apiVersion: v1
kind: Pod
metadata:
name: nginx-sidecar-pod
labels:
app: nginx-sidecar
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
volumeMounts:
- name: shared-logs
mountPath: ...

This one will show how multiple containers in a single Pod can share data and work together, just like microservices collaborating closely inside one unit.

---

🎯 Goal

Create a multi-container Pod with:

• One main container running NGINX
• One sidecar container that tails NGINX access logs and prints them to its own stdout (mimicking a log forwarder)

This demonstrates the Sidecar Pattern — where an auxiliary container extends or supports the main container’s function.

---

🧩 Step 1: Create YAML for Multi-Container Pod

Create a file named nginx-sidecar-pod.yaml

apiVersion: v1
kind: Pod
metadata:
name: nginx-sidecar-pod
labels:
app: nginx-sidecar
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
volumeMounts:
- name: shared-logs
mountPath: /var/log/nginx
- name: sidecar-logger
image: busybox
command: ["/bin/sh", "-c"]
args:
- |
echo "📜 Sidecar started. Monitoring /var/log/nginx/access.log...";
tail -n+1 -F /var/log/nginx/access.log
volumeMounts:
- name: shared-logs
mountPath: /var/log/nginx
volumes:
- name: shared-logs
emptyDir: {}

---

🧠 How It Works

• Both containers share a volume (emptyDir) at /var/log/nginx.
• NGINX writes logs to /var/log/nginx/access.log.
• The sidecar container continuously tails that file and outputs to its stdout.
• Kubernetes logs aggregation will show both containers’ logs.

---

🚀 Step 2: Create YAML for Service

Create nginx-sidecar-service.yaml:

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

---

🚀 Step 3: Apply the YAML

kubectl apply -f nginx-sidecar-pod.yaml
kubectl apply -f nginx-sidecar-service.yaml

✅ Output:

pod/nginx-sidecar-pod created
service/nginx-sidecar-service created

---

🔍 Step 4: Verify the Pod

kubectl get pods -o wide

Expected:

NAME                READY   STATUS    RESTARTS   AGE   IP           NODE
nginx-sidecar-pod   2/2     Running   0          20s   10.32.0.18   gke-mycluster-default-pool-xxxx

Notice there are two containers inside one Pod.

---

🧪 Step 5: Generate Logs

Run a temporary busybox Pod and hit the NGINX endpoint a few times:

kubectl run curl-pod --image=busybox -it --rm -- /bin/sh

Inside the shell:

wget -qO- http://nginx-sidecar-pod
exit

---

🪵 Step 6: Check Sidecar Logs

Now check the sidecar container’s logs:

kubectl logs nginx-sidecar-pod -c sidecar-logger

You’ll see output like:

📜 Sidecar started. Monitoring /var/log/nginx/access.log...
10.32.0.19 - - [07/Nov/2025:12:45:34 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget" "-"

🎉 You’ve just demonstrated the Sidecar pattern — where a helper container monitors and reacts to another container’s output.

---

🧹 Cleanup (Optional)

kubectl delete svc nginx-sidecar-service
kubectl delete pod nginx-sidecar-pod

---

🧭 Architecture Visualization

+-------------------------------------------------------+
|                Pod: nginx-sidecar-pod                 |
|-------------------------------------------------------|
|  [ nginx container ]        [ sidecar-logger ]        |
|  /var/log/nginx <-- shared emptyDir volume --> /var/log/nginx |
+-------------------------------------------------------+

• nginx → serves traffic and writes logs
• sidecar-logger → reads and outputs those logs

---

🌟 Thanks for reading! If this post added value, a like ❤️, follow, or share would encourage me to keep creating more content.

---

— Latchu | Senior DevOps & Cloud Engineer

☁️ AWS | GCP | ☸️ Kubernetes | 🔐 Security | ⚡ Automation 📌 Sharing hands-on guides, best practices & real-world cloud solutions