How to use puppet to install and configure custom app? - puppet

Question

My goal is for my users to start with a base Linux machine, install puppet, clone my GitHub repo and run puppet apply myapp.pp, this should then using puppet:
1) configure the system with any pre-requisites etc,
2) git clone another repo that contains my application code
3) compile, install and configure my application.
The specifics of getting Puppet to do 1, 2 and 3 seem fairly straight-forward, but what I cannot understand is if I should write a Puppet Module, or just a Manifest?
I started with a Manifest, but templating did not seem to work, puppet always complained it could not find the .erb files. That work can be seen here: https://github.com/adamretter/exist-puppet.
After making some enquiries, I was told that I needed to refactor my code into a Puppet module, which I have started to do here: https://github.com/adamretter/puppet-exist.
However there seems to be no way to run puppet apply on a module, so how do I achieve what I am looking for? Someone said that I need to call my module from a small .pp file stub, but I cannot see how to do that in the same git repo, as when I try to include it, it says it cannot find my module?
Are there any good examples where this is kinda thing is already done?
I have tried to follow the Puppet documentation, but it seems to make leaps or assume too much: https://docs.puppetlabs.com/guides/module_guides/bgtm.html

Answer 1

First of all, post your errors when you run a command, that will help debug the problem. Here are a few tips you can follow:
To apply a standalone module, you need to have the following structure :
<modulename>/manifests/init.pp
/<subname>.pp
init.pp content may look like this :
class <modulename> {
notify {"New module using Puppet apply":}
include <modulename>::<subname>
}
subname.pp content may look like this :
class <modulename>::<subname> {
# Some manifest
}
All these files need to be physically on the client machine in order for puppet apply to work. And you need to be in the parent directory of <modulename> while running puppet apply command. You can do,
puppet apply -e 'include <modulename>'
As #FelixFrank suggested, you can give the modulepath as an argument.
puppet apply -e 'include <modulename>' --modulepath=/path/to/modules