ko uses "go" as default GOROOT, causing build errors

[antoineco]

Description

ko uses "go" as GOROOT when GOROOT is not exported in the environment, instead of defaulting to $(go env GOROOT). This prevents builds from happening.

In the previous version, the error message was quite explicit: "go: cannot find GOROOT directory: go".

Now, in 0.6.0, the error is much more ambiguous: importpath "ko://knative.dev/serving/cmd/controller" is not supported.

ko version

$ ko  version
0.6.0

How to reproduce

Example, inside https://github.com/knative/serving/

$ printenv GOROOT  # empty

$ ko publish -L ./cmd/controller  # failure
2020/10/07 12:41:33 failed to publish images: importpath "ko://knative.dev/serving/cmd/controller" is not supported

$ export GOROOT="$(go env GOROOT)"

$ printenv GOROOT
/usr/local/go

$ ko publish -L ./cmd/controller  # success
2020/10/07 12:45:13 Using base gcr.io/distroless/static:nonroot for knative.dev/serving/cmd/controller
2020/10/07 12:45:15 Building knative.dev/serving/cmd/controller for linux/amd64
[...]

Temporary workaround

Add this line to your .*shrc file:

export GOROOT="${GOROOT:-$(go env GOROOT)}"

[mattmoor]

I think @scothis has an open issue for this, and I think @jonjohnsonjr has the most context on this issue.

[scothis]

@mattmoor #106

[antoineco]

@scothis do I understand correctly that ko just needs to be rebuilt (e.g. via go get) for GOROOT to default to the expected value?

[mattmoor]

Unfortunately go get ignores replace directives in go.mod, so I'd recommend go install.

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[jonjohnsonjr]

I believe this is resolved by #303

Please let me know if that is not the case.

[xtreme-sameer-vohra]

I believe this is resolved by #303

Please let me know if that is not the case.

I believe I ran into the same issue using ko v0.7.2 after bumping go to a new 1.15.x patch using homebrew. Building ko locally with the fix solved it.

[sebgoa]

Yes, this is still an issue in 0.7.0

[jonjohnsonjr]

@sebgoa as of v0.8.0, this now prints a warning, does the "right" thing, and includes instructions for making that warning go away (by setting GOROOT explicitly).

My intention is to remove the need for this warning before cutting v0.9.0, as described in #305

If you're still having issues in v0.8.0, let me know.

[sebgoa]

I realised that I ran into this because the Installation section in the README makes you install 0.7.0 binary, hence I did not get the warning. I am not sure if it is intentional, so I will leave it to you to update the README to the latest 0.8 release...