Gitlab CI variable before script with curl raises YAML syntax error

Question

I am defining a variable JWT, I will store in it a token which I will use later inside the code. I'm going to obtain it at the before_script step through a curl call.

The problem is that when I try to run the pipeline, it fails with the error:

Found errors in your .gitlab-ci.yml: Included file .gitlab-ci.yml does not have valid YAML syntax!

I have already read this Stack Overflow answer in order to properly interpolate USER and PASS environment variables.

This is my .gitlab-ci.yml file:

build-dist:
  environment:
    name: develop
  variables:
    JWT: ""
  stage: build
  image: node:16-alpine
  cache:
    key:
      files:
        - yarn.lock
    paths:
      - node_modules
      - .yarn
  before_script:
    - if [ -z "$USER" ] || [ -z "$PASS" ]; then exit 1; fi
    - apk add curl 
    - JWT=$(curl -s -X POST -H "Content-Type: application/json" -d '{"username": "'"$USER"'","password": "'"$PASS"'"}' "https://example.com/token")

  script: 
    - yarn install --pure-lockfile --cache-folder .yarn
    - yarn build

How should I correct the follow line inside my .gitlab-ci.yml in order to make it work?

- JWT=$(curl -s -X POST -H "Content-Type: application/json" -d '{"username": "'"$USER"'","password": "'"$PASS"'"}' "https://example.com/token")

Answer 1

First, a handy tip for such GitLab CI issues:

• assuming your have a GitLab repo on https://gitlab.com/user/project,
• you can browse the page https://gitlab.com/user/project/-/ci/lint
• then paste the contents of the offending .gitlab-ci.yml file, and click on "Validate" to get more feedback (typically, the error line number, etc.)

Regarding the YAML snippet at stake, the crux of the issue is the - JWT=$(…) line as you mentioned in the question, more precisely:

• from a YAML point of view, the string JWT=… is not explicitly quoted,
• and as this text contains a :,
• the YAML parser then sees it as a map, i.e., as if you had written:

  - username: "NAME"
    other_key: "val"
  

To solve this, it appears you'd just need to "quote" this sequence item with ' or " and thus write a line of the form - "JWT=…", then escape the quotes accordingly inside… but I'd rather suggest (to avoid ugly escapes!) to rely on the so-called block style of YAML → this leads to:

- |
  JWT=$(curl -s -X POST -H "Content-Type: application/json" -d '{"username": "'"$USER"'","password": "'"$PASS"'"}' "https://example.com/token")