Add app config file support

[avive]

Implement support for app configuration via a config file, and write tests for app configs using a file.
Choose TOML or YAML as file format and integrate with cli1.v1

[avive]

Refs:
https://github.com/toml-lang/toml
https://github.com/urfave/cli

[jreyeshdez]

I am working on this feature and came across same issue as pointed here:
urfave/cli#599

It looks like it is a bug and still open

[y0sher]

Hi @jreyeshdez,
I'm also working on this here : #20, I tried to overcome some limitations caused by the cli parser bugs.
I'll push it to a branch and edit this comment so we can combine forces :)

we might want to merge those issues @avive ?

Edit:
you can look at the code here https://github.com/y0sher/go-spacemesh/tree/config
I took care of uint loading with a map and a simple casting func.
The problem is as soon as we let a duration value inside there's a type mismatch error because it isn't a duration. (it's either a string or an int ex: "24h5m" or 86400000 (miliseconds) )
for some reason even though I took care of parsing durations by ourselves, the rest string and boolean flags get messed up.
if we comment out durations everything works great.
some other issues :

• We must use the names we use as flag names in the toml file. that means we can't use multiple names as 'flagname, fn' for command line parsing
• Using sections doesn't work

I'm thinking maybe we should drop using the cli for that and load a config file by ourself then apply it to flags. to make sure all types are working and everything is consistent without relying on the cli package.

Have any thoughts or ideas ? @jreyeshdez @avive

[avive]

@y0sher - looking into this today

[avive]

@y0sher - do you mind opening a PR from your forked code so I can have a look and comment? Just please mark it as WIP

[avive]

Thanks @y0sher for the good work on getting this done!