I’m trying to build a GitLab server with build pipelines. I have already installed GitLab with Docker and created several runners. Now I want to connect the runners to the GitLab, but I keep getting the error message: tls: failed to verify certificate: x509: certificate relies on legacy Common Name field, use SANs instead

These are my steps to generate the certificates:

openssl genrsa -out ca.key 4096
openssl req -new -x509 -days 3650 -key ca.key -out ca.crt -subj "/C=DE/ST=BW/O=Example Company/CN=GitLab CA"
openssl genrsa -out server.key 4096
openssl req -new -key server.key -out server.csr -subj "/C=DE/ST=Baden-Wüttemberg/L=Mannheim/O=Example/OU=IT Dept/CN=gitlab.local" -addext "subjectAltName = DNS:localhost,DNS:gitlab.local"
openssl x509 -req -in server.csr -out server.crt -days 3650 -CA ca.crt -CAkey ca.key -CAcreateserial

My registration command : docker exec -it gitlab-runner-1 gitlab-runner register --url https://gitlab.local --token glrt-v8Cjr4ZaVQGKnnws7tAx --tls-ca-file /etc/gitlab-runner/ssl/ca.crt

I gave the server.crt and server.key files to the GitLab server and I made the ca.crt known to the GitLab runner.

Unfortunately, I still get the error even though I entered the domain name correctly with SAN. Does somebody has any idea? Thanks.

For completeness, here is my Docker Compose file:

version: '3.8'
services:
  gitlab:
    image: gitlab/gitlab-ee:latest
    container_name: gitlab
    restart: always
    hostname: 'gitlab.local'
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        external_url 'https://gitlab.example.de'
        gitlab_rails['gitlab_shell_ssh_port'] = 2222
    networks:
      - internal-services
      - gitlab-runner-network
    volumes:
      - '/docker-volumes/gitlab/config:/etc/gitlab'
      - '/docker-volumes/gitlab/logs:/var/log/gitlab'
      - '/docker-volumes/gitlab/data:/var/opt/gitlab'
    shm_size: '256m'
  gitlab-runner-1:
    image: gitlab/gitlab-runner:latest
    container_name: gitlab-runner-1
    hostname: gitlab-runner-1.local
    restart: always
    networks:
      - gitlab-runner-network
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /docker-volumes/gitlab-runner/config-1:/etc/gitlab-runner

networks:
  internal-services:
    external: true
  gitlab-runner-network:
    external: true

I tried these solution without success:
how to solve this errror “certificate relies on legacy Common Name field, use SANs instead” during gitlab runner registration?