Override ubi9's gotoolchain from local to auto

[nvtnlucie]

This change allows Renovate to renovate different versions of Go. There was also a suggestion to predownload different toolchains, however when i tested this agains dependency from go1.21 and go1.23 it did not redownload anything, can I skip it?

[gnaponie]

Unfortunately I'm not expert enough in go to reply. Maybe @qixiang and @querti know it better.
Would you be able to link the documentation reference where you saw these info? So I can check it and give me my 50 cents on this.

[qixiang]

The ref doc: https://go.dev/doc/toolchain

when i tested this agains dependency from go1.21 and go1.23 it did not redownload anything, can I skip it?

Not sure how did you test it, in theory, if you're running with any go <= 1.23, it should download the newer version of go toolchain in go 1.23 project.

From above linked doc:

For example, when using the go command bundled with Go 1.21.3 in a main module that says go 1.21.9, the go command finds and runs Go 1.21.9 instead. It first looks in the PATH for a program named go1.21.9 and otherwise downloads and caches a copy of the Go 1.21.9 toolchain.

[nvtnlucie]

@qixiang Hmm, I built the image and let Renovate update 2 go.mod files, each with different version written at the top. Renovate does not complain about not having the correct version, nor does it download the latest one, I dont think it requires running go at all.
I am looking at the managers again, there is option to enable to run go mod tidy after an update, maybe thats the problematic part? Ill retest it.

[staticf0x]

The GOTOOLCHAIN=auto seems to work, it downloads the required Go toolchain version automatically if the system doesn't provide the required version.