Can I change gitlab-ci.yml file mid execution?

This is our simplified gitlab-ci.yml

stages: 
    - build
    - deploy

# fetch home repo that'll run the pipeline processes
before_script:
    - git clone [email protected]:home_repo/home_repo.git
    - cd home_repo

build:
  stage: build
  needs: []
  resource_group: $CI_PROJECT_NAME'_build'
  script:
    - ./pipeline.sh build

deploy_environment1:
  stage: deploy
  needs: [build]
  resource_group: deploy_environment1
  script:
    - ./pipeline.sh deploy env1

deploy_environment2:
  stage: deploy
  needs: [build]
  resource_group: deploy_environment2
  script:
    - ./pipeline.sh deploy env2

Adding 5-10 environments would blow up the size by a lot. How can we handle that?

Possible solution 1: Have one job that will create a list of all environments available and deploy to them. However, we won't have a good pipeline view of how each deployment went.

deploy_environments:
  stage: deploy
  needs: [build]
  resource_group: deploy_environments
  script:
    - ./pipeline.sh deploy to_all

Possible solution 2: before_script fetches a list of all environments and inserts as many deploy_environment job definitions as needed. But we don't know how to do that. Hence the question in the title.

Solution 1:

Can I change gitlab-ci.yml file mid execution?

No, not really. The closest thing to that would be using dynamic child pipelines where the YAML for a child pipeline is generated dynamically by another job in the parent pipeline.

That would allow you to achieve the effect you want.

Adding 5-10 environments would blow up the size by a lot. How can we handle that?

Alternative to (or even in combination with) using dynamic child pipelines, you could use a parallel matrix for concise definitions.

Something like this:

deploy:
  stage: deploy
  script:
    - ./pipeline.sh deploy $ENV_NAME
  parallel:
    matrix:
      - ENV_NAME: [env1, env2]