Run (Docker) Test Container in gitlab with Maven - maven

Question

I am working in a gitlab ci/cd pipeline. This pipeline executes all of its commands (excluding the deployments) with maven and docker. In this case, I am trying to run integration tests (that are kicked off by maven), which use a test container (for the mysql database). These tests work fine when running locally. However, I am running into issues when I try to run them from gitlab. I am fairly certain my issue is I don't have access to docker (however, in this case, I need my image to have both docker and maven).
Here is the applicable section of gitlab file:
#This phase is only run when merging (to master)
merge_tests:
image: maven:latest
stage: mvn_build_and_test
#TODO can remove services if this does not work without docker image as base image
services:
- docker:stable-dind
#set variables for use later when running maven in script section
variables:
MAVEN_CLI_OPTS: "-s .m2/settings.xml --batch-mode"
MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository"
script:
#ONLY RUN WHEN MERGE REQUEST IS TO MASTER BRANCH
#if ["$CI_MERGE_REQUEST_TARGET_BRANCH_NAME" == "master"]; then
#check docker is installed and running
#- docker --version #this fails if uncommented
- mvn $MAVEN_CLI_OPTS clean install -Pintegration-test-profile
#; fi
#only:
#- merge_requests
Here is the error stack trace on gitlab:
org.testcontainers.containers.ContainerLaunchException: Container startup failed
1958 Caused by: org.testcontainers.containers.ContainerFetchException: Can't get Docker image: RemoteDockerImage(imageNameFuture=java.util.concurrent.CompletableFuture#21baa903[Completed normally], imagePullPolicy=DefaultPullPolicy(), dockerClient=LazyDockerClient.INSTANCE)
1959 Caused by: java.lang.IllegalStateException: Could not find a valid Docker environment. Please see logs and check configuration
Before anyone suggests it, this testing works locally (and has worked locally for a long time). Here is part of the sample output:
[INFO] --- maven-failsafe-plugin:2.22.1:integration-test (integration-tests) # reading-comprehension-api ---
[INFO]
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.connor.retrieving.GetByIsbnIT
-----content ommitted for brevity----------------------------
Tests run: 3, Failures: 0, Errors: 0, Skipped: 1, Time elapsed: 10.451 s - in com.connor.adding.AddAssessmentIT
--content ommitted, but test containers start
[INFO] --- maven-failsafe-plugin:2.22.1:verify (integration-tests) # reading-comprehension-api ---
[INFO]
[INFO] --- maven-cucumber-reporting:2.8.0:generate (addCucumberReport) # reading-comprehension-api ---
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
[INFO] About to generate Cucumber report.
[INFO]
[INFO] --- maven-cucumber-reporting:2.8.0:generate (getCucumberReport) # reading-comprehension-api ---
[INFO] About to generate Cucumber report.
[INFO]
[INFO] --- maven-cucumber-reporting:2.8.0:generate (updateCucumberReport) # reading-comprehension-api ---
[INFO] About to generate Cucumber report.
[INFO]
[INFO] --- maven-install-plugin:2.5.2:install (default-install) # reading-comprehension-api ---
[INFO] Installing /home/connor/Desktop/code/reading-comprehension-api/target/reading-comprehension-api-0.0.1-SNAPSHOT.jar to /home/connor/.m2/repository/com/connor/reading-comprehension-api/0.0.1-SNAPSHOT/reading-comprehension-api-0.0.1-SNAPSHOT.jar
[INFO] Installing /home/connor/Desktop/code/reading-comprehension-api/pom.xml to /home/connor/.m2/repository/com/connor/reading-comprehension-api/0.0.1-SNAPSHOT/reading-comprehension-api-0.0.1-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 38.282 s
[INFO] Finished at: 2019-12-04T22:31:23-05:00
How should i fix this? Should i create my own base image which has maven and docker installed? Can I easily modify my container to use apt get in my container? Any suggestions are welcome, but I would like to have both docker and maven, since they are in my technology stack and working--just a gitlab config issue.
Here is the project location on gitlab: https://gitlab.com/connorbutch/reading-comprehension-api
While i certainly welcome comments on other parts of the project, those should be directed to me via email,in order to keep this page clean (don't put them here)

Answer 1

For anyone who's wondering: You can fix this by adding a few variables to your CI/CD configuration.
The ones I added were:
MAVEN_CLI_OPTS: "-s .m2/settings.xml --batch-mode"
MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository"
#these were added to try and get test containers to work -- if it doesnt, can remove below two
DOCKER_HOST: "tcp://docker:2375"
DOCKER_DRIVER: "overlay2"

Answer 2

For anyone who's are running kubernetes runners the runner must be configured privileged to run dind service:
runners:
## Run all containers with the privileged flag enabled
## This will allow the docker:stable-dind image to run if you need to run Docker
## commands. Please read the docs before turning this on:
## ref: https://docs.gitlab.com/runner/executors/kubernetes.html#using-docker-dind
##
privileged: true
https://docs.gitlab.com/runner/install/kubernetes.html#running-privileged-containers-for-the-runners
Example from values.yaml