5. Creating and Managing vApps : 5.4 vApp Deployment Readiness : 5.4.4 vApp Lifecycle Considerations
5.4.4 vApp Lifecycle Considerations
You must understand vApp dependencies and verify that business requirements can continue to be fulfilled throughout the lifecycle.
Providing Infrastructure as a Service (IaaS) requires new approaches to workload management, which can be disruptive, but there are many benefits (see Operating a VMware vCloud for information about proven approaches for managing vCloud environments). VMware vCloud Director supports delivery of Infrastructure as a Service.
When using vCloud Director, one common concern is the underlying network configuration implemented to support deployed vApps, in particular, how the configuration impacts network connectivity outside the vCloud and the associated impact on application dependencies.
To effectively design a new vApp, you must have a detailed understanding of application behavior and external dependencies. vCloud Director leverages the Edge networking appliance, which offers DHCP, firewall, NAT, static routing, and VPN capabilities that can be configured and managed from within vCloud Director. Various scenarios that illustrate vApp network configurations, with and without Edge, are described in Section 5.4.1.
The following figure shows an Edge appliance being used to fence a vApp so that it can be isolated, yet it uses NAT for connectivity to and from external resources. This configuration can present challenges for agent-based solutions, such as backup or antivirus updates.
Figure 17. Sample vApp Backed by a Fenced Network
In this example, private addressing is used behind the Edge appliance, and a single NAT address is used to map a single public IP address for the web-based application. Access to the vApp from outside the vCloud goes through the public IP address on port 80, which is redirected to the Web server using its internal private IP address. In some cases an application requires an agent installed on the virtual machines inside the vApp.