list - How to merge YAML arrays?

Question

I would like to merge arrays in YAML, and load them via ruby -

some_stuff: &some_stuff
 - a
 - b
 - c

combined_stuff:
  <<: *some_stuff
  - d
  - e
  - f

I'd like to have the combined array as [a,b,c,d,e,f]

I receive the error: did not find expected key while parsing a block mapping

How do I merge arrays in YAML?

Answer 1

If the aim is to run a sequence of shell commands, you may be able to achieve this as follows:

# note: no dash before commands
some_stuff: &some_stuff |-
    a
    b
    c

combined_stuff:
  - *some_stuff
  - d
  - e
  - f

This is equivalent to:

some_stuff: "a
b
c"

combined_stuff:
  - "a
b
c"
  - d
  - e
  - f

I have been using this on my gitlab-ci.yml (to answer @rink.attendant.6 comment on the question).

---

Working example that we use to support requirements.txt having private repos from gitlab:

.pip_git: &pip_git
- git config --global url."https://gitlab-ci-token:${CI_JOB_TOKEN}@gitlab.com".insteadOf "ssh://git@gitlab.com"
- mkdir -p ~/.ssh
- chmod 700 ~/.ssh
- echo "$SSH_KNOWN_HOSTS" > ~/.ssh/known_hosts
- chmod 644 ~/.ssh/known_hosts

test:
    image: python:3.7.3
    stage: test
    script:
        - *pip_git
        - pip install -q -r requirements_test.txt
        - python -m unittest discover tests

use the same `*pip_git` on e.g. build image...

where requirements_test.txt contains e.g.

-e git+ssh://git@gitlab.com/example/example.git@v0.2.2#egg=example