Allow to disable version update check

[Horgix]

From why I understand from the update warning by the CLI, the strace I ran on it, and the check.go sources, it looks like the CLI send a request to cli-dl.scalingo.io/version everytime to know if it's up-to-date.

It also looks like it's currently not possible to disable this check, and I know that some people don't really like CLI that "call home" (I'm among them, especially when running a --help or --version) 😉

It would be cool to be able to disable it, for example with an environment variable (that's what Hashicorp are doing on Packer). The best would be to have it opt-in but I think you'll prefer to keep it ON by default don't you?

If you're OK with this, I would like to send the PR implementing it 🙂

[Soulou]

Hi there, we're completely ok with this. To be fully transparent we're not doing anything from this call to cli-dl (no stat for instance), its purpose is only to notify when a new version is released, waiting for an auto-upgrade mecanism to be developed. (Which will be disablable ;-))

[Horgix]

I definitely trust you on that and even if you were doing stats on it it wouldn't be that much of a problem anyway. Just thought I would open this since I was surprised to see a --help doing HTTP requests 😄

I just saw #174, #175 and #309 about the auto-upgrade. Definitely not a fan of this and would definitely appreciate if it was possible to disable this kind of thing!

[yannski]

@Horgix you're right, the help command should not do any HTTP requests, there should be a dedicated subcommand for version checking and the auto-upgrade should be disconnectable