Downloading a package from Gitlab package registry

Question

I have a gitlab-ci.yml file that creates a maven deployment and am trying to trigger another pipeline that takes the package from the registry and create a docker image

image: maven:latest

before_script:
  - mvn --version

stages:
  - build
  - trigger

build:
  stage: build
  script:
    - mvn package
    - mvn deploy 
  artifacts:
    paths:
      - target/*

trigger:
  stage: trigger
  trigger:
    project: my/other/project/repo
    branch: master

I'm having trouble finding out just how to get that package (or published artifacts) to the triggered pipeline. When using the container registry I just specify the image and gitlab pulls it down, not sure if I'm missing something obvious here but how do I actually use/download a package from gitlab?

I've tried to curl files in the package registry like this

curl --header "PRIVATE-TOKEN: my_token" "https://gitlab.com/api/v4/projects/00112233/packages/generic/io/my/package/0.0.1-SNAPSHOT/myfile.xml"

which throws the following error

{"error":"package_version is invalid"}

But when I curl GET on the package that is the package version

[
  {
    "id": 123456,
    "name": "io/my/package",
    "version": "0.0.1-SNAPSHOT",
    "package_type": "maven",
    "status": "default",
    "_links": {
      "web_path": "/my/web/path/-/packages/00112233",
      "delete_api_path": "https://gitlab.com/api/v4/projects/0123456/packages/00112233"
    },
    "created_at": "2022-01-11T23:59:28.626Z",
    "tags": [
      
    ]
  }
]

Is it possible to use or download the packages in gitlab in another pipeline triggered?

Additional code:

.gitlab-ci.yml

image: maven:latest

before_script:
  - mvn --version

variables:
  PARENT_JOB_ID: myteststring # This works
  # PARENT_JOB_ID: $CI_JOB_ID # This doesn't

stages:
  - build
  - trigger

build:
  stage: build
  script:
    - mvn package
    - mvn deploy 

trigger:
  stage: trigger
  trigger:
    include: my_ci.yml

my_ci.yml

image:
  name: docker:20

services:
  - docker:dind

stages:
  - test

test:
  stage: test
  script:
    - echo $JOB_ID # echos nothing if $CI_JOB_ID is $PARENT_JOB_ID, echos the string if it's something else

========================

Output from job when PARENT_JOB_ID is set to a random string

Executing "step_script" stage of the job script
00:00
Using docker image sha256:15a9bc7c6340df2ac9d6c8196ca1d905180ddf2ca8b29a8d98f5422e2e5ccf85 for docker:20 with digest docker@sha256:a729cce205a05b0b86dc8dca87823efaffc3f74979fe7dc86a707c2fbf631b61 ...
$ echo "Test string = $PARENT_JOB_ID"
Test string = myteststring

Output from job when PARENT_JOB_ID is set to CI_JOB_ID

Executing "step_script" stage of the job script
00:00
Using docker image sha256:15a9bc7c6340df2ac9d6c8196ca1d905180ddf2ca8b29a8d98f5422e2e5ccf85 for docker:20 with digest docker@sha256:a729cce205a05b0b86dc8dca87823efaffc3f74979fe7dc86a707c2fbf631b61 ...
$ echo "Test string = $PARENT_JOB_ID"
Test string =

Answer 1

Maybe you are using the wrong API for the situation. Since you store it in artifacts. https://docs.gitlab.com/ee/api/job_artifacts.html#get-job-artifacts

GET /projects/:id/jobs/:job_id/artifacts

Before we use the the artifact API we firstly need the id of the job, which contains the latest artifacts, from the parent pipeline. To get this firstly we will find the id of the last pipeline (https://docs.gitlab.com/ee/api/pipelines.html#list-project-pipelines)

GET /projects/:id/pipelines

Command:

PIPELINE_ID=$(curl -s --header "PRIVATE-TOKEN: <access_token>"  "https://gitlab.com/api/v4/projects/<project_id>/pipelines" | jq '.[0].id')

Next, we will use the pipeline id to fetch the job id by specifying the job name. In your case build .To achieve this we will use the Gitlab API https://docs.gitlab.com/ee/api/jobs.html#list-pipeline-jobs

GET /projects/:id/pipelines

Command:

PARENT_JOB_ID=$(curl -s --header "PRIVATE-TOKEN: <access_token>" "https://gitlab.com/api/v4/projects/<project_id>/pipelines/$PIPELINE_ID/jobs" | jq '.[] | select(.name=="build") | .id')

Combining all this with the artifacts API we get the following code for the child pipeline code, my_ci.yml in your case:

image:
  name: docker:20

services:
  - docker:dind

stages:
  - test

test:
  stage: test
  script:
    - apk add jq curl
    - |
      PIPELINE_ID=$(curl -s --header "PRIVATE-TOKEN: <access_token>"  "https://gitlab.com/api/v4/projects/<project_id>/pipelines" | jq '.[0].id')
      PARENT_JOB_ID=$(curl -s --header "PRIVATE-TOKEN: <access_token>" "https://gitlab.com/api/v4/projects/<project_id>/pipelines/$PIPELINE_ID/jobs" | jq '.[] | select(.name=="build") | .id')
      wget -U "Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.17 (KHTML,like Gecko) Ubuntu/11.04 Chromium/11.0.654.0 Chrome/11.0.654.0 Safari/534.17" --header "PRIVATE-TOKEN: <access_token>" "https://gitlab.com/api/v4/projects/<project_id>/jobs/$PARENT_JOB_ID/artifacts" -O artifacts.zip