1. A method comprising: receiving, by a deployment unit of a computing system, a user selection of a base configuration template storing a base configuration file and a plurality of supplementary configuration templates each storing a respective supplementary configuration file, each supplementary configuration file including a respective tagged element for modifying a corresponding tagged element of the base configuration file, each configuration file storing information on deploying an application program into a runtime execution environment; obtaining an order of applying the supplemental configuration files to the base configuration file, the order indicating that a first supplemental configuration file is to be applied to the base configuration file before a second supplemental configuration file is applied to the base configuration file; merging the base configuration file and the supplemental configuration files by a merge unit of the deployment unit in a plurality of iterations, comprising, in a first iteration, modifying configuration information provided in the base configuration file using the first supplemental configuration file and storing the modified configuration information as a new base configuration file, and then, in a second iteration, modifying configuration information stored in the new base configuration file using the second configuration file; and deploying the application program into the runtime execution environment based on configuration information resulted from the merging.