Spago tries to create a global cache when `-c skip` is used

[ursi]

Spago will still try to create a global cache when -c skip/--global-cache skip is used. This tripped me up when trying to use spago to build something with nix, as HOME is set to /homeless-shelter (which doesn't exist) and spago tries to create it (which it doesn't have permission to do).

[ursi]

Okay according to the README it looks like you're supposed to use this flag with an =. Using --global-cache=skip I get the same behaviour. Using -c=skip I get the help text.

[f-f]

Hi @ursi!

I have a few points about this:

• you can use long flags with both = or spaces, i.e. both --global-cache skip and --global-cache=skip are valid
• what Nix is doing here doesn't seem nice, as I feel it makes sense that the HOME directory for the user exists and it's writable. In any case, you can always change the location of the cache by setting the XDG_CACHE_HOME envvar. This is how we get its location:
  

  spago/src/Spago/GlobalCache.hs

  Lines 145 to 154 in 6258ac6

  	-- | Directory in which spago will put its global cache
  	-- `getXdgDirectory XdgCache` tries to find the folder pointed by
  	-- `$XDG_CACHE_HOME`, otherwise it uses:
  	-- - (on Linux/MacOS) the folder pointed by `$HOME/.cache`, or
  	-- - (on Windows) the folder pointed by `LocalAppData`
  	getGlobalCacheDir :: (MonadIO m, HasLogFunc env, MonadReader env m) => m FilePath.FilePath
  	getGlobalCacheDir = do
  	globalCache <- liftIO $ getXdgDirectory XdgCache "spago" <|> pure ".spago-global-cache"
  	assertDirectory globalCache
  	pure globalCache

• I did notice before that the global cache would still be somehow doing things even when one wanted to disable it, so I included a fix for this in my refactoring in Refactor internal environments handling #705. We should now not have anything to do with it when using -c skip

[ursi]

Yes, I had figured out that trick, sorta - I set HOME. Thanks for the fixes!

[f-f]

You're welcome 🙂