In one embodiment, an initialization script including instructions to define a value of a parameter at a cloned virtual machine instance is generated and stored at a virtual disk of a source virtual machine instance. The value of the parameter at the cloned virtual machine instance is different from the value of the parameter at the source virtual machine instance. An image of the virtual disk is then sent to a virtual machine module. The cloned virtual machine instance is instantiated at the virtual machine module based on the image of the virtual disk.