1. A method, implemented at a computer system that includes one or more processors, of creating a single deployment package for deploying a deployable application entity to a plurality of different target environments, the method comprising: identifying a configuration dataset defining one or more configuration parameters for configuring the deployable application entity; identifying a plurality of target environments into which the application entity is deployable, including identifying a plurality of different definition datasets, each definition dataset corresponding to one of the plurality of target environments, each definition dataset defining one more unique configuration settings specific to its corresponding target environment; during a build time, transforming the configuration dataset for each of the plurality of target environments, based on the definition dataset corresponding to each of plurality of target environments, to create a plurality of different transformed configuration datasets that each corresponds to one of the target environments and that each includes a combination of the configuration dataset and one of the definition datasets; and packaging the plurality of transformed configuration datasets with the deployable application entity to create a single deployment package that is deployable to each of the plurality of different target environments, each target environment being enabled to use its corresponding transformed configuration dataset to configure the deployable application entity for operation within the target environment.