Refactoring and further optimization

[remz1337]

As I'm getting more familiar with all the functions and utilities in this repo, I see a few opportunities of improvements. I would like to know your thoughts on these:

1. Avoid code duplication:
   • for example, the msg_info function is defined both in build.func and install.func
   • This can be avoided by creating a common.func file with common functions that can be loaded at the beginning of build.func and install.func
2. Use default_settings function inside an app's script only to superseed a base configuration
   • Instead of copy/pasting a bunch of options that rarely changes such as MTU="", SD="", NS="" and MAC="", the entire set of options could be defined somewhere else (say a base_settings function in build.func), so by calling default_settings after loading the base settings, scripts would only need to specify what is specific (RAM, CPU...)
3. Use environment variables to keep track of common options used across all services/LXC

• For 2 and 3:
  • This would also facilitate using the new APT_CACHER and APT_CACHER_IP options since people would only need to set them up in the base settings/environment variables
  • Nice to have: Add a menu to consult/update those variables

[tteck]

Nope

[tteck]

I could hide a bunch of variables, gotta think about making it easier to vet the code for a particular application