpha feature. To allow using CSI storage on Windows nodes, [CSIProxy](https://github.com/kubernetes-csi/csi-proxy) enables CSI node plugins to be deployed as unprivileged pods, using the proxy to perform privileged storage operations on the node.

		{
			name:            "dual-stack host: defaultEndpoint set to 127.0.0.1:7073",
			proxy:           &dsProxy,
			defaultEndpoint: "127.0.0.1:7073",
			expectedAddr:    "127.0.0.1",
			expectedPort:    7073,
		},
		{
			name:            "dual-stack host: defaultEndpoint set to [::1]:7073",
			proxy:           &dsProxy,
			defaultEndpoint: "[::1]:7073",
			expectedAddr:    "::1",
			expectedPort:    7073,
		},

			d.Authenticate = auth.Authenticate
		}
		if _, err := d.DialWithConn(ctx, conn, "tcp", cm.targetAddr); err != nil {
			conn.Close()
			return nil, err
		}
	case cm.targetScheme == "http":
		pconn.isProxy = true
		if pa := cm.proxyAuth(); pa != "" {
			pconn.mutateHeaderFunc = func(h Header) {
				h.Set("Proxy-Authorization", pa)
			}
		}
	case cm.targetScheme == "https":
		conn := pconn.conn

  ln -s -f "${mount_point}/srv/kubernetes" /etc/srv/kubernetes
  # Directory for kube-apiserver to store SSH key (if necessary).
  mkdir -p "${mount_point}/srv/sshproxy"
  ln -s -f "${mount_point}/srv/sshproxy" /etc/srv/sshproxy

  chown -R etcd "${mount_point}/var/etcd"
  chgrp -R etcd "${mount_point}/var/etcd"
}

# append_or_replace_prefixed_line ensures:
# 1. the specified file exists

* Add orphaning finalizer logic to GC ([#25599](https://github.com/kubernetes/kubernetes/pull/25599), [@caesarxuchao](https://github.com/caesarxuchao))
* GCI-backed masters mount srv/kubernetes and srv/sshproxy in the right place ([#26238](https://github.com/kubernetes/kubernetes/pull/26238), [@ihmccreery](https://github.com/ihmccreery))