I have a gitlab pipeline where I build 2 projects.

Frist project:

buildcore:
  stage: core
  tags:
    - docker
  image: maven:3.8.6-eclipse-temurin-17-focal
  before_script:
    - cat ${SSH_BITBUCKET_KEY} | base64 -d > ${SSH_BITBUCKET_KEY}.tmp && mv ${SSH_BITBUCKET_KEY}.tmp
      ${SSH_BITBUCKET_KEY} && chmod 600 ${SSH_BITBUCKET_KEY}
    - git clone ssh://git@git:7999/ingo/core.git
  script:
    - ls -la
    - cd core
    - MAVEN_OPTS="-Xrs -Xmx1024m -Xss1m" mvn install -Pbuild 
      -Dmaven.repo.local=mvn.repo 
      -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn 
      -s ${CI_PROJECT_DIR}/.gitlab/settings.xml
    - echo "Ende!" 
    - ls -la
    - cd mvn.repo
    - ls -la
  artifacts:
      paths:
      - ${CI_PROJECT_DIR}/core/mvn.repo/**/*
      expire_in: 3 day

Works fine, everything was build and artifacts uploaded.
Next I try to build a second project with the artifacts from core.

buildapp:
  stage: app
  #when: manual  
  tags:
    - docker
  image: maven:3.8.6-eclipse-temurin-17-focal
  before_script:
    - cat ${SSH_BITBUCKET_KEY} | base64 -d > ${SSH_BITBUCKET_KEY}.tmp && mv ${SSH_BITBUCKET_KEY}.tmp
      ${SSH_BITBUCKET_KEY} && chmod 600 ${SSH_BITBUCKET_KEY}
    - git clone ssh://git@git:7999/ingo/myapp.git
  script:
    - cd myapp/myapp
    - MAVEN_OPTS="-Xrs -Xmx1024m -Xss1m" mvn install -P build 
      -Dmaven.repo.local=../../core/mvn.repo
      -s ${CI_PROJECT_DIR}/.gitlab/settings.xml
    - echo "Ende!" 

The artifacts from core build were added the correct way. So I have:

${CI_PROJECT_DIR}/core/mvn.repo
${CI_PROJECT_DIR}/myapp/myapp

I set the repo to the core/mvn.repo
But maven reports that the artifacst cannot be found.

[ERROR] Failed to execute goal on project xxx.myappexecutor: Could not resolve dependencies for project com.ingo:xxx.myappexecutor:jar:0.0.1-SNAPSHOT: The following artifacts could not be resolved: com.ingo:xxx.myapp.app:jar:2.8.0-SNAPSHOT, com.ingo:ct.myapp:jar:2.8.0-SNAPSHOT....and so forth

All dependencies are inside the “${CI_PROJECT_DIR}/core/mvn.repo” but it seems Maven cannot find them.
I trieds also with a full path in repo:

-Dmaven.repo.local=${CI_PROJECT_DIR}/core/mvn.repo

But no effect. Any hint what I do wrong?