The description is not very clear;
I'm assuming the application is a nodejs application ( server ! ), requiring access to network
and possible some local file systems.
I'm also assuming that the delivery will be the dockerfile, based on a standard
linux image.
I'll split the deliverable in two parts:
1: Delivering a basic working dockerfile , along with any changes in the application if required.
2: Thorough testing, and documenting the dockerfile and any other artifacts.