How to use cache for a rails project in Gitlab CI?

Question

I've been trying to leverage Gitlab Ci's cache for my ruby on rails application but so far haven't had any luck, my application is using shared runners, maybe that's the issue?

Here are the contents of my .gitlab-ci.yml

services:
  - postgres:latest

rspec:
  stage: test
  script:
    - apt-get update -qy
    - apt-get install -y nodejs
    - gem install bundler
    - bundle check --path vendor/bundle || bundle install --path vendor/bundle --jobs $(nproc)
    - cp config/database.gitlab-ci.yml config/database.yml
    - RAILS_ENV=test bundle exec rake db:create db:schema:load
    - bundle exec rspec
  cache:
    paths:
      - vendor/bundle
  tags:
    - ruby
    - postgres

When my tests run I do see the runner checking for cached content, but it never restores it:

gitlab-ci-multi-runner 1.1.3 (a470667)
Using Docker executor with image ruby:2.1 ...
Pulling docker image postgres:latest ...
Starting service postgres:latest ...
Waiting for services to be up and running...
Pulling docker image ruby:2.1 ...

Running on runner-8a2f473d-project-1129003-concurrent-0 via runner-8a2f473d-machine-1462982763-a9a70bd7-digital-ocean-4gb...
Cloning repository...
Cloning into '/builds/foo/bar'...
Checking out 30ea1b5f as master...
Note: checking out '30ea1b5f036808f7e27bfa32e939c1f591343ba6'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b <new-branch-name>

HEAD is now at 30ea1b5... Fix width of tables contained in table-scroll divs
Checking cache for rspec/master...

$ apt-get update -qy

And when the build is about to finish I do see it trying to create the cache:

Creating cache rspec/master...
vendor/bundle: found 8917 matching files

Any ideas?

Answer 1

Gitlab Runner creates cache in git working directory by default. As you mentioned, your cache is created correctly, but it is stored in current git working directory of gitlab-runner. Whenever next build is run, gitlab-runner cleans the working directory (probably using git clean -dfx), which removes cache directory in git working directory.

You need to specify a separate cache directory for gitlab-runner. You can specify manually in /etc/gitlab-runner/config.toml file in the [[runners]] section using cache_dir setting key. Gitlab CI advanced configuration

You can also specify cache directory during gitlab runner registration using the --cache-dir option as in

gitlab-runner register --name blabblah --cache-dir /var/opt/gitlab/gitlab-runner-cache

Hope this helps

Answer 2

The cache actually started working properly a few weeks after I posted this question, no changes to my configuration were required. I believe it had to do with an update gitlab rolled out.