cmd/go: get with GIT_CONFIG ignores env variable

[valery-barysok]

What version of Go are you using (go version)?

$ go version go1.15.2 darwin/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN="/Users/user/work/sunnycat/bin"
GOCACHE="/Users/user/Library/Caches/go-build"
GOENV="/Users/user/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/user/go/pkg/mod"
GONOPROXY="github.com/user/*"
GONOSUMDB="github.com/user/*"
GOOS="darwin"
GOPATH="/Users/user/go"
GOPRIVATE="github.com/user/*"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.15.2/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.15.2/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/k9/h8z58c7n2wxf9gd6rm0m_bd40000gp/T/go-build919199640=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

export GIT_CONFIG=$(pwd)/.gitconfig
#[url "ssh://git@github.com"]
#	insteadOf = https://github.com

$ go get -u github.com/user/module

What did you expect to see?

go get takes into account GIT_CONFIG env variable

What did you see instead?

# cd .; git clone -- https://github.com/user/module /Users/user/go/src/github.com/user/module
Cloning into '/Users/user/go/src/github.com/user/module'...
fatal: could not read Username for 'https://github.com': terminal prompts disabled
package github.com/user/module: exit status 128

[cagedmantis]

Can you run git config --list --show-origin to ensure the configuration settings are as expected?

[valery-barysok]

@cagedmantis,
I run this command from different places and it works as expected. I see the configuration setting based on GIT_CONFIG value.
So git command works well but go get does not.

[valery-barysok]

@cagedmantis, Do you need additional info? It will be great feature for ability to work in multiple environments setup when use direnv or similar.

[valery-barysok]

I use direnv to manage environment variables depends on current directory and I think the issue arises when go changes directory under the hood while executes go get -u operation. And GIT_CONFIG value changes (clears). @cagedmantis , Could you confirm that there is directory changing during go get -u operation for some reason?

[cagedmantis]

@valery-barysok Thanks for the additional information. I am not able to reproduce this, even with some direnv experiments. I am going to loop in the maintainers of the go command for good measure.

/cc @bcmills @jayconrod @matloob

[bcmills]

@valery-barysok, go get does not change its own working directory, but it does invoke git in a different directory (namely, in the Go module cache).

The go command doesn't know anything about direnv or about the GIT_CONFIG environment variable, so if you're going that route it's on you to ensure that your GIT_CONFIG environment variable is set appropriately for commands executed in the module cache (and, for that matter, in temporary directories).

[bcmills]

@valery-barysok, can you confirm that your GIT_CONFIG setting applies to subdirectories of $(go env GOMODCACHE)?

[valery-barysok]

@bcmills, I can confirm that direnv also configured for go env GOMODCACHE in the same way as for dir where i execute go get. As expected it does not work but git clone works in both places. As I understand go get executes git clone and it should work as if i do the same by myself. But it looks like no env variables that provide correct setup of git when executes this command.

[valery-barysok]

@bcmills, I debugged go source code and seems like issue actually happens inside git itself when go executes git ls-remote -q origin while env and git config --list commands before git ls-remote -q origin provide correct values. It is succeed if I put .gitconfig file to user home directory instead of custom place for this operation.

I will continue to investigate.

[valery-barysok]

I resolved the issue by using XDG_CONFIG_HOME env variable instead of GIT_CONFIG.

So GIT_CONFIG is wrong way to provide custom place for git config file because it works with limited list of commands.
There is side effect when you use XDG_CONFIG_HOME because other applications respect this env variable and read/write their setting from this place.