Why Path-based routing in Kubernetes? - Purpose & Use Cases

The Big Idea

What if one simple URL could magically send every visitor exactly where they need to go?

The Scenario

Imagine you have a website with different sections like blog, shop, and support, each running on separate servers. Without path-based routing, you must tell users exactly which server address to visit for each section.

The Problem

This manual way is confusing for users and hard to manage. You must update links everywhere if servers change. Also, directing traffic manually wastes time and causes mistakes, like sending users to the wrong place.

The Solution

Path-based routing lets you use one main address and automatically sends users to the right section based on the URL path. This means simpler URLs, easier management, and smooth user experience without manual redirects.

Before vs After

✗ Before

User visits blog.example.com or shop.example.com separately

✓ After

User visits example.com/blog or example.com/shop routed automatically

What It Enables

It enables seamless traffic control so users reach the right service effortlessly through clear, simple URLs.

Real Life Example

A company hosts its marketing site, online store, and help center on different servers but uses path-based routing to let visitors access all via example.com with paths like /store and /help.

Key Takeaways

Manual routing is confusing and error-prone.

Path-based routing automates directing users by URL paths.

This simplifies management and improves user experience.

Practice

1. What does path-based routing in Kubernetes Ingress do?

easy

A. It sends traffic to different services based on URL paths.

B. It balances traffic evenly between all nodes.

C. It encrypts traffic between pods.

D. It schedules pods on specific nodes.

Solution

1. Step 1: Understand Ingress role

   Kubernetes Ingress manages external access to services, often HTTP.

2. Step 2: Identify path-based routing function

   Path-based routing directs requests to services depending on the URL path.

3. Final Answer:

   It sends traffic to different services based on URL paths. -> Option A

4. Quick Check:

   Path-based routing = directing traffic by URL path [OK]

Hint: Remember: path-based routing matches URL paths to services [OK]

Common Mistakes:

• Confusing path-based routing with load balancing
• Thinking it schedules pods
• Assuming it encrypts traffic

2. Which is the correct way to specify a path in a Kubernetes Ingress rule for path-based routing?

easy

A. url: /app
urlType: Prefix

B. route: /app
routeType: Exact

C. servicePath: /app
serviceType: Exact

D. path: /app
pathType: Prefix

Solution

1. Step 1: Recall Ingress rule syntax

   Ingress rules use path and pathType keys to define routing.

2. Step 2: Match correct keys and values

   Correct keys are path and pathType, with values like '/app' and 'Prefix'.

3. Final Answer:

   path: /app pathType: Prefix -> Option D

4. Quick Check:

   Use path and pathType keys for routing [OK]

Hint: Look for 'path' and 'pathType' keys in Ingress rules [OK]

Common Mistakes:

• Using wrong keys like 'route' or 'url'
• Mixing up pathType values
• Missing pathType field

3. Given this Ingress snippet, which service will receive traffic for URL path '/shop/cart'?

rules:
- http:
    paths:
    - path: /shop
      pathType: Prefix
      backend:
        service:
          name: shop-service
          port:
            number: 80
    - path: /blog
      pathType: Prefix
      backend:
        service:
          name: blog-service
          port:
            number: 80

medium

A. blog-service

B. shop-service

C. default backend

D. No service matches

Solution

1. Step 1: Check path matching rules

   Path '/shop/cart' starts with '/shop', matching the first path rule with pathType Prefix.

2. Step 2: Identify backend service

   The matching path routes to 'shop-service' on port 80.

3. Final Answer:

   shop-service -> Option B

4. Quick Check:

   Prefix match '/shop' routes to shop-service [OK]

Hint: Prefix path matches any URL starting with it [OK]

Common Mistakes:

• Choosing blog-service for /shop/cart
• Assuming no match for subpaths
• Confusing default backend with path rules

4. You wrote this Ingress rule but traffic to '/api' is not routed correctly:

paths:
- path: api
  pathType: Prefix
  backend:
    service:
      name: api-service
      port:
        number: 80

What is the likely error?

medium

A. Incorrect pathType value

B. Service name is invalid

C. Missing leading slash in path value

D. Port number must be a string

Solution

1. Step 1: Check path syntax

   Paths must start with a leading slash '/' to match URLs correctly.

2. Step 2: Identify missing slash

   The path is 'api' instead of '/api', so it won't match requests starting with '/api'.

3. Final Answer:

   Missing leading slash in path value -> Option C

4. Quick Check:

   Paths need leading '/' for correct matching [OK]

Hint: Always start path with '/' in Ingress rules [OK]

Common Mistakes:

• Omitting leading slash in path
• Using wrong pathType values
• Assuming port number must be string

5. You want to route traffic so that: - '/app' goes to 'app-service' - '/app/admin' goes to 'admin-service' Which Ingress path rules correctly implement this path-based routing?

hard

A. - path: /app/admin
pathType: Prefix
backend:
service:
name: admin-service
port:
number: 80
- path: /app
pathType: Prefix
backend:
service:
name: app-service
port:
number: 80

B. - path: /app
pathType: Prefix
backend:
service:
name: app-service
port:
number: 80
- path: /app/admin
pathType: Prefix
backend:
service:
name: admin-service
port:
number: 80

C. - path: /app
pathType: Exact
backend:
service:
name: app-service
port:
number: 80
- path: /app/admin
pathType: Exact
backend:
service:
name: admin-service
port:
number: 80

D. - path: /app/admin
pathType: Exact
backend:
service:
name: admin-service
port:
number: 80
- path: /app
pathType: Exact
backend:
service:
name: app-service
port:
number: 80

Solution

1. Step 1: Understand path matching order

   Ingress matches paths in order; more specific paths must come first to avoid being shadowed.

2. Step 2: Check rule order and pathType

   Placing '/app/admin' before '/app' with pathType Prefix ensures '/app/admin' routes to admin-service, others to app-service.

3. Final Answer:

   Place '/app/admin' rule before '/app' rule with Prefix pathType -> Option A

4. Quick Check:

   Order specific paths first for correct routing [OK]

Hint: List longer paths before shorter ones in Ingress rules [OK]

Common Mistakes:

• Placing general path before specific path
• Using Exact pathType causing no subpath matches
• Ignoring rule order importance