I’ve a self hosted gitlab runner,
I want to run unit tests in runner and I’ve a database container dump in aws s3 that I want to use while running unit tests.
Locally unit-tests and same database setup is working.
so,

• I’m running runner with custom image with php, docker, awscli and other installed
• I’m using service docker:dind to have container where I can load my database image dump
• I downloaded & loaded the db docker image dump to service container
• I run the container
• But I get error as below while connecting to mysql

  [PDOException]                             
  SQLSTATE[HY000] [2002] Connection refused  

#sectet.yml (php symfony)
  database:
    main:
      dsn: "mysql:host=dev.dev;port=3308;dbname=******"
      username: "*****"
      password: "*********"
      driver_options:
        1002: "SET NAMES UTF8"

#.gitlab-ci.yml

default:
  image: $CI_REGISTRY/bitcoin/docker-php-builds/php-fpm-ubuntu:8.1

stages:
  - install
  - lint
  - build
  - test

variables:
  FF_NETWORK_PER_BUILD: true
  CI_DEBUG_SERVICES: "true"
  CI_DEBUG_TRACE: "true"
  MYSQL_USER: "gkrw" # not possible to configure in variable because of length < 8
  DOCKER_HOST: tcp://dev.dev:2375
  DOCKER_DRIVER: overlay2  #required for DinD to work in GitLab CI
  DOCKER_TLS_CERTDIR: ""

services:
  - name: docker:dind
    alias: dev.dev

cache: &global_cache
  key:
    files:
      - composer.lock
      - ${DB_BACKUP_FILE_NAME}
  policy: pull-push

install-dependencies:
  stage: install
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  before_script:
    - apt-get update -yqq && apt-get install -yqq make
    - make prepare-db
  script: make install-dependencies
  cache:
    <<: *global_cache
  artifacts:
    expire_in: 1d
    paths:
      - vendor

lint-md:
  stage: lint
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make lint-md
lint-php:
  stage: lint
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make lint-php

build-php:
  stage: build
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make build-php

test-db:
  stage: test
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make test-db
test-integration:
  stage: test
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make test-integration
test-i18nl10n:
  stage: test
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script: make test-i18nl10n
test-unit:
  stage: test
  rules:
    - if: $CI_COMMIT_BRANCH == "main" || $CI_PIPELINE_SOURCE == "merge_request_event"
  script:
    - make test-unit

Makefile
.PHONY: prepare-db install install-dependencies lint lint-md lint-php build build-php test test-db test-integration test-i18nl10n test-unit

#### download dump from S3 and restore it.
prepare-db:
    # Download database backup from S3
    aws s3 cp ${DB_BACKUP_BUCKET_URL}${DB_BACKUP_FILE_NAME} ./ --only-show-errors;
    # Login to Docker registry
    docker login ${CI_REGISTRY} -u ${DOCKER_REGISTRY_USER} -p ${DOCKER_REGISTRY_PWD}
    # Load the Docker image backup
    docker load -i $(DB_BACKUP_FILE_NAME)
    # Run container from the loaded image
    docker run -d --name=phpdev-db-snap -h "dev.dev" -p 3308:3306 --restart=always -m 8GB --oom-kill-disable IMAGE_NAME

#### install
install: install-dependencies

install-dependencies:
    #Install dependencies
    composer install --no-progress
    docker logs --since=2h phpdev-db-snap
    composer init-dev-environment # HERE IT'S FAILING AS I'M CONNECTING TO DATABASE TO MAKE OPERATION

#### lint
lint: lint-md lint-php

lint-md:
    @echo lint-md

lint-php:
    @echo lint-php

#### build
build: build-php

build-php:
    @echo build-php

#### test
test: test-db test-i18nl10n test-unit test-integration

test-db:
    @echo test-db

test-integration:
    @echo test-integration

test-i18nl10n:
    @echo test-i18nl10n

test-unit:
    @echo --------- Running unit-tests ---------
    vendor/phpunit/phpunit/phpunit
    @echo --------- unit-tests finished ---------

config.toml
concurrent = 1
check_interval = 0
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = "gitlab-runner"
  url = "https://*****.de"
  id = 6
  token = "****"
  token_obtained_at = 2023-12-13T10:20:05Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "docker"
  cache_dir = "/cache"
  [runners.docker]
    tls_verify = false
    image = "alpine:latest"
    privileged = true
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache","/certs"]
    shm_size = 0
    network_mtu = 0

[[runners]]
  name = "gitlab-runner"
  url = "https://******.de"
  id = 7
  token = "****"
  token_obtained_at = 2023-12-13T10:26:46Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "docker"
  cache_dir = "/cache"
  [runners.cache]
    MaxUploadedArchiveSize = 0
  [runners.docker]
    tls_verify = false
    image = "alpine:latest"
    privileged = true
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache","/certs"]
    shm_size = 0
    network_mtu = 0

Tried same code and image dump locally which is working fine.