stages:          # List of stages for jobs, and their order of execution
  - build
  - test
  - deploy
build-job:       # This job runs in the build stage, which runs first.
  stage: build
  script:
    - echo "Compiling the code..."
    - echo "Compile complete."
unit-test-job:   # This job runs in the test stage.
  stage: test    # It only starts when the job in the build stage completes successfully.
  script:
    - echo "Running unit tests... This will take about 60 seconds."
    - sleep 60
    - echo "Code coverage is 90%"
lint-test-job:   # This job also runs in the test stage.
  stage: test    # It can run at the same time as unit-test-job (in parallel).
  script:
    - echo "Linting code... This will take about 10 seconds."
    - sleep 10
    - echo "No lint issues found."
deploy-job:      # This job runs in the deploy stage.
  stage: deploy  # It only runs when *both* jobs in the test stage complete successfully.
  script:
    - echo "Deploying application..."
    - echo "Application successfully deployed."

git init
git add .
git commit -m "add a new python demo"
git remote add origin root@gitlab.example.com:8081/root/flask_web1.git
git push

docker run -d --name gitlab-runner --restart always --net=host \
     -v /srv/gitlab-runner/config:/etc/gitlab-runner \
     -v /var/run/docker.sock:/var/run/docker.sock \
     gitlab/gitlab-runner:latest

$ docker run --rm --net=host -it -v /srv/gitlab-runner/config:/etc/gitlab-runner gitlab/gitlab-runner:alpine-v14.4.2 register
Runtime platform                                    arch=amd64 os=linux pid=7 revision=50fc80a6 version=14.4.2
Running in system-mode.                            
Enter the GitLab instance URL (for example, https://gitlab.com/):
http://gitlab.example.com:8081
Enter the registration token:
8BxfhdBE2zf8NioR1UFE
Enter a description for the runner:
[yourdomain.com]: flask_demo
Enter tags for the runner (comma-separated):
python
Registering runner... succeeded                     runner=8BxfhdBE
Enter an executor: custom, parallels, docker+machine, kubernetes, docker, docker-ssh, shell, ssh, virtualbox, docker-ssh+machine:
shell
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded! 

$ cat /srv/gitlab-runner/config/config.toml 
concurrent = 1
check_interval = 0
[session_server]
  session_timeout = 1800
[[runners]]
  name = "demo"
  url = "http://gitlab.example.com:8081/"
  token = "PF41kT9ZV_1DoT6VzcCu"
  executor = "docker"
  [runners.custom_build_dir]
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]
    [runners.cache.azure]
  [runners.docker]
    tls_verify = false
    image = "ubuntu:20.04"
    dns = ["8.8.8.8", "1.1.1.1"]
    privileged = false
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache"]
    extra_hosts = ["gitlab.example.com:192.168.211.70"]
    shm_size = 0
..........
[[runners]]
  name = "flask_demo"
  url = "http://gitlab.example.com:8081"
  token = "tvCxfurs7EmRApH7un2a"
  executor = "shell"
  [runners.custom_build_dir]
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]
    [runners.cache.azure]

stages:
  - dep          # List of stages for jobs, and their order of execution
  - deploy
dep-job:
  stage: dep
  script:
    - apt -y install python3-pip
    - pip3 install flask
deploy-job:      # This job runs in the deploy stage.
  stage: deploy  # It only runs when *both* jobs in the test stage complete successfully.
  script:
    - echo "Deploying python flask demo application..."
    - python3 app.py"