Ingress resource definition in Kubernetes - Mini Project: Build & Apply

Ingress Resource Definition

📖 Scenario: You are setting up a simple web application on Kubernetes. You want to allow users to access your app through a friendly web address. To do this, you will create an Ingress resource that directs traffic to your app's service.

🎯 Goal: Build a Kubernetes Ingress resource definition that routes HTTP traffic from the host myapp.example.com to a service named myapp-service on port 80.

📋 What You'll Learn

Create a YAML manifest for an Ingress resource named myapp-ingress in the default namespace.

Set the host to myapp.example.com.

Route all HTTP requests (path /) to the service myapp-service on port 80.

Use the networking.k8s.io/v1 API version.

💡 Why This Matters

🌍 Real World

Ingress resources are used in Kubernetes to manage external access to services inside the cluster. They provide a simple way to route traffic based on hostnames and paths.

💼 Career

Understanding Ingress definitions is essential for Kubernetes administrators and DevOps engineers to expose applications securely and efficiently.

1

Create the basic Ingress resource skeleton

Create a YAML manifest starting with apiVersion: networking.k8s.io/v1, kind: Ingress, and metadata with name: myapp-ingress and namespace: default.

Kubernetes

# Your code here

Hint

Start by defining the API version, kind, and metadata fields for the Ingress resource.

2

Add the Ingress rules with host and path

Add a spec section with rules that define the host as myapp.example.com and a single HTTP path /.

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myapp-ingress
  namespace: default
# Add spec with rules, host, and path here

Hint

Use spec.rules to define the host and HTTP paths. Use pathType: Prefix for the path.

3

Configure the backend service and port

Under the path, add a backend section that points to the service named myapp-service on port 80.

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myapp-ingress
  namespace: default
spec:
  rules:
  - host: myapp.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
# Add backend service name and port here

Hint

Use the backend.service.name and backend.service.port.number fields to specify the target service and port.

4

Display the complete Ingress manifest

Print the full YAML manifest for the Ingress resource named myapp-ingress with the host myapp.example.com routing path / to service myapp-service on port 80.

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myapp-ingress
  namespace: default
spec:
  rules:
  - host: myapp.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: myapp-service
            port:
              number: 80
# Display the complete manifest here

Hint

Review the full manifest to ensure all parts are included and correctly indented.

Practice

1. What is the main purpose of a Kubernetes Ingress resource?

easy

A. To route external HTTP(S) traffic to internal services based on rules

B. To store configuration data for pods

C. To manage persistent storage volumes

D. To schedule pods on specific nodes

Solution

1. Step 1: Understand Ingress role

   An Ingress resource defines rules to route external traffic to services inside the cluster.

2. Step 2: Compare with other resources

   ConfigMaps store config, PersistentVolumes manage storage, and scheduling is done by the scheduler, not Ingress.

3. Final Answer:

   To route external HTTP(S) traffic to internal services based on rules -> Option A

4. Quick Check:

   Ingress routes external traffic [OK]

Hint: Ingress routes external traffic to services inside Kubernetes [OK]

Common Mistakes:

• Confusing Ingress with ConfigMap or PersistentVolume
• Thinking Ingress schedules pods
• Assuming Ingress manages storage

2. Which of the following is the correct minimal YAML snippet to define an Ingress that routes /app path to a service named my-service on port 80?

easy

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

B. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /app\n pathType: Prefix\n backend:\n service:\n name: my-service\n port:\n number: 80

C. apiVersion: v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - host: example.com\n http:\n paths:\n - path: /app\n backend:\n serviceName: my-service\n servicePort: 80

D. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /app\n backend:\n service:\n name: my-service\n port: 8080

Solution

1. Step 1: Check apiVersion and kind

   Correct apiVersion for Ingress is networking.k8s.io/v1 and kind is Ingress.

2. Step 2: Validate backend service and port

   apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /app\n pathType: Prefix\n backend:\n service:\n name: my-service\n port:\n number: 80 uses correct new syntax with service name and port number 80 matching the question.

3. Final Answer:

   YAML with apiVersion networking.k8s.io/v1, kind Ingress, path /app, service my-service, port 80 -> Option B

4. Quick Check:

   Correct Ingress YAML uses networking.k8s.io/v1 and service port number [OK]

Hint: Use networking.k8s.io/v1 and service.port.number for Ingress backend [OK]

Common Mistakes:

• Using old apiVersion v1 for Ingress
• Using serviceName/servicePort instead of service.name/port.number
• Wrong port number in backend
• Defining Service instead of Ingress

3. Given this Ingress YAML snippet, what host and path will route traffic to web-service?

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: test-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

medium

A. Traffic to host example.com and path starting with /web

B. Traffic to any host and path /web

C. Traffic to host example.com and any path

D. Traffic to host example.com and path exactly /web

Solution

1. Step 1: Identify host and path in rules

   The rule specifies host example.com and path /web with pathType Prefix.

2. Step 2: Understand pathType Prefix meaning

   Prefix means any path starting with /web will match, not just exactly /web.

3. Final Answer:

   Traffic to host example.com and path starting with /web -> Option A

4. Quick Check:

   Host and prefix path routing = Traffic to host example.com and path starting with /web [OK]

Hint: Prefix path matches all paths starting with given string [OK]

Common Mistakes:

• Assuming path matches exactly instead of prefix
• Ignoring host field and assuming any host
• Confusing pathType Prefix with Exact

4. You applied this Ingress YAML but traffic is not routing correctly:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: bad-ingress
spec:
  rules:
  - http:
      paths:
      - path: /app
        pathType: Prefix
        backend:
          serviceName: app-service
          servicePort: 80

What is the likely cause of the problem?

medium

A. Missing host field in rules

B. Incorrect apiVersion for Ingress

C. Using deprecated backend syntax serviceName and servicePort instead of service.name and service.port.number

D. Missing metadata name field

Solution

1. Step 1: Check backend syntax in Ingress spec

   The YAML uses old syntax with serviceName and servicePort which is deprecated in networking.k8s.io/v1.

2. Step 2: Confirm correct syntax

   Correct syntax uses service.name and service.port.number fields under backend.service.

3. Final Answer:

   Using deprecated backend syntax serviceName and servicePort instead of service.name and service.port.number -> Option C

4. Quick Check:

   Use service.name and service.port.number in Ingress backend [OK]

Hint: Use service.name and service.port.number for backend in networking.k8s.io/v1 [OK]

Common Mistakes:

• Using old backend syntax causing Ingress controller to ignore rules
• Assuming missing host always breaks routing
• Confusing apiVersion correctness
• Forgetting metadata name

5. You want to expose two services, service-a and service-b, on the same IP but different paths /a and /b. Which Ingress YAML snippet correctly defines this?

hard

A. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - host: example.com\n http:\n paths:\n - path: /a\n pathType: Prefix\n backend:\n service:\n name: service-a\n port:\n number: 80

B. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - host: example.com\n http:\n paths:\n - path: /a\n backend:\n serviceName: service-a\n servicePort: 80\n - path: /b\n backend:\n serviceName: service-b\n servicePort: 80

C. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /a\n pathType: Exact\n backend:\n serviceName: service-a\n servicePort: 80\n - path: /b\n pathType: Exact\n backend:\n serviceName: service-b\n servicePort: 80

D. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /a\n pathType: Prefix\n backend:\n service:\n name: service-a\n port:\n number: 80\n - path: /b\n pathType: Prefix\n backend:\n service:\n name: service-b\n port:\n number: 80

Solution

1. Step 1: Check apiVersion and kind

   All options use correct apiVersion and kind for Ingress.

2. Step 2: Validate backend syntax and multiple paths

   apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /a\n pathType: Prefix\n backend:\n service:\n name: service-a\n port:\n number: 80\n - path: /b\n pathType: Prefix\n backend:\n service:\n name: service-b\n port:\n number: 80 correctly uses service.name and service.port.number with two paths under one rule without host, matching the requirement.

3. Step 3: Compare pathType usage

   Prefix pathType allows routing all requests starting with /a or /b, which is typical for path-based routing.

4. Final Answer:

   Ingress with two paths /a and /b routing to service-a and service-b using correct backend syntax -> Option D

5. Quick Check:

   Multiple paths with service.name and port.number = apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: multi-service-ingress\nspec:\n rules:\n - http:\n paths:\n - path: /a\n pathType: Prefix\n backend:\n service:\n name: service-a\n port:\n number: 80\n - path: /b\n pathType: Prefix\n backend:\n service:\n name: service-b\n port:\n number: 80 [OK]

Hint: Use one rule with multiple paths and service.name/port.number [OK]

Common Mistakes:

• Using deprecated backend syntax serviceName/servicePort
• Missing one of the paths or services
• Using pathType Exact which may limit routing
• Defining only one path instead of two