script represents the core steps performed by a job
script is just a YAML string
GitLab also supported YAML herestrings :
job_name:
script: |
pwd
whoami
printenv
Some jobs require preparation and cleanup to work correctly
job_name:
before_script: echo before_script
script: echo core
after_script: echo after_script
after_script runs even if the job failed (useful for cleanup)
See chapter Scriptblocks