Set GOCACHE and fix perms to avoid permissions errors

[crazy-max]

On some CI environments like Jenkins, cache could not be used due to permission errors. Here is a simple POC with a pipeline stage :

stage("Test") {
  docker.image('golang:1.11.5').inside {
    sh '''
    go version
    go mod download
    go get -u github.com/jstemmer/go-junit-report
    go get -u github.com/t-yuki/gocover-cobertura
    go test -coverprofile=bin/coverage.out -v ./...
    go test -json ./... > bin/report.json
    go test -v ./... 2>&1 | go-junit-report > bin/junit.xml
    gocover-cobertura < bin/coverage.out > bin/cobertura.xml
    '''
  }
}

This stage leads to :

[Pipeline] sh
+ go version
go version go1.11.5 linux/amd64
+ go mod download
go: disabling cache (/.cache/go-build) due to initialization failure: mkdir /.cache: permission denied
go: cannot use modules with build cache disabled
[Pipeline] }
$ docker top b511f686685e39732d3aad9486a66380632397aafe1ca3bf6eb2ce918e0aeba3 -eo pid,comm
$ docker stop --time=1 b511f686685e39732d3aad9486a66380632397aafe1ca3bf6eb2ce918e0aeba3
$ docker rm -f b511f686685e39732d3aad9486a66380632397aafe1ca3bf6eb2ce918e0aeba3

My current workaround sets GOCACHE to /tmp :

stage("Test") {
  docker.image('golang:1.11.5').inside('-e "GOCACHE=/tmp"') { c ->
    sh '''
    go version
    go mod download
    go get -u github.com/jstemmer/go-junit-report
    go get -u github.com/t-yuki/gocover-cobertura
    go test -coverprofile=bin/coverage.out -v ./...
    go test -json ./... > bin/report.json
    go test -v ./... 2>&1 | go-junit-report > bin/junit.xml
    gocover-cobertura < bin/coverage.out > bin/cobertura.xml
    '''
  }
}

[tianon]

Hmm, I hesitate to set a default here because it could mess up users, especially if they're already relying on the default of it being based on the value of $HOME (which would change depending on what user they run or build the image as).

[crazy-max]

@tianon Maybe we can rely on go env to take the default value ?

$ env

HOSTNAME=128fa8ec9532
HOME=/root
TERM=xterm
PATH=/go/bin:/usr/local/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
GOPATH=/go
PWD=/go
GOLANG_VERSION=1.11.5

$ go env

GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build206706691=/tmp/go-build -gno-record-gcc-switches"

[tao12345666333]

Hmm, I hesitate to set a default here because it could mess up users, especially if they're already relying on the default of it being based on the value of $HOME (which would change depending on what user they run or build the image as).

+1 👍

I don't think we should add default values to the base image.Users can set it up as needed.

xref: golang/go#29267
golang/go#29267 (comment)