如何在Kubernetes上访问MySQL即服务？

Question

I have the following deployment...

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-data-disk
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-deployment
  labels:
    app: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
        - name: mysql
          image: mysql:5.7
          ports:
            - containerPort: 3306
          volumeMounts:
            - mountPath: "/var/lib/mysql"
              subPath: "mysql"
              name: mysql-data
          env:
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-secrets
                  key: ROOT_PASSWORD
      volumes:
        - name: mysql-data
          persistentVolumeClaim:
            claimName: mysql-data-disk

This works great I can access the db like this...

kubectl exec -it mysql-deployment-<POD-ID> -- /bin/bash

Then I run...

mysql -u root -h localhost -p

And I can log into it. However, when I try to access it as a service by using the following yaml...

---
apiVersion: v1
kind: Service
metadata:
  name: mysql-service
spec:
  selector:
    app: mysql
  ports:
    - protocol: TCP
      port: 3306
      targetPort: 3306

I can see it by running this kubectl describe service mysql-service I get...

Name:              mysql-service
Namespace:         default
Labels:            <none>
Annotations:       kubectl.kubernetes.io/last-applied-configuration:
                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"mysql-service","namespace":"default"},"spec":{"ports":[{"port":33...
Selector:          app=mysql
Type:              ClusterIP
IP:                10.101.1.232
Port:              <unset>  3306/TCP
TargetPort:        3306/TCP
Endpoints:         172.17.0.4:3306
Session Affinity:  None
Events:            <none>

and I get the ip by running kubectl cluster-info

#kubectl cluster-info
Kubernetes master is running at https://192.168.99.100:8443
KubeDNS is running at https://192.168.99.100:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

but when I try to connect using Oracle SQL Developer like this...

It says it cannot connect.

How do I connect to the MySQL running on K8s?

Answer 1

Service type ClusterIP will not be accessible outside of Pod network. If you don't have LoadBalancer option, then you have to use either Service type NodePort or kubectl port-forward

Answer 2

1. You need your mysql service to be of Type NodePort instead of ClusterIP to access it outside Kubernetes.

2. Use the Node Port in your client config

Example Service:

apiVersion: v1
kind: Service
metadata:
  name: mysql-service
spec:
  type: NodePort
  selector:
    app: mysql
  ports:
    - protocol: TCP
      port: 3306
      nodePort: 30036
      targetPort: 3306

So then you can use the port: 30036 in your client.