Tell us about your experience with Docker Compose, OpenShift, GitLab CI.

Docker Compose was used for local development and testing of multi-container applications. It allows describing services, networks, and volumes in a single YAML file, enabling quick setup and teardown of environments.

OpenShift was employed for deploying and managing containerized applications in production. It utilized features like automatic scaling, configuration management, secrets management, and CI/CD integration.

GitLab CI was used for automating the build, test, and deployment of applications. Pipelines with different stages, such as build, test, deploy, were configured using runners. It integrated with Docker for image creation and with OpenShift for deployment.

An example of a simple .gitlab-ci.yml for build and deploy:

stages:
  - build
  - deploy

build_image:
  stage: build
  script:
    - docker build -t myapp:$CI_COMMIT_SHA .
  only:
    - master

deploy_to_openshift:
  stage: deploy
  script:
    - oc login --token=$OPENSHIFT_TOKEN --server=$OPENSHIFT_SERVER
    - oc project myproject
    - oc set image deployment/myapp myapp=myapp:$CI_COMMIT_SHA
  only:
    - master

This stack allows efficient management of the application lifecycle from development to production.