GitLab CI

In order to use Testcontainers in a Gitlab CI pipeline, you need to run the job as a Docker container (see Patterns for running inside Docker). So edit your .gitlab-ci.yml to include the Docker-In-Docker service (docker:dind) and set the DOCKER_HOST variable to tcp://docker:2375.

Here is a sample .gitlab-ci.yml that executes test with gradle:

# DinD service is required for Testcontainers
services:
  - docker:dind

variables:
  # Instruct Testcontainers to use the daemon of DinD.
  DOCKER_HOST: "tcp://docker:2375"
  # Improve performance with overlayfs.
  DOCKER_DRIVER: overlay2

test:
 image: gradle:5.0
 stage: test
 script: ./gradlew test