Pipelines: Caching between jobs/stages

Summary

When setting up GitLab CI Pipelines for a ruby project with a cache config for the vendor/ruby directory, in the next job/stage/etc the gems will be installed again instead of loaded from the cache. Same for every other directory (like node_modules).

Maybe I'm getting something wrong and you can help me to get the cache working.

Steps to reproduce

• Setup project
• Push some ruby project
• Create a .gitlab-ci.yml (content below)
• push
• See how the gems will be installed (Installting xyz instead of Using xyz) again for each job/stage/pipeline

Content of the .gitlab-ci.yml:

image: "ruby:2.4.0"

variables:
  RAILS_ENV: "test"
  GIT_DEPTH: "1"

cache:
  key: "ruby-240"
  paths:
  - vendor/ruby


before_script:
  - gem install bundler --no-ri --no-rdoc
  - RAILS_ENV=test bundle install --path vendor --without development

stages:
  - setup
  - check

setup:
  stage: setup
  script:
    - node -v
    - ruby -v
    - which ruby
    - which bundle
    - which bower

check:
  stage: check
  script:
    - echo 'works'

What is the current bug behavior?

The specified directories are not cached between stages/jobs/... despite the log says Creating cache ruby-240... at the end and Checking cache for ruby-240... as well as Successfully extracted cache at the beginning.

What is the expected correct behavior?

Bundler should say Using instead of Installing due the fact that the vendor/ruby dir is cached. This should work at least between stages/job but also between pipeline builds. Otherwise the setup process of our builds take forever (10 minutes +), which is not just annoying but also a bigger load for the GitLab.com pipeline workers.

Output of checks

This bug happens on GitLab.com