Continuous integration: From Jenkins to GitLab using Docker

This post details the migration of a Jenkins CI job to GitLab CI. It highlights the challenges of configuring external services like MongoDB in Jenkins and contrasts it with the simplified approach in GitLab CI using Docker services. The post provides the Jenkins job configuration, the corresponding `.gitlab-ci.yml` file, and the Dockerfile for a custom PHP dependency image. It also explains how to run GitLab jobs locally using GitLab Runner.