Question

I have created a local Minikube cluster, then a deployment for a hello-world example. After it is active, a service is created at the same time.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
spec:
  selector:
    matchLabels:
      run: hello-world-example
  replicas: 2
  template:
    metadata:
      labels:
        run: hello-world-example
    spec:
      containers:
        - name: hello-world
          image: gcr.io/google-samples/hello-app:2.0 # Works
          ports:
            - containerPort: 8080
              protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: hello-app-service
spec:
  # type: NodePort
  type: LoadBalancer
  selector:
    app.kubernetes.io/name: hello-world
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 8080
    # nodePort: 31579

I apply the deployment and service with kubectl apply-f hello-app.yaml I end up with the following example services:

NAMESPACE	NAME	TARGET PORT	URL
default	hello-app-service	8080	http://IP:31813
default	kubernetes	No node port
kube-system	kube-dns	No node port

Note: My actual IP is not actually "IP"

When I curl the URL for the hello-app-service, I end up with this:

curl: (7) Failed to connect to IP port 31813 after 0 ms: Connection refused

However, when I expose the deployment service manually in CLI with kubectl expose deployment hello-world --type=LoadBalancer --port=8080

I get the following result:

NAMESPACE	NAME	TARGET PORT	URL
default	hello-app-service	8080	http://IP:31813
default	hello-world	8080	http://IP:32168
default	kubernetes	No node port
kube-system	kube-dns	No node port

And after I curl the URL for new service "hello-world", I end with the proper result:

Hello, world! Version: 2.0.0 Hostname: hello-world-5bb7fff796-fmwl8

Can somebody please explain to me what I am doing wrong with the service? Why is the CLI service working, while the .yaml file service is not working, despite using the same configuration. I have tested both with the same exact service settings as the CLI command (Using LoadBalancer type) and also with NodePort and setting the specific port.

Versions: OS: Ubuntu 22.04.2 LTS Docker version: 24.0.2 Kubectl version: Client Version: v1.27.2 Kustomize Version: v5.0.1 Server Version: v1.26.3 Minikube version: v1.30.1

Answer 1

I think the issue is the selector you re using for your service. This created the deployment and service in one-step for me:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
spec:
  selector:
    matchLabels:
      run: hello-world-example
  replicas: 2
  template:
    metadata:
      labels:
        run: hello-world-example
    spec:
      containers:
        - name: hello-world
          image: gcr.io/google-samples/hello-app:2.0 # Works
          ports:
            - containerPort: 8080
              protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: hello-app-service
spec:
  # type: NodePort
  type: LoadBalancer
  selector:
    run: hello-world-example
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 8080

If this doesn t work, at the expose step (the one that worked) use a dry-run to output the svc into a yaml file without actually creating the svc. Helps me troubleshoot

kubectl expose deployment hello-world --type=LoadBalancer --port=8080 --dry-run=client -o yaml > hello-app-service.yaml

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