Example: Create Pod with Run Command #
# Create a pod with Nginx container
kubectl run example-pod --image=nginx:alpine
# List pods
kubectl get pods
# List pod details
kubectl describe pod example-pod
# List pod details: Save output in YAML format into file
kubectl get pod example-pod -o yaml > example-pod.yaml
# Delete the pod
kubectl delete pod example-pod
Example: Create Pod with YAML Configuration #
Create Configuration #
# Create a pod configuration with dry-run
kubectl run nginx --image=nginx --dry-run=client -o yaml > example-pod.yaml
# Adopt the pod configuration and add a port
vi example-pod.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
containers:
- image: nginx
name: nginx
ports: # Add the port
- containerPort: 80
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
# Create the pod
kubectl create -f example-pod.yaml
Port-Forwarding #
# Create a port-forwarding
kubectl port-forward pod/nginx 8080:80
# Curl the Nginx container (in a new shell)
curl localhost:8080
# Shell output:
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
Example: Multi Container Pod #
Overview #
-
The following Pod configuration deploys a Nginx and an Alpine container within the same pod.
-
The Nginx container serves the default content on port “80” and the Alpine container is configured to curl the Nginx service at localhost port “80” every three seconds.
-
Containers within the same pod share the same network space and can communicate via
localhost, which refers to other containers in the same pod. -
All containers in the pod share the same IP address and each must ensure they use different port numbers if they serve network traffic.
Create Pod #
# Create a configuration for the pod
vi nginx-alpine-pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-alpine-pod
spec:
containers:
- name: nginx-container
image: nginx
ports:
- containerPort: 80
- name: alpine-container
image: alpine
command: ["/bin/ash", "-c"]
args:
- apk add --no-cache curl &&
while true; do
curl http://localhost:80/;
sleep 3;
done
"/bin/ash", "-c"Path to ash shell, the “-c” option tells the shell to take the next string as a command to execute.
# Create the pod
kubectl create -f nginx-alpine-pod.yaml
Pod Status & Details #
List Pods & Pod Details #
# Check pod status
kubectl get pods
# Shell output: Wait till both containers a ready
NAME READY STATUS RESTARTS AGE
nginx-alpine-pod 2/2 Running 0 11s
# List pod details
kubectl describe pod nginx-alpine-pod
# Shell output:
...
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 26s default-scheduler Successfully assigned default/nginx-alpine-pod to ubuntu3
Normal Pulling 26s kubelet Pulling image "nginx"
Normal Pulled 25s kubelet Successfully pulled image "nginx" in 979ms (979ms including waiting). Image size: 72955450 bytes.
Normal Created 25s kubelet Created container nginx-container
Normal Started 25s kubelet Started container nginx-container
Normal Pulling 25s kubelet Pulling image "alpine"
Normal Pulled 23s kubelet Successfully pulled image "alpine" in 2.543s (2.543s including waiting). Image size: 3634744 bytes.
Normal Created 23s kubelet Created container alpine-container
Normal Started 23s kubelet Started container alpine-container
Alpine Container Logs #
In the logs of the Alpine container, the curled output of the Nginx service is visible:
# Check the logs of the "alpine-container" in the "nginx-alpine-pod"
kubectl logs nginx-alpine-pod -c alpine-container --tail=30
# Shell output:
...
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
Find Container on Kubernetes Node #
Find Worker Node #
# List on which node the pods runs
kubectl get pods -o wide
# Shell output:
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-alpine-pod 2/2 Running 0 6m21s 10.233.74.71 node4 <none> <none>
Find Container Runtime #
# Use the following command to find the container runtime
kubectl describe node node4
# Shell output:
...
Container Runtime Version: containerd://1.7.16
List Containers on Node #
Log in to the Kubernetes node where the pod runs, to check the container status:
# List all running containers managed by containerd within the Kubernetes namespace (k8s.io)
sudo ctr -n k8s.io containers list
# Shell output:
CONTAINER IMAGE RUNTIME
...
0a68e2f17ff0a92ed5d7ee14d4041362ab62851377a34a153c0a04c4e047a772 docker.io/library/alpine:latest io.containerd.runc.v2
1ea8b91d268c81819ccfd2a8d41936d53f545f2a8933a6de28e9c34a133c391d docker.io/library/nginx:1.25.2-alpine io.containerd.runc.v2
# List detailed information about a specific container
sudo ctr -n k8s.io containers info container-id
sudo ctr -n k8s.io containers info 0a68e2f17ff0a92ed5d7ee14d4041362ab62851377a34a153c0a04c4e047a772
Delete the Pod #
# Delete the pod
kubectl delete pod nginx-alpine-pod