Configuration file with configuration options

[yannjor]

Would be nice for example to configure comment styles for different file extensions in a config file, instead of having to modify the source code. The config file could also be used to configure paths to ignore, or to configure the patterns that determine whether a file already has a license header.

Implementations of these features are included in the Nokia fork of addlicense. If you are interested in pulling only some parts, see the different branches there.

[willnorris]

Just leaving a note here that if we did want to add support for this, https://github.com/peterbourgon/ff might be a good approach that doesn't require much additional work. We'd also get support for environment variables for free, for those users that prefer that approach.

(for what it's worth, ff is used by https://github.com/sourcegraph/sourcegraph and https://github.com/tailscale/tailscale, that I know of off the top of my head)