The reference documentation when it comes to couple golang and continuous integration in Gitlab is this one, it’s well put, easy to read and pretty accurate. Except for the caching part, or at least nowadays with go modules. This is what happens when a commit is pushed with the .gitlab-ci.yml given as an example in that document:
131 Creating cache default... 132 WARNING: /apt-cache: no matching files 133 WARNING: /go/src/github.com: no matching files 134 WARNING: /go/src/gitlab.