Add --prefer-offline / MISE_PREFER_OFFLINE

[hverlin]

Add a --prefer-offline flag / MISE_PREFER_OFFLINE environment variable for a few commands like mise doctor. I imagine this can be useful in various context when the internet speed is low or when one wants a command to return as fast as possible.

This is obviously not going to work with every command (like mise install) however.

[syhol]

Sounds good to me. I like how mise uses network by default but its nice to have an offline mode.

[roele]

I wonder what commands you have in mind for offline support. It seems that neither mise doctor nor mise version do cause issues when offline (and cache is cleared).

[syhol]

Mise install node@latest now uses the network. It would be nice if we had the option to just use whatever is the latest installed version.

[jdx]

well that is how mise use behaves.

[hverlin]

I think this ticket is mainly about changing the behavior so that mise works better when offline. I don't think it's a strange idea to e.g. only rely on the cache if you can't list remote versions for some reason?

I have seen these commands (e.g., mise doctor) hang due to network calls within plugins - which is why I created the discussion in the first place.
A recent example I have here is mise unuse: I see that it does some network calls (even it failed once for me when one of the endpoints used by a plugin was down and could not use the command)

Another comment here mentions that they could not use mise without a working internet connection:
#3935 (comment)

[jdx]

this would likely be a perennial issue trying to maintain. It already has proven difficult to only make requests in proper situations. Often code gets added that makes http requests in places we didn't expect. This also becomes a challenge because any time we would've performed a request we need to create an alternate code path that is able to function without http.

A general "--prefer-offline" flag is probably unrealistic. We'd probably have to work on individual commands. I have done this already with commands like mise ls and mise hook-env which shouldn't use http at all really. Things like mise install I think is far less important since a real install would obvious require http. It also would require http depending on whether or not a lockfile is in use or if full versions are specified—partial versions would require http so mise can know if a new version is available to install.

What would likely be easier for us is a --offline flag that fails hard whenever it does any request—though mise can perform requests indirectly like in plugins that it wouldn't be able to block.

Anyhow, I'm open to adding this but I also don't think the juice is worth the squeeze outside of things that run indirectly like mise hook-env, shims, or commands like mise ls that seem like they should only perform "locally" unlike mise install. My understanding is that when it comes to those we generally avoid http but I wouldn't be surprised if there was a "bug" where http requests are being made.

WIth mise dr I know at least one of the checks is for the mise version which definitely seems like something it should display.