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Kubernetes Hello World

Here is a sample Kubernetes manifest that deploys a web server for us:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:latest
          ports:
            - containerPort: 80

---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: ClusterIP

Let's create a file called test-app.yaml, save this content to it, and then run the following command.

kubectl apply -f test-app.yaml

Let's see check on our Kubernetes pod

kubectl get pods
Sample Output
NAME                              READY   STATUS    RESTARTS   AGE
nginx-deployment-96b9d695-ssw4m   1/1     Running   0          7s

Copy your pod name to another window. We will be using it for the next few commands...

Let's use the describe command to see interesting info about our pod.

kubectl describe pod your-pod-name-here
Sample Output
Name:             nginx-deployment-96b9d695-ssw4m
Namespace:        default
Priority:         0
Service Account:  default
Node:             minikube/192.168.49.2
Start Time:       Tue, 25 Feb 2025 13:25:04 +0000
Labels:           app=nginx
                  pod-template-hash=96b9d695
Annotations:      <none>
Status:           Running
IP:               10.244.0.5
IPs:
  IP:           10.244.0.5
Controlled By:  ReplicaSet/nginx-deployment-96b9d695
Containers:
  nginx:
    Container ID:   docker://9be8fd9f9105daedfa4fba6871431a57003d3860d5df23c6dd987d8900893cc1
    Image:          nginx:latest
    Image ID:       docker-pullable://nginx@sha256:9d6b58feebd2dbd3c56ab5853333d627cc6e281011cfd6050fa4bcf2072c9496
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Tue, 25 Feb 2025 13:25:06 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-wpwsx (ro)
Conditions:
  Type                        Status
  PodReadyToStartContainers   True 
  Initialized                 True 
  Ready                       True 
  ContainersReady             True 
  PodScheduled                True 
Volumes:
  kube-api-access-wpwsx:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  44s   default-scheduler  Successfully assigned default/nginx-deployment-96b9d695-ssw4m to minikube
  Normal  Pulling    43s   kubelet            Pulling image "nginx:latest"
  Normal  Pulled     43s   kubelet            Successfully pulled image "nginx:latest" in 225ms (225ms including waiting). Image size: 191998640 bytes.
  Normal  Created    43s   kubelet            Created container: nginx
  Normal  Started    42s   kubelet            Started container nginx

Finally, let's check our pod's logs to verify there are no errors/issues

kubectl logs your-pod-name
Sample Output
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Sourcing /docker-entrypoint.d/15-local-resolvers.envsh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2025/02/25 13:25:06 [notice] 1#1: using the "epoll" event method
2025/02/25 13:25:06 [notice] 1#1: nginx/1.27.4
2025/02/25 13:25:06 [notice] 1#1: built by gcc 12.2.0 (Debian 12.2.0-14) 
2025/02/25 13:25:06 [notice] 1#1: OS: Linux 6.8.0-1021-aws
2025/02/25 13:25:06 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2025/02/25 13:25:06 [notice] 1#1: start worker processes
2025/02/25 13:25:06 [notice] 1#1: start worker process 29
2025/02/25 13:25:06 [notice] 1#1: start worker process 30

Let's try accessing our web server

kubectl port-forward svc/nginx-service 8080:80 &

You should see output similar to the following:

Sample Output
Forwarding from 127.0.0.1:8080 -> 80
Forwarding from [::1]:8080 -> 80
curl localhost:8080
Sample Output
Handling connection for 8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

Now that we verified we can deploy a workload on Kubernetes, let's deploy our pipeline as a Kubernetes pod.