Integrating External Services: Connect to Docker MariaDB from Pod running on Minishift - docker

Question

On a local development environment (Ubuntu) Docker and Minishift are installed.
With Docker a container with mariadb:10.3.11 is started:
docker run -e MYSQL_ROOT_PASSWORD=root -p 3306:3306 --name mariadb 4f2e75647d2a
Running curl from the host system has the following output:
curl 172.17.0.1:3306
curl: (56) Recv failure: Connection reset by peer
5.5.5-10.3.11-MariaDB-1:10.3.11+maria~bionic
QpatFAPM���rv{(RC:7G#H+mysql_native_password!��#08S01Got packets out of order%
The target is to connect to this MariaDB from a pod running in Minishift. I followed this tutorial: https://docs.okd.io/latest/dev_guide/integrating_external_services.html
apiVersion: v1
kind: List
items:
- kind: "Service"
apiVersion: "v1"
metadata:
name: "external-mysql-service"
spec:
ports:
- name: "mysql"
protocol: "TCP"
port: 3306
targetPort: 3306
nodePort: 0
selector: {}
- kind: "Endpoints"
apiVersion: "v1"
metadata:
name: "external-mysql-service"
subsets:
- addresses:
- ip: "172.17.0.1"
ports:
- port: 3306
name: "mysql"
However, the pod cannot connect to the MariaDB with the following error:
2019-02-19 18:00:42 [ERROR] HikariPool:567 - HikariPool-1 - Exception during pool initialization.
java.sql.SQLNonTransientConnectionException: Could not connect to address=(host=external-mysql-service)(port=3306)(type=master) : Connection refused (Connection refused)
If I connect to the pod via the terminal tab in the OpenShift Web Console and try
$ curl -v external-mysql-service:3306
* Rebuilt URL to: external-mysql-service:3306/
* Trying 172.30.23.62...
* TCP_NODELAY set
* connect to 172.30.23.62 port 3306 failed: Connection refused
* Failed to connect to external-mysql-service port 3306: Connection refused
* Closing connection 0
curl: (7) Failed to connect to external-mysql-service port 3306: Connection refused
How can I establish a connection from the Minishift pod to the Docker container?
The overall goal is to use arbitrary external services.

Answer 1

The IP of the Endpoint has to be the IP of the host system from the perspective of the vm-driver used with Minishift.
In my case the vm-driver is VirtualBox and the IP to access the host system is 10.0.2.2:
https://github.com/kubernetes/minikube/issues/352#issuecomment-237615642
Changing the IP of the endpoint worked for me:
- kind: "Endpoints"
apiVersion: "v1"
metadata:
name: "external-mysql-service"
subsets:
- addresses:
- ip: "10.0.2.2"
ports:
- port: 3306
name: "mysql"
Now the pod inside MiniShift can access the MariaDB running with docker on the host.