gitlab ci cache/keep golang packages between stages - gitlab

Question

I use gitlab-ci to test, compile and deploy a small golang application but the problem is that the stages take longer than necessary because they have to fetch all of the dependencies every time.
How can I keep the golang dependencies between two stages (test and build)?
This is part of my current gitlab-ci config:
test:
stage: test
script:
# get dependencies
- go get github.com/foobar/...
- go get github.com/foobar2/...
# ...
- go tool vet -composites=false -shadow=true *.go
- go test -race $(go list ./... | grep -v /vendor/)
compile:
stage: build
script:
# getting the same dependencies again
- go get github.com/foobar/...
- go get github.com/foobar2/...
# ...
- go build -race -ldflags "-extldflags '-static'" -o foobar
artifacts:
paths:
- foobar

Answer 1

As mentioned by Yan Foto, you can only use paths that are within the project workspace. But you can move the $GOPATH to be inside your project, as suggested by extrawurst blog.
test:
image: golang:1.11
cache:
paths:
- .cache
script:
- mkdir -p .cache
- export GOPATH="$CI_PROJECT_DIR/.cache"
- make test

Answer 2

This is a pretty tricky task, as GitLab does not allow caching outside the project directory. A quick and dirty task would be to copy the contents of $GOPATH under some directory inside the project (say _GO), cache it and copy it upon each stage start back to $GOPATH:
after_script:
- cp -R $GOPATH ./_GO || :
before_script:
- cp -R _GO $GOPATH
cache:
untracked: true
key: "$CI_BUILD_REF_NAME"
paths:
- _GO/
WARNING: This is just a (rather ugly) workaround and I haven't tested it myself. It should only exhibit a possible solution.