CI Runner Healthcheck doesnt recognize open port

I've the following CI config on my local CE 11.11.3, Runner 11.11.2:

stages:
  - run_jobs

variables:
  MYSQL_DATABASE: your_db_name
  MYSQL_ROOT_PASSWORD: mysql

test_service:
  stage: run_jobs
  image: alpine:latest
  services:
    - mariadb
  script:
    - apk --no-cache add mysql-client
    - mysql --version
    - sleep 10
    - echo "SHOW tables;"| mysql -u root -p"$MYSQL_ROOT_PASSWORD" -h mariadb "${MYSQL_DATABASE}"

It should start a MariaDB service and just connects to it. But I got always this warning and the connect doesn't work. The same with mysql or other versions of MariaDB.

Running with gitlab-runner 11.11.2 (ac2a293c)
  on 3889d5e6a75e PyK5_zUy
Using Docker executor with image alpine:latest ...
Starting service mariadb:latest ...
Pulling docker image mariadb:latest ...
Using docker image sha256:f1e4084965e5ec0ad678aca1b1d790fec14f831864c1e63a34aaddf43b793232 for mariadb:latest ...
Waiting for services to be up and running...

*** WARNING: Service runner-PyK5_zUy-project-2-concurrent-0-mariadb-0 probably didn't start properly.

Health check error:
service "runner-PyK5_zUy-project-2-concurrent-0-mariadb-0-wait-for-service" timeout

Health check container logs:
....

2019-06-25T14:51:45.993759123Z 2019-06-25 14:51:45 0 [Note] mysqld: ready for connections.
2019-06-25T14:51:45.993761286Z Version: '10.4.6-MariaDB-1:10.4.6+maria~bionic'  socket: '/var/run/mysqld/mysqld.sock'  port: 0  mariadb.org binary distribution
...
$ mysql --version
mysql  Ver 15.1 Distrib 10.3.16-MariaDB, for Linux (x86_64) using readline 5.1
$ sleep 10
$ echo "SHOW tables;"| mysql -u root -p"$MYSQL_ROOT_PASSWORD" -h mariadb "${MYSQL_DATABASE}"
ERROR 2002 (HY000): Can't connect to MySQL server on 'mariadb' (115)
ERROR: Job failed: exit code 1

I read about how the health check works and I can see via docker ps on the machine a new docker instance of mariadb listining on 3306/tcp. So the service is ready - the log message says it to, everything works, but the Gitlab Runner neither recognizes the running and open MariaDB port.

#> docker ps
CONTAINER ID        IMAGE                         COMMAND                  CREATED             STATUS                PORTS                                              NAMES
c3b11fb5cb2d        1b0e92b652c1                  "gitlab-runner-helpe…"   28 seconds ago      Up 26 seconds                                                            runner-PyK5_zUy-project-2-concurrent-0-mariadb-0-wait-for-service
75852e70a264        f1e4084965e5                  "docker-entrypoint.s…"   29 seconds ago      Up 27 seconds         3306/tcp                                           runner-PyK5_zUy-project-2-concurrent-0-mariadb-0
bc995cde3491        gitlab/gitlab-runner:latest   "/usr/bin/dumb-init …"   16 minutes ago      Up 16 minutes                                                            gitlab-runner_runner_1

So, what is the problem? Logs are good, Services are running, but Healthcheck or the CI can reach it.