`jekyll build` has error but gitlab ci still continues

Question

I have a Jekyll website running on Gitlab Pages, and one of my pages contained an error. This error is found and reported by Jekyll, but the website is still deployed, just without that page.

In Gitlab's job output I see the following:

$ jekyll build -d public
...
Bundle complete! 5 Gemfile dependencies, 29 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-linux-musl]
Configuration file: /builds/TheOddler/mjb/_config.yml
            Source: /builds/TheOddler/mjb
       Destination: /builds/TheOddler/mjb/public
 Incremental build: disabled. Enable with --incremental
      Generating... 
             Error: YAML Exception reading /builds/TheOddler/mjb/_work/immaculate.md: (<unknown>): did not find expected key while parsing a block mapping at line 2 column 1
       Jekyll Feed: Generating feed for posts
                    done in 1.104 seconds.
 Auto-regeneration: disabled. Use --watch to enable.
Uploading artifacts for successful job 00:09
Uploading artifacts...

So it shows Error: YAML Exception ... but then still continues as if everything is OK.

The job in my .gitlab-ci.yml file looks like this:

build-jekyll:
  stage: build
  image: jekyll/jekyll:4.2.0
  script:
  - jekyll build -d public
  artifacts:
    paths:
    - public
  only:
  - master

Why does this happen? And is there a way to make the process fail, or at least report this as a warning so I know something went wrong?

Thanks!

Answer 1

This happens because Jekyll, dispite the error in the output, returns with exit code 0. You could try to add the --strict_front_matter option to let Jekyll return a non-zero exit code.