cmd/go: command to print out the directory Go will install binaries into

[kevinburke1]

Go can install binaries into one of several locations, I think:

• if GOBIN is set, go will install to that directory
• if GOPATH is set, go will install to GOPATH[0]/bin
• otherwise (usually), $HOME/go/bin

I'm working with several people who are not really Go programmers, but need to install Go services in order to do their jobs (frontend programming, design, etc). It's a frequent pattern to have instructions that say like "run go install ./... and then start the server" and then they get "meter-server: command not found" because they haven't added whatever directory to their $PATH. So then I need to figure out where Go is actually installing binaries to and then walk them through that process. This is more difficult now when I can't sit right next to them and walk through the commands.

Having a way to easily see which directory Go is installing, or going to, install packages would be very helpful.

Going beyond that, a tool in the x/tools that can append that directory to your $PATH, based on your shell, would be extremely helpful.

[seankhliao]

maybe we can make GOBIN point to the chosen directory if otherwise unset? Then the command would be go env GOBIN

cc @bcmills @jayconrod @matloob

[kevinburke1]

"go help environment" reports:

Additional information available from 'go env' but not read from the environment:

    GOEXE
	    The executable file name suffix (".exe" on Windows, "" on other systems).
    GOGCCFLAGS
	    A space-separated list of arguments supplied to the CC command.
    GOHOSTARCH
	    The architecture (GOARCH) of the Go toolchain binaries.
    GOHOSTOS
	    The operating system (GOOS) of the Go toolchain binaries.
    GOMOD
	    The absolute path to the go.mod of the main module.
	    If module-aware mode is enabled, but there is no go.mod, GOMOD will be
	    os.DevNull ("/dev/null" on Unix-like systems, "NUL" on Windows).
	    If module-aware mode is disabled, GOMOD will be the empty string.
    GOTOOLDIR
	    The directory where the go tools (compile, cover, doc, etc...) are installed.
    GOVERSION
	    The version of the installed Go tree, as reported by runtime.Version.

Perhaps we could add another value? GOINSTALLDIR or similar. One issue is GOINSTALLDIR would be less permanent than the values listed above.

[kevinburke1]

or "go tool installdir"

[bcmills]

Duplicate of #23439?

[bcmills]

Also note that you can use go list -f {{.Target}} $IMPORTPATH to obtain this information for a given package main.

[kevinburke1]

If you want "go env GOBIN" to always print the answer to this question instead of being empty if $GOBIN is empty, then yes it's a duplicate, however there are a few different ways to potentially solve this problem.

[kevinburke1]

Also note that you can use go list -f {{.Target}} $IMPORTPATH to obtain this information for a given package main.

This is really helpful and does basically what I want, thanks, though I guess the interface could be more intuitive. In the #general channel of the Gophers slack no one has suggested this so far in about 30 minutes, which suggests awareness of this solution is not widespread.

[eliasnaur]

I'm working with several people who are not really Go programmers, but need to install Go services in order to do their jobs (frontend programming, design, etc). It's a frequent pattern to have instructions that say like "run go install ./... and then start the server" and then they get "meter-server: command not found" because they haven't added whatever directory to their $PATH.

If you have go install ... in your instructions, why not have go run ... instead? With Go 1.17 you can even do go run domain.com/your/main/pkg@some-version outside of any module.

[kevinburke]

go list -f {{.Target}} $IMPORTPATH

Note this doesn't work to check if binaries are installed if they're not present in go.mod, for example test or build helpers like staticcheck.

[thockin]

I'd really appreciate the ability to do something like:

tool=$(go install --print-result example.com/tool)
"$tool" -flags

[hyangah]

We see three different use cases and are considering the following fixes.

1. A user ran go install but the installed binary is not in user's PATH. User doesn't know where it is installed.
   Possible fix: let go install print the location in stderr if it's installed in the path that's not in PATH.

2. A user wants to access the installation info programmatically post go install (e.g. cmd/go: command to print out the directory Go will install binaries into #45546 (comment))
   Possible fix: let go install -where print the location in stdout.

3. A user wants to know where the tool(s) would be installed without installing the tools.
   Possible fix: fix cmd/go: default GOBIN to GOPATH[0]/bin when outside of GOPATH? #23439 (go env GOBIN for module-aware mode)

   Alternatives are go mod init dummy && go get <path> && go list -f {{.Target}}, go install -n <path> &2>1 | grep 'mv $WORK' which aren't ideal.

[thockin]

I hit this again this week with a tool within Kubernetes which had not properly set GOPATH and things got splatted all over.

What I'd really love to see is a per-{repo, metadata, dir, something} metadata file which lets me set GOBIN, GOCACHE, GOMODCACHE, and other things (anything that defines where go will write files) to a known place. E.g.

$ cat go.defs
GOBIN = ./_output/bin
GOCACACE = ./_cache/build
GOMODCACHE = ./_cache/mod

[ianlancetaylor]

@thockin That sounds like the work module go.env file. Maybe? Should we try to figure out how to implement more specific versions of #57179?

[thockin]

Honestly, I forgot about that thread, where I made more or less the same request :) That one is closed, but yeah - a per-workspace or even per-directory go.env seems like it would do what I want.