Unable to pass variable to downstream pipeline on GitLab CI

Question

For over a week I've been fighting with passing a variables between jobs in multi-project pipeline in GitLab CI and got lots of weird errors. The mechanism looks like very basic and it drives me crazy that such an obvious thing still doesn't work for me, if somebody ran into similar issues - I would appreciate your help!

So what I've been trying to make: I have two projects on gitlab and I'm trying to link them in a single multi-project pipeline, the jobs schema looks like this: In project A:

variables: BUILD_PATH:""

build:
    script:
        - $BUILD_PATH="some-path" #the important point here that this value sets inside the job, it's not static

bridge:
  variables: 
    PATH: $BUILD_PATH
    RUN_TYPE: test #this value is a static and it passes correctly, no issues here
  trigger:
    project: project-B-path

In project B:

variables: 
  PATH: ""
  RUN_TYPE: ""

test:
  script: 
    echo "From upstream pipeline dynamic: $PATH"
    echo "From upstream pipeline static: $RUN_TYPE"
    ...

When I run it on CI I have the $RUN_TYPE variable correctly passed and empty value in $PATH variable (even though, $BUILD_PATH has the correct value during run of the build job). Tried many approaches - to set the $BUILD_PATH value in before script, to pass environment value (like CI_JOB_ID) to job in project B, to not create this variable at all in project B, etc. Nothing helped, dynamic variable always has empty value.

Then I've tried to save the dynamic var $BUILD_PATH in .env file and to publish it as artefact, so the bridge job could read it from there. I did it like that:

build:
    script:
    - some code here
    - echo "BUILD_VERSION=hello" >> vars.env
  artifacts:
    reports:
      dotenv: vars.env

When I run it on CI job always fails with errors like :

Uploading artifacts...
825vars.env: found 1 matching files and directories   
826WARNING: Failed to load system CertPool: crypto/x509: system root pool is not available on Windows 
827WARNING: Uploading artifacts as "dotenv" to coordinator... failed  id=1877748 responseStatus=500 Internal Server Error status=500 token=some-token-here
828WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
829WARNING: Uploading artifacts as "dotenv" to coordinator... failed  id=1877748 responseStatus=500 Internal Server Error status=500 token=some-token-here
830WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
831WARNING: Uploading artifacts as "dotenv" to coordinator... failed  id=1877748 responseStatus=500 Internal Server Error status=500 token=some-token-here
832FATAL: invalid argument  

I've also tried uploading .env file without name as I saw somewhere, like

 - echo "BUILD_VERSION=hello" >> .env

but again no luck, same 500 error. I keep researching this error, but so far - it's with me.

So the point - none of the ways of passing variables to the downstream pipeline in multi-project pipeline worked for me. If anyone met same issues or made it work in a different ways - please help

UPDATE: Resolved this issue in a different way - with cUrl trigger from project A like:

    - curl --request POST --form "token=$CI_JOB_TOKEN" --form ref=branchName --form "variables[PATH]=$BUILD_PATH" "https://gitlab.rim.net/api/v4/projects/projectID/trigger/pipeline"

Answer 1

Your downstream project job needs to declare needs: on the upstream project job.

upstream project:

build_vars:
  stage: build
  script:
    - echo "BUILD_VERSION=hello" >> build.env
  artifacts:
    reports:
      dotenv: build.env

deploy:
  stage: deploy
  trigger: my/downstream_project

downstream project:

test:
  stage: test
  script:
    - echo $BUILD_VERSION
  needs:
    - project: my/upstream_project
      job: build_vars
      ref: main
      artifacts: true

Answer 2

could you try the answer shared by @sytech, but ensure that you have "Maintainer" access for all the projects (both downstream and upstream).