Why Ingress manages external access in Kubernetes - See It in Action

Why Ingress Manages External Access in Kubernetes

📖 Scenario: You are working with a Kubernetes cluster that runs several web applications. You want to control how users from outside the cluster can reach these applications. Kubernetes provides a way to manage this external access using a resource called Ingress.

🎯 Goal: Learn how to create a simple data structure representing services and their ports, add a configuration for an Ingress controller, apply the logic to map external paths to services, and finally display the Ingress rules that manage external access.

📋 What You'll Learn

Create a dictionary called services with exact service names and ports

Add a variable called ingress_controller with the value 'nginx'

Create a dictionary called ingress_rules that maps URL paths to service names using a for loop

Print the ingress_rules dictionary to show how Ingress manages external access

💡 Why This Matters

🌍 Real World

In real Kubernetes clusters, Ingress resources control how users from outside the cluster access internal services. This project models that mapping simply.

💼 Career

Understanding Ingress is key for DevOps roles managing Kubernetes clusters, as it helps configure secure and organized external access to applications.

1

Create the services dictionary

Create a dictionary called services with these exact entries: 'webapp': 80, 'api': 8080, 'auth': 9090.

Kubernetes

# Create the services dictionary with exact service names and ports
# Your code here

Hint

Use curly braces to create a dictionary with keys as service names and values as ports.

2

Add the Ingress controller configuration

Add a variable called ingress_controller and set it to the string 'nginx'.

Kubernetes

services = {'webapp': 80, 'api': 8080, 'auth': 9090}
# Add the ingress_controller variable set to 'nginx'
# Your code here

Hint

Just assign the string 'nginx' to the variable ingress_controller.

3

Create Ingress rules mapping paths to services

Create a dictionary called ingress_rules that maps these URL paths to service names: '/app' to 'webapp', '/api' to 'api', and '/login' to 'auth'. Use a for loop with variables path and service to build this dictionary from a list of tuples.

Kubernetes

services = {'webapp': 80, 'api': 8080, 'auth': 9090}
ingress_controller = 'nginx'
# Create ingress_rules dictionary using a for loop
# Your code here

Hint

Create an empty dictionary, then fill it by looping over the list of path-service pairs.

4

Display the Ingress rules

Write a print statement to display the ingress_rules dictionary.

Kubernetes

services = {'webapp': 80, 'api': 8080, 'auth': 9090}
ingress_controller = 'nginx'
paths = [('/app', 'webapp'), ('/api', 'api'), ('/login', 'auth')]
ingress_rules = {}
for path, service in paths:
    ingress_rules[path] = service
# Print the ingress_rules dictionary
# Your code here

Hint

Use print(ingress_rules) to show the final mapping.

Practice

1. What is the primary role of an Ingress in Kubernetes?

easy

A. To manage external access to services inside the cluster

B. To store configuration data for pods

C. To schedule pods on nodes

D. To monitor resource usage of containers

Solution

1. Step 1: Understand Ingress purpose

   Ingress is designed to control how external users access services running inside Kubernetes.

2. Step 2: Compare with other components

   Other components like ConfigMaps store data, schedulers place pods, and metrics monitor usage, but Ingress manages external access.

3. Final Answer:

   To manage external access to services inside the cluster -> Option A

4. Quick Check:

   Ingress controls external access = C [OK]

Hint: Ingress controls outside traffic to services [OK]

Common Mistakes:

• Confusing Ingress with ConfigMap or Scheduler
• Thinking Ingress manages internal pod scheduling
• Assuming Ingress monitors resource usage

2. Which of the following is the correct basic syntax to define an Ingress resource in YAML?

easy

A. apiVersion: v1\nkind: Service\nmetadata:\n name: example-ingress\nspec:\n selector:\n app: example\n ports:\n - protocol: TCP\n port: 80\n targetPort: 9376

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

C. apiVersion: apps/v1\nkind: Deployment\nmetadata:\n name: example-ingress\nspec:\n replicas: 3\n selector:\n matchLabels:\n app: example

D. apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - host: example.com\n tcp:\n ports:\n - port: 80\n backend:\n serviceName: example-service\n servicePort: 80

Solution

1. Step 1: Identify correct Ingress syntax

   Ingress uses apiVersion networking.k8s.io/v1, kind Ingress, and defines rules with host and http paths.

2. Step 2: Check options for correct fields

   apiVersion: networking.k8s.io/v1\nkind: Ingress\nmetadata:\n name: example-ingress\nspec:\n rules:\n - host: example.com\n http:\n paths:\n - path: /\n pathType: Prefix\n backend:\n service:\n name: example-service\n port:\n number: 80 matches the correct structure with service name and port under backend. apiVersion: v1\nkind: Service\nmetadata:\n name: example-ingress\nspec:\n selector:\n app: example\n ports:\n - protocol: TCP\n port: 80\n targetPort: 9376 is a Service definition. The other options define a Deployment or incorrectly use a tcp field.

3. Final Answer:

   apiVersion: networking.k8s.io/v1 kind: Ingress spec: rules: - host: example.com http: paths: - path: / pathType: Prefix backend: service: name: example-service port: number: 80 -> Option B

4. Quick Check:

   Ingress YAML syntax = A [OK]

Hint: Ingress YAML uses rules with host and http paths [OK]

Common Mistakes:

• Confusing Service or Deployment YAML with Ingress
• Using tcp instead of http in rules
• Incorrect apiVersion or kind for Ingress

3. Given this Ingress rule snippet, what hostname will route traffic to my-service?

spec:
  rules:
  - host: app.example.com
    http:
      paths:
      - path: /app
        pathType: Prefix
        backend:
          service:
            name: my-service
            port:
              number: 8080

medium

A. app.example.com

B. example.com

C. my-service

D. app

Solution

1. Step 1: Identify the host in the Ingress rule

   The host field is set to app.example.com, which defines the hostname for routing.

2. Step 2: Understand routing based on host

   Traffic to app.example.com with path prefix /app routes to my-service on port 8080.

3. Final Answer:

   app.example.com -> Option A

4. Quick Check:

   Host in rule = app.example.com [OK]

Hint: Look for host field in Ingress rules [OK]

Common Mistakes:

• Confusing service name with hostname
• Ignoring the host field and picking path or service name
• Choosing partial strings like 'app' instead of full hostname

4. You created an Ingress resource but external traffic is not reaching your service. Which of these is a likely cause?

medium

A. The pod image is missing a label

B. The cluster has no nodes

C. The service port is set to 0

D. The Ingress controller is not installed or running

Solution

1. Step 1: Check Ingress controller presence

   Ingress resources need an Ingress controller to process rules and route traffic. Without it, Ingress does nothing.

2. Step 2: Evaluate other options

   Pod labels or service ports affect internal routing but won't stop Ingress from receiving traffic. No nodes means cluster is down, but question focuses on Ingress.

3. Final Answer:

   The Ingress controller is not installed or running -> Option D

4. Quick Check:

   Ingress needs controller to route traffic = B [OK]

Hint: Ingress needs a controller running to work [OK]

Common Mistakes:

• Ignoring the need for an Ingress controller
• Blaming pod labels for external access issues
• Confusing service port 0 with Ingress failure

5. You want to expose two services, service-a and service-b, on the same domain but different paths using Ingress. Which configuration correctly achieves this?

hard

A. Use a LoadBalancer service type for each service instead of Ingress

B. Create two Ingress resources with the same host example.com, each with one path for service-a and service-b

C. Define one Ingress with rules for host example.com and paths /a routing to service-a, /b routing to service-b

D. Expose service-a and service-b on different ports without Ingress

Solution

1. Step 1: Understand Ingress path routing

   Ingress can route different URL paths on the same host to different services using rules with multiple paths.

2. Step 2: Compare options for best practice

   Define one Ingress with rules for host example.com and paths /a routing to service-a, /b routing to service-b uses one Ingress with multiple paths, which is efficient and standard. Create two Ingress resources with the same host example.com, each with one path for service-a and service-b may cause conflicts. Options C and D avoid Ingress and don't meet the requirement.

3. Final Answer:

   Define one Ingress with rules for host example.com and paths /a and /b routing to respective services -> Option C

4. Quick Check:

   One Ingress, multiple paths = A [OK]

Hint: Use one Ingress with multiple paths for same host [OK]

Common Mistakes:

• Creating multiple Ingresses with same host causing conflicts
• Using LoadBalancer instead of Ingress for path routing
• Exposing services on different ports without hostname routing