1. 关于vapp

APP是由VMware发起的、一个对于云操作系统进行优化的软件解决方案。一个vAPP就是由一个或者多个虚拟机构成的逻辑体或者说逻辑容器，可以作为一个单位来进行管理。vAPP是一种类似于资源池的容器，可以包含一个或多个虚拟机。vAPP还可以与虚拟机共享某些功能。可以打开和关闭vAPP电源，还可以对其进行克隆。所以vApp就是一个逻辑容器，就好像一个文件夹一样，它本身并没有提供高级的功能。不是像以前理解的的那样，vAPP是使用VMware自己的开发工具开发的针对VMware虚拟平台的应用程序。vAPP只是一个简单的虚拟机的容器。

vAPP通过将n层应用程序封装到一个vAPP的实体中，简化了多个虚拟机中此类应用程序的部署和后续管理。vAPP不仅封装虚拟机，还封装其相互依存关系和资源分配情况，从而实现一步完成整个应用程序的电源操作、克隆、部署和监视。vCenter Server当前还支持创建和运行vAPP，并可根据开放式虚拟化格式（OVF）1.0标准对其进行导入和导出。

vAPP元数据驻留在vCenter Server的数据库中，因此可以在多个ESXi主机之间开发vAPP。如果清除vCenter Server数据库，或者从vCenter Server移除包含vAPP的独立ESXi主机，则可能会丢失此信息。

2. vapp的创建

参考：
https://blog.51cto.com/capfzgs/1584755

3. vapp与virtual appliance的区别

A vApp is a preconfigured virtual machine that packages applications and parameters that define operational details.A vApp packages applications with their required operating systems.

A vApp allows disparate virtual machines to work together in a stack as an application, and supports cloud-computing architectures. You can nest vApps within vApps, set up VMware resource pools, and deploy new vApps based on existing ones. VMware vApps operate on the Open Virtualization Format (OVF) standard and vApps are exported in OVF format.

Virtual Private Cloud OnDemand displays information about the vApp that contains each virtual machine; however, you do not select or manage vApps when you create a virtual machine in Virtual Private Cloud OnDemand. You manage vApps by using vCloud Director.

See Working with vApps in the vCloud Director User's Guide for information.

Managing vApps in vCloud Director allows you to save a vApp as a vApp template in your catalog. See Working with vAppTemplates in the vCloud Director User's Guide for information.

See also Create a Virtual Machine from a Template. In Virtual Private Cloud OnDemand, you use templates when creating virtual machines. A VMware template (also called a golden image) is a model copy of a virtual machine from which you can clone or deploy more virtual machines.

Details: Differences Between vApps and Virtual Appliances
A virtual appliance is a generic term for an application delivered as a prebuilt unit. More specifically, a virtual appliance is a virtual machine image file consisting of a pre-configured operating system environment and a single application. The purpose of a virtual appliance is to simplify delivery and operation of an application. To this end, only necessary operating system components are included.

A virtual appliance can be deployed as a virtual machine or a subset of a virtual machine running on virtualization technology, such as VMware Workstation. Deploying an application as a virtual appliance can eliminate problems with installation and configuration, such as software or driver compatibility issues.

“vApp” is a VMware specific term for an application encapsulated within a vApp pool (which works in a hosted environment and on hypervisors). A vApp can define a number of specific things about an appliance, such as performance and resource pools, IP address allocation policies, or firewall requirements.