DotNet SDK Default Paths

[baronfel]

First pass at unifying the default paths to the system-wide install locations.

Outstanding questions:

• Do we want to take on global.json enhancements here?
• If so, where should global.json be consulted?

Related to #1961

[baronfel]

This failed during the packaging steps for the exact reasons mentioned in the attached discussion: The packaging was done with the C:\Program Files\dotnet version of dotnet and not the local one.

[matthid]

Actually the problem is just that we assumed that we install into the default directory here:

https://github.com/baronfel/FAKE/blob/05b844724cee075f318c12e45e17d9b60367042c/src/app/Fake.DotNet.Cli/DotNet.fs#L622-L628

I guess this needs to be changed now as the assumption is no longer true

[baronfel]

Ah I see, the install needs to pass that install dir arg, yeah

[matthid]

No actually I think the installer should install in users directory as otherwise this only leads to permission problems. So we basically have two "defaults", one where we look for the global installation and one where we look for user-local installations.

[baronfel]

If we do that then we have to then do additional probing across the two locations to check which one (or both?) has the intended version. Which again, is hard to reconcile with PATH. Are we sure that permissions will be a big deal?

[matthid]

Maybe there is another bug as it seems to ignore the install parameter at the moment

[matthid]

Are we sure that permissions will be a big deal?

Yes there will be people on corporate environments who will thank you

[matthid]

ping :)

[matthid]

Sorry, please just merge release/next I already fixed that (and actually made the same mistake :D )

[baronfel]

Hahaha we would make the worst C# devs 😄

[matthid]

@baronfel @TheAngryByrd @kblohm What do you think about 30bf7e8 ? The basic idea is that the "global.json" topic is orthogonal to installing the SDK with FAKE.

This commit

• introduces a install FromGlobalJson-Api which allows to manage the version in global.json
• writes global.json before calling dotnet SDK (and deletes it afterwards) to make the SDK choose the correct version
• Errors out if global.json exists and doesn't match
• We search and try more directories for installed SDK versions

[kblohm]

That does probably solve a lot of the versioning problems 👍
Some comments:

• You might want to add withVersion functions similair to withEnvironment to all the options or at least to the options-module (preferSystemInstall is also in the options-module and i feel like these kinda belong in the same category)
• It looks like this would not work when there is a global.json file already that is used for something other than specifying the dotnet version (for example https://github.com/onovotny/MSBuildSdkExtras#using-the-sdk)
• It might be nice to have the option to create a global.json when installing a version with fake, so that the installed version gets used for everything afterwards

[matthid]

You might want to add withVersion

I'm not sure you want to use the Version option directly, my suggestion would be to always use the result of the install API.

when there is a global.json file

We don't replace an existing file so we either exit with an error or run with the wrong version ... Good catch

It might be nice to have the option to create a global.json when installing a version with fake

For now it's easier to let users create it, because for this we would need a way to figure out if we wrote the file (such that we can overwrite it later if needed). But yeah makes sense.