@senthilkumaran I also suggest you check out the sample apps which Cloudron made and are available for testing proof of concept and as a base for your own package(s).
Also look on git.cloudron.io : there are many custom apps there from users (not Cloudron staff). Those can give you a good idea of how people approach the task of packaging, and i particular the task of separating read only /app/code and read write /app/data.