Missing package in 1.18

[ocket8888]

golang:1.17.8-alpine came with the git executable - presumably to accommodate go get - but golang:1.18-alpine does not - presumably because of the breaking change to go get that accompanied the new version.

[yosifkit]

git in the PATH? It is not installed in the alpine based image on purpose (and never has been).

Duplicate of #345/#347 (most recently), but see also #250 (comment); #119, #140, #153, #157, #166, #198, #209, #230, #239, #241, #251, #328.

[ocket8888]

I have an image that worked using golang:1.17.8-alpine and now fails to build an executable at runtime having changed only that base image with:

go: missing Git command. See https://golang.org/s/gogetcmd
        error obtaining VCS status: exec: "git": executable file not found in $PATH
 	Use -buildvcs=false to disable VCS stamping.

I assumed this was because git used to be in the $PATH, but it could just be a misleading error message

[ocket8888]

I went back to 1.17.8 and confirmed that there's no git anywhere on the image filesystem. So I'm not sure what was actually broken.

[ocket8888]

Found the exact command in the image's CMD that used to work but now doesn't:

go build --gcflags "all=-N -l" .

a go build that used to work no longer does

[dagood]

Here's a simple reproduction:

docker run -it --rm golang:1.18-alpine sh -c '
  mkdir /app; cd /app
  echo "package main;func main(){}" > main.go
  go mod init example
  mkdir .git
  echo ---
  go build .'

go: creating new go.mod: module example
go: to add module requirements and sums:
        go mod tidy
---
go: missing Git command. See https://golang.org/s/gogetcmd
error obtaining VCS status: exec: "git": executable file not found in $PATH
        Use -buildvcs=false to disable VCS stamping.

As it says, running go build -buildvcs=false . fixes it. Deleting .git also fixes it.

It looks like the new VCS status embedding feature in go 1.18 requires git, and instead of silently skipping buildvcs when git isn't available, it shows an error.

• cmd/go: "go test" seems to now require git due to -buildvcs golang/go#51723
• cmd/go: add (and default to) -buildvcs=auto golang/go#51748

[ocket8888]

But that's impossible, the Go team knows that it's unacceptable to ever make a breaking change under any circumstances 🙄

More seriously it looks from that bottom comment like they're open to fixing this - but at any rate it's not an issue with this Docker image, but an upstream problem. I'll take it up with them. Thanks.

[tianon]

If you really don't need .git for your builds at all, you can add .git to .dockerignore too 👀

[abursavich]

@ocket8888, please consider re-opening this issue.

There is a new std package in go 1.18, debug/buildinfo, which requires git in order to stamp the version control info on the binary (svn, hg, and bzr might be required too?). It's unfortunate that this may unnecessarily break some use cases (e.g. tests), but I think it's reasonable to expect that the official docker image should support the std packages of the language.

[ocket8888]

If you really don't need .git for your builds at all, you can add .git to .dockerignore too 👀

No, the source directory is mounted as a volume, not loaded into the build context, so that's unfortunately not an option.

It's unfortunate that this may unnecessarily break some use cases (e.g. tests), but I think it's reasonable to expect that the official docker image should support the std packages of the language.

I'll re-open if you want, but for the record I think Go ought to walk this back instead. And they yet might. No idea how long that would be, though, or if 1.18.0 would ever see it anyway.

[codemicro]

I'll re-open if you want, but for the record I think Go ought to walk this back instead.

The Go team is adding a -buildvcs=auto option that'll be backported to 1.18 that will implicitly disable VCS stamping if no VCS can be found.

[abursavich]

It'll be great if VCS binaries are not a hard dependency of the go tool, but I still think they should still be present in the official golang 1.18+ images.

[ocket8888]

They probably should be. Otherwise it's a feature of the tool for which the image is built that isn't directly supported by that image. Which is unusual. You could add -no-vcs suffix tags for every version from now on, but that seems like a lot of work and I'd wager hardly any users would actually switch to it.

[tianon]

The non-Alpine (Debian-based) images do contain all the tools -- they're FROM buildpack-deps:XXX-scm, which already includes most of the SCMs from https://github.com/golang/go/wiki/GoGetTools (by design).

Quoting again from the Alpine section of https://hub.docker.com/_/golang (https://github.com/docker-library/docs/tree/0b63293e37969498f85b48a9bcb5908993052ddc/golang#golangversion-alpine):

This variant is highly experimental, and not officially supported by the Go project (see golang/go#19938 for details).
...
To minimize image size, additional related tools (such as git, gcc, or bash) are not included in Alpine-based images. Using this image as a base, add the things you need in your own Dockerfile (see the alpine image description for examples of how to install packages if you are unfamiliar). See also docker-library/golang#250 (comment) for a longer explanation.

The Alpine variants exist specifically to be much smaller than the default base, not to be a full-featured 100% complete environment ready-for-use like the non-Alpine variants are.

[ocket8888]

Fair enough.

[tianon]

(Closing per #415 (comment) ❤️)