Gitlab's artifacts zip file is empty - docker

Question

I am trying to run the Robot Framework Tests in a Gitlab CI and download the generated report as an artifact. So far, I have succeeded running the tests in the pipeline and generate the artifact, but the generated zip is empty. What do I miss?
This is my Dockerfile:
FROM ppodgorsek/robot-framework:latest
COPY resources /opt/robotframework/resources
COPY tests /opt/robotframework/tests
COPY libs /opt/robotframework/libs
And this is my stage in the gitlab-ci.yml:
run robot tests dev:
variables:
# more variables
ROBOT_OPTIONS: "--variable ENV:dev -e FAIL -e PENDING"
allow_failure: true
services:
- name: docker:dind
stage: run-robot-tests
image: docker:latest
script:
- mkdir -p reports
# mode docker run commands
- docker -H $DOCKER_HOST run --rm --network localnet --env "ROBOT_OPTIONS=${ROBOT_OPTIONS}" -v reports:/opt/robotframework/reports --name robot $CONTAINER_DEV_IMAGE
artifacts:
name: ${CI_JOB_NAME}-${CI_COMMIT_REF_NAME}
paths:
- reports/
when: always
tags:
- d-i-d
only:
refs:
- dev
I have omitted some details that are specific to our project.
But just to give you an idea of our set-up, we are pulling the docker image ppodgorsek/robot-framework and we run with it the tests against another docker container that runs the front-end of our project. To make sure that all containers are on the same network we are using docker-in-docker. In the same network lives also our back-end container and our db.
This is the tail of my job's output.
==============================================================================
Tests | PASS |
3 critical tests, 3 passed, 0 failed
3 tests total, 3 passed, 0 failed
==============================================================================
Output: /opt/robotframework/reports/output.xml
Log: /opt/robotframework/reports/log.html
Report: /opt/robotframework/reports/report.html
Uploading artifacts...
reports/: found 1 matching files
Trying to load /builds/automation/system-tests.tmp/CI_SERVER_TLS_CA_FILE ...
Dialing: tcp gitlab.surfnet.nl:443 ...
Uploading artifacts to coordinator... ok id=42435 responseStatus=201 Created token=g8cWYYun
Job succeeded
You can see the console output from running the tests and then you can see where robot stores the generated output.
Next it shows that the artifact is generated, which it is, only problem is that is empty.

Answer 1

Ok, I was indeed very close. People from the Robot Framework community pointed me to the right direction! :D
The problem was in the command:
- docker -H $DOCKER_HOST run --rm --network localnet --env "ROBOT_OPTIONS=${ROBOT_OPTIONS}" -v reports:/opt/robotframework/reports --name robot $CONTAINER_DEV_IMAGE
and more specifically, on the relative path for the volume:
-v reports:/opt/robotframework/reports
Thus, the solution was using an absolute path:
-v $PWD/reports:/opt/robotframework/reports