Using go Dependencies from private repositories

Building Docker images (using Gitlab CI)

There some tutorials out there how to retrieve prviate dependencies for use in docker files like this Blog Post by Jeff Wenzbauer.

But all those I have seen require additional credentials to be created, maintained and injected. This makes using them either insecure or very cumbersome.

It think there is a simpler way by preparing a vendor directory and copying that into the builder image. The benefits are a simpler setup and the extra size of the builder image gets thrown away at the last step of the multi-step build process.

First prepare a cache containing all dependencies by adding the following two jobs to your .gitlab-ci.yml

go-deps:
  image: golang:latest
  variables:
    GOPATH: $CI_PROJECT_DIR/.go
  before_script:
    - mkdir -p .go
    - export GOPRIVATE=${CI_SERVER_HOST}
    - git config --global url.https://gitlab-ci-token:${CI_JOB_TOKEN}@${CI_SERVER_HOST}.insteadOf https://${CI_SERVER_HOST}
    - make mod
    - go mod vendor
  cache:
    paths:
      - .go/pkg/mod/
	  - vendor

docker-imager:
  image: docker-dind
  stage: deliver
  script:
    - COMMIT=$(git rev-parse --short HEAD)
    - docker build --file build/package/Dockerfile --tag $VERSION --arg VERSION=$VERSION --arg GO_MODULE=$GO_MODULE --arg COMMIT=$COMMIT 2>error.log
  dependencies:
    - lint:golang
    - test
  cache:
    paths:
      - .go/pkg/mod/
      - vendor
  artifacts:
    paths:
      - error.log
    when: on_failure