build: CGO_ENABLED=0 ./make.bash does not force default in later runs of cmd/go

[jefferai]

I've been trying to figure out how to make my programs build statically by default without specifying -a -installsuffix cgo -ldflags '-extldflags "-static" -s for every project. I've read through #9344, and supposedly the change to make dynamic builds the default is only for released versions of Go. Accordingly, I tried the following:

1. Install Go onto my system from a package manager
2. Check out go1.5.1 from Git
3. Set GOROOT to point to the checked-out version of Go, and GOROOT_BOOTSTRAP to the system version of Go
4. cd src; ./all.bash -- successful
5. rm -rf $GOPATH/pkg
6. Start a new shell with GOPATH, GOROOT, and PATH all set appropriately. I can verify that I'm using the self-compiled version of Go (which itself was built dynamically), but binaries produced with my self-built Go are still being built dynamically without passing in -a -installsuffix cgo -ldflags '-extldflags "-static" -s

Is this a bug, or did I misinterpret the requirements in #9344?

Thanks!

[ianlancetaylor]

I can't tell if this is a bug report or not. We use the issue tracker for actual bugs and proposed changes. Please ask questions on the golang-nuts mailing list or on https://forum.golangbridge.org/. Thanks.

I can't see what you are referring to in #9344. In any case, when you check out go1.5.1, you are getting a released version of Go. To get a non-released version of Go, you need to check out something that is not a release. But of course those are not supported.

If you build your own version of Go with CGO_ENABLED=0 set in the environment, you should get a version of Go that builds statically by default.

[jefferai]

@ianlancetaylor I couldn't tell if it was a bug either, because I wasn't sure if the workflow that was described was expected to work, or not. After reading what you said, I do think it's at least a documentation issue.

#9344 suggests that the reason for dynamic linking in released versions is because they are installed to system locations that normal users don't have access to change. This is confusing, because this should be a toggle flipped by packagers when building binary packages for release, but instead is (apparently) something enforced in the code in Git. IOW, it's not clear that "released version" means "tagged in Git" as opposed to "downloadable release from the web site".

[jefferai]

@ianlancetaylor I built Go from go1.5.1 tag with CGO_ENABLED=0 set (which appears to be the default anyways), and after setting that as GOROOT it still builds dynamic programs by default, unless I also set CGO_ENABLED=0 before building the program.

[ianlancetaylor]

I'm still not sure what you're referring to in #9344, but it doesn't much matter. What matters is the documentation.

Never set GOROOT. If it is in your environment, take it out. If you build a release, run bin/go from that release.

CGO_ENABLED=0 is not the default for a native build.

Setting CGO_ENABLED when building the Go sources is documented in src/make.bash.

[jefferai]

#9344 is the exact issue I've been having problems with. There are several mentions of released builds, for instance, #9344 (comment) and #9344 (comment)

It's not clear where CGO_ENABLED is toggled to 1 in a native build. Regardless, with CGO_ENABLED=0 exported and running all.bash, the built go binary is not static. This does work for my programs, though.

[ianlancetaylor]

The comments you link to from #9344 are both out of date, as it happens. In Go 1.5 the -a option to go build does rebuild everything, including the standard library, whether you are running a release build or not.

I just tried running

CGO_ENABLED=0 bash make.bash

on a clean checkout of Go tip. It built a statically linked program version of ../bin/go.

But, you are correct: when, using that version of go, I run go env CGO_ENABLED, it prints 1, and it will link packages like os/user dynamically. I did not expect that. I'm not sure whether it is a bug or not.

[jefferai]

OK -- I didn't realize the behavior changed again in 1.5.

I'll keep an eye on this report. Thanks for looking into it.

[rsc]

I am not 100% sure the requested behavior is what we want. I'm curious whether it changed or if it has always been the way it is now. I suspect the latter.

[rsc]

Looked some more. I think it has always been this way, at least back to Go 1.2: CGO_ENABLED controls now, not later. It does not bake in a default value during make.bash. Still not sure whether we want to change it.

[jefferai]

@rsc I appreciate you looking. As you can see from the initial issue I referenced (and others I can point to) usage of CGO_ENABLED vs. other methods of ensuring that a built binary is static (when not cross-compiling) has been a point of confusion, and I think a lot of that has been due to the changes to e.g. -a in 1.4 and more changes in 1.5.

Feel free to close this, unless you want to keep it open as a documentation enhancement request.

[rsc]

For now it's open because we may still want to change it.

[rsc]

I think this should probably force the default but it's too late for Go 1.6.

[bradfitz]

Didn't happen for 1.7 either.

[rsc]

OK, let's try this and see what breaks. Will send CL.

[gopherbot]

CL https://golang.org/cl/31141 mentions this issue.