GitLab Advanced CI/CD - Hands-On Lab: Reviewing Best Practices

Estimate time to complete: 15 minutes

Objectives

• Reducing repetition in your pipeline
• Hidden jobs and map merges

In our testing pipeline, there are a few instances where we are repeating code and definitions. We already saw that it was possible to use caches to reduce repetition in the npm install of packages. In this lab, you will learn how to further reduce the repetition in your code.

Here is the current .gitlab-ci.yml file definition:

stages:
  - deps
  - test

workflow:
  auto_cancel:
    on_job_failure: all

default:
  image: node:latest

install deps:
  stage: deps
  script:
    - npm install jest-junit
  cache:
    key: node_mod
    paths:
      - node_modules
  
test binarysearch:
  before_script:
    - npm install -g jest
  script:
    - jest --ci --testResultsProcessor=jest-junit binarysearch.test.js
  cache:
    key: node_mod
    paths:
      - node_modules
test linearsearch:
  before_script:
    - npm install -g jest
  script:
    - jest --ci --testResultsProcessor=jest-junit linearsearch.test.js
  cache:
    key: node_mod
    paths:
      - node_modules

Task A. Simplifying your jobs

1. Navigate to your project repository.

2. Select the .gitlab-ci.yml file.

3. Select Edit > Edit in pipeline editor.

4. In our current .gitlab-ci.yml file, all of the tests contain the same set of artifacts. Instead of defining the artifacts at each job, you can instead first create a hidden job with the definition:

   .artifactdef: &artifactdef
     artifacts:
       when: always
       reports:
         junit: junit.xml
   

5. You can then use a map merge to add the artifact definition to all of your testing jobs:

   test binarysearch:
     script:
       - jest --ci --testResultsProcessor=jest-junit binarysearch.test.js
     <<: *artifactdef
     cache:
       key: $CI_COMMIT_REF_SLUG
       paths:
         - node_modules
   
   test linearsearch:
     script:
       - jest --ci --testResultsProcessor=jest-junit linearsearch.test.js
     <<: *artifactdef
     key: $CI_COMMIT_REF_SLUG
       paths:
         - node_modules
   

6. Additionally, we can move the cache into a hidden job to avoid repetition. In this example, we moved these definitions into the cachedef hidden job:

   stages:
     - deps
     - test
   
   workflow:
     auto_cancel:
       on_job_failure: all
   
   default:
     image: node:latest
   
   .artifactdef: &artifactdef
     artifacts:
       when: always
       reports:
         junit: junit.xml
   
   .cachedef: &cachedef
     cache:
       key: $CI_COMMIT_REF_SLUG
       paths:
         - node_modules
   
   install deps:
     stage: deps
     script:
       - npm install jest-junit
     cache:
       key: $CI_COMMIT_REF_SLUG
       paths:
         - node_modules
   
   test binarysearch:
     before_script:
       - npm install -g jest
     script:
       - jest --ci --testResultsProcessor=jest-junit binarysearch.test.js
     <<: [*artifactdef, *cachedef]
   
   test linearsearch:
     before_script:
       - npm install -g jest
     script:
       - jest --ci --testResultsProcessor=jest-junit linearsearch.test.js
     <<: [*artifactdef, *cachedef]
   

   This change not only reduces the total number of lines of code, but also makes it so if the artifact changes, you only need to change it in one place, rather than multiple locations.

7. After making these changes, select Commit changes.

8. Monitor your pipeline by selecting Build > Pipelines in the left sidebar.

9. After verifying that your pipeline ran successfully, return to your .gitlab-ci.yml file. Can you find any other optimizations for this file?

Lab Guide Complete

You have completed this lab exercise. You can view the other lab guides for this course.

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