Ingress vs LoadBalancer Service decision in Kubernetes - CLI Comparison

Introduction

When you want to expose your applications running in Kubernetes to the outside world, you need a way to route external traffic. Ingress and LoadBalancer services are two common methods to do this, each solving different problems about how traffic reaches your app.

When you have multiple services and want to route traffic to them using one external IP with different URLs or paths.

When you want a simple way to expose a single service directly to the internet with its own IP address.

When you want to use advanced routing rules like SSL termination or host-based routing.

When your cloud provider supports automatic external load balancers for services.

When you want to reduce the number of public IPs used by sharing one IP across many services.

Commands

This command creates a Service of type LoadBalancer that exposes your app with a cloud provider's external IP address.

Terminal

kubectl apply -f loadbalancer-service.yaml

Expected Output

service/my-loadbalancer-service created

This command checks the status of the LoadBalancer service and shows the external IP assigned by the cloud provider.

Terminal

kubectl get svc my-loadbalancer-service

Expected Output

NAME                     TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE

my-loadbalancer-service  LoadBalancer   10.96.0.1       34.123.45.67     80:32456/TCP   1m

This command creates an Ingress resource that routes external traffic to different services based on rules like URL paths or hostnames.

Terminal

kubectl apply -f ingress.yaml

Expected Output

ingress.networking.k8s.io/my-ingress created

This command shows the external IP or hostname assigned to the Ingress controller that handles routing traffic to your services.

Terminal

kubectl get ingress my-ingress

Expected Output

NAME         CLASS    HOSTS               ADDRESS          PORTS   AGE

my-ingress   <none>   example.com         34.123.45.89     80      1m

Key Concept

If you remember nothing else from this pattern, remember: Use LoadBalancer service for simple direct exposure of one app, and use Ingress to route traffic to many apps with one external IP and flexible rules.

Common Mistakes

Creating multiple LoadBalancer services for many apps without considering IP limits.

Cloud providers limit the number of external IPs and it can be costly or inefficient.

Use an Ingress resource to share one external IP and route traffic to multiple services.

Applying an Ingress resource without installing an Ingress controller.

Ingress resources need a controller to actually route traffic; without it, the Ingress does nothing.

Install a supported Ingress controller like NGINX Ingress or cloud provider's controller before creating Ingress resources.

Summary

Use LoadBalancer service to expose a single app with its own external IP.

Use Ingress to route traffic to multiple services using one external IP and rules.

Check service or ingress status with kubectl get commands to find assigned external IPs.

Practice

1. Which Kubernetes service type should you choose if you want to expose a single application with its own external IP address?

easy

A. LoadBalancer Service

B. Ingress Controller

C. ClusterIP Service

D. NodePort Service

Solution

1. Step 1: Understand service types

   LoadBalancer Service exposes an app with its own external IP, making it directly accessible.

2. Step 2: Compare with Ingress

   Ingress routes multiple apps through one IP, so it's not for single app direct exposure.

3. Final Answer:

   LoadBalancer Service -> Option A

4. Quick Check:

   Single app direct IP = LoadBalancer Service [OK]

Hint: Single app direct IP? Use LoadBalancer Service [OK]

Common Mistakes:

• Confusing Ingress with LoadBalancer for single app
• Choosing ClusterIP which is internal only
• Selecting NodePort which exposes on node ports, not external IP

2. Which of the following is the correct way to define a LoadBalancer service in a Kubernetes YAML manifest?

easy

A. apiVersion: networking.k8s.io/v1\nkind: LoadBalancer\nmetadata:\n name: my-service\nspec:\n selector:\n app: my-app\n ports:\n - protocol: TCP\n port: 80\n targetPort: 8080

B. apiVersion: v1\nkind: Service\nmetadata:\n name: my-service\nspec:\n type: Ingress\n selector:\n app: my-app\n ports:\n - protocol: TCP\n port: 80\n targetPort: 8080

C. apiVersion: v1\nkind: Service\nmetadata:\n name: my-service\nspec:\n type: NodePort\n selector:\n app: my-app\n ports:\n - protocol: TCP\n port: 80\n targetPort: 8080

D. apiVersion: v1\nkind: Service\nmetadata:\n name: my-service\nspec:\n type: LoadBalancer\n selector:\n app: my-app\n ports:\n - protocol: TCP\n port: 80\n targetPort: 8080

Solution

1. Step 1: Check apiVersion and kind

   Service resources use apiVersion: v1 and kind: Service.

2. Step 2: Confirm service type

   LoadBalancer type is set under spec.type to expose external IP.

3. Final Answer:

   YAML with kind Service and type LoadBalancer -> Option D

4. Quick Check:

   LoadBalancer service YAML uses kind Service and type LoadBalancer [OK]

Hint: LoadBalancer service uses kind Service and type LoadBalancer [OK]

Common Mistakes:

• Using kind LoadBalancer instead of Service
• Setting type to Ingress which is invalid for Service
• Confusing NodePort with LoadBalancer

3. Given this scenario: You have two apps, app1 and app2, and want to expose both externally using one IP with different paths. Which Kubernetes resource will handle this correctly?

medium

A. Two LoadBalancer Services, one for each app

B. One Ingress resource with path rules for app1 and app2

C. Two NodePort Services with different ports

D. One ClusterIP Service with multiple selectors

Solution

1. Step 1: Understand routing multiple apps on one IP

   Ingress allows routing multiple apps through one IP using path or hostname rules.

2. Step 2: Compare with LoadBalancer and others

   LoadBalancer exposes one app per IP; NodePort uses node ports, not one IP; ClusterIP is internal only.

3. Final Answer:

   One Ingress resource with path rules -> Option B

4. Quick Check:

   Multiple apps, one IP = Ingress with path rules [OK]

Hint: Multiple apps, one IP? Use Ingress with paths [OK]

Common Mistakes:

• Using multiple LoadBalancers wasting IPs
• Choosing NodePort which needs manual port management
• Thinking ClusterIP exposes externally

4. You created a LoadBalancer service but it never gets an external IP assigned. What is the most likely cause?

medium

A. You forgot to set spec.type to ClusterIP

B. Ingress controller is missing

C. Your Kubernetes cluster is running on a platform without LoadBalancer support

D. You used NodePort instead of LoadBalancer

Solution

1. Step 1: Check platform support for LoadBalancer

   Some clusters (like bare metal) do not support automatic external IP assignment for LoadBalancer services.

2. Step 2: Verify service type and controller

   Spec.type must be LoadBalancer, not ClusterIP; Ingress controller is unrelated; NodePort is different service type.

3. Final Answer:

   Platform lacks LoadBalancer support -> Option C

4. Quick Check:

   No external IP = platform lacks LoadBalancer support [OK]

Hint: No external IP? Check platform LoadBalancer support [OK]

Common Mistakes:

• Confusing ClusterIP with LoadBalancer type
• Assuming Ingress controller assigns LoadBalancer IP
• Mixing NodePort with LoadBalancer service

5. You want to minimize cloud costs while exposing 5 different apps externally. Which approach is best?

hard

A. Use one Ingress resource to route all 5 apps through a single LoadBalancer IP

B. Use ClusterIP services and expose each with a separate external IP

C. Use 5 NodePort services and expose nodes directly

D. Create 5 LoadBalancer services, one per app

Solution

1. Step 1: Understand cost implications of LoadBalancer IPs

   Each LoadBalancer service usually gets a separate external IP, increasing cloud costs.

2. Step 2: Use Ingress for cost efficiency

   Ingress lets multiple apps share one external IP with routing rules, saving costs.

3. Final Answer:

   One Ingress resource with single LoadBalancer IP -> Option A

4. Quick Check:

   Multiple apps, minimize cost = Ingress with one LoadBalancer IP [OK]

Hint: Multiple apps, one IP saves cost: use Ingress [OK]

Common Mistakes:

• Creating multiple LoadBalancers wasting IPs and money
• Using NodePort exposes nodes, less secure and complex
• ClusterIP cannot expose apps externally