Cannot connecto to external database from inside kubernetes pod

Question

I am trying to connect my spring-boot api inside a kubernetes pod to an external database (a separate machine but within the local network), however when running, I get SQLNonTransientConnectionException, UknownHostException: mysql-svc, the api cannot connect to the database but whenever I ping the database address from inside the pod using kubectl exec -it, I can ping it successfully, anybody who has experienced the same error as mine?

here is my application.properties connection uri and kubernetes objects:

spring.datasource.url=jdbc:mysql://mysql-svc/test?autoReconnect=true

---
apiVersion: v1
kind: Service
metadata:
 name: mysql-svc
spec:
 type: ClusterIP
 ports:
 - port: 3306
   targetPort: 3306
---
apiVersion: v1
kind: Endpoints
metadata:
 name: mysql-svc
subsets:
 - addresses:
   - ip: 10.0.123.28
   ports:
   - port: 3306
     name: mysql-svc

score 2 · Answer 1 · answered Oct 04 '19 at 15:28

2

After hours of digging and reconfiguring, I finally get it to work, thanks to Xenwar from kubernetes group for pointing out the externalIP property, it turns out that i need to point my app to an external ip, in this case the database, here is the service object:

apiVersion: v1
kind: Service
metadata:
  name: db-con
spec:
  selector:
    app: api2
  ports:
    - name: http
      protocol: TCP
      port: 3306
      targetPort: 3306
  externalIPs:
    - 10.0.123.28

answered Oct 04 '19 at 15:28

Anthony

77
1
10

Did you change your EndPoints object? I kind of confuse since the services are different. Can you show me your full code? – Eko Andri Oct 05 '20 at 14:33
It worked for me as well, but I was not able to do it using endpoints. Confused. – Raam Mishra Jan 26 '21 at 15:19
can you please share your deployment yml? – Abdul Apr 28 '21 at 09:07

Burak Serdar · Answer 2 · 2019-10-02T16:34:04.717

0

You service is not a "headless" service. Set the IP to None:

spec:
  clusterIP: None
  ports:
   - port: 3306
     targetPort: 3306

https://kubernetes.io/docs/concepts/services-networking/service/#headless-services

edited Oct 02 '19 at 16:34

answered Oct 02 '19 at 16:02

Burak Serdar

46,455
3
40
59

im getting invalid value value: spec.clusterIP: Invalid value: "None": field is immutable – Anthony Oct 02 '19 at 16:10
Maybe it is not letting you change the IP once it is created. Try removing the service and re-creating it. – Burak Serdar Oct 02 '19 at 16:12
I already did, i removed the type entry as well but to no avail, I still can't access the database. – Anthony Oct 02 '19 at 16:20

score 0 · Answer 3 · answered Oct 03 '19 at 08:57

If I understand you correctly you need a ExternalName service type.

ExternalName: Maps the Service to the contents of the externalName field (e.g. foo.bar.example.com), by returning a CNAME record with its value. No proxying of any kind is set up.

Here is an example:

apiVersion: v1
kind: Service
metadata:
  name: my-service
  namespace: prod
spec:
  type: ExternalName
  externalName: my.database.example.com

When looking up the host my-service.prod.svc.cluster.local, the cluster DNS Service returns a CNAME record with the value my.database.example.com. Accessing my-service works in the same way as other Services but with the crucial difference that redirection happens at the DNS level rather than via proxying or forwarding.

Please let me know if that helped.

still getting this error: Caused by: java.net.UnknownHostException: mysql-svc, I was wondering if the problem is in my application.properties file.. — Anthony, Oct 03 '19 at 12:12
In that case please take a look [here](https://stackoverflow.com/questions/6484275/java-net-unknownhostexception-invalid-hostname-for-server-local) — Wytrzymały Wiktor, Oct 04 '19 at 12:02

Cannot connecto to external database from inside kubernetes pod

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