Connect to local database from inside minikube cluster

Question

I'm trying to access a MySQL database hosted inside a docker container on localhost from inside a minikube pod with little success. I tried the solution described Minikube expose MySQL running on localhost as service but to no effect. I have modelled my solution on the service we use on AWS but it does not appear to work with minikube. My service reads as follows

apiVersion: v1

kind: Service

metadata: 

  name: mysql-db-svc

  namespace: external

spec: 
  type: ExternalName
  ExternalName: 172.17.0.2

...where I try to connect to my database from inside a pod using "mysql-db-svc" on port 3306 but to no avail. If I try and CURL the address "mysql-db-svc" from inside a pod it cannot resolve the host name.

Can anybody please advise a frustrated novice?

Answer 1

This is because your service type is ExternalName which only fits in cloud environment such as AWS and GKE. To run your service locally change the service type to NodePort which will assign a static NodePort between 30000-32767. If you need to assign a static port on your own so that minikube won't pick a random port for you define that in your service definition under ports section like this nodePort: 32002.

And also I don't see any selector that points to your MySQL deployment in your service definition. So include the corresponding selector key pair (e.g. app: mysql-server) in your service definition under spec section. That selector should match with the selector you have defined in MySQL deployment definition.

So your service definition should be like this:

kind: Service
apiVersion: v1
metadata:
  name: mysql-db-svc
  namespace: external
spec:
  selector:
    app: mysql-server
  ports:
  - protocol: TCP
    port: 3306
    targetPort: 3306
    nodePort: 32002
  type: NodePort

After you deploy the service you can hit the MySQL service via http://{minikube ip}:32002 Replace {minikube ip} with actual minikube ip.

Or else you can get the access URL for the service with following command

minikube service <SERVICE_NAME> --url

Replace the with actual name of the service. In your case it is mysql-db-svc

Answer 2

If I'm not mistaken, you should also create an Endpoint for this service as it's external.

In your case, the Endpoints definition should be as follows:

kind: "Endpoints"
apiVersion: "v1"
metadata:
  name: mysql-db-svc
  namespace: external
subsets: 
- addresses:
  - ip: "10.10.1.1"
  ports:
    port: 3306

You can read about the external sources on Kubernetes Defining a service docs.

Answer 3

I'm using ubuntu with Minikube and my database runs outside of minikube inside a docker container and can be accessed from localhost @ 172.17.0.2. My Kubernetes service for my external mysql container reads as follows:

kind: Service
apiVersion: v1
metadata:
  name: mysql-db-svc
  namespace: external
spec: 
  type: ExternalName
  externalName: 10.0.2.2

Then inside my .env for a project my DB_HOST is defined as

mysql-db-svc.external.svc

... the name of the service "mysql-db-svc" followed by its namespace "external" with "svc"

Hope that makes sense.