Path-based routing in Kubernetes - Step-by-Step Execution

Process Flow - Path-based routing

Incoming HTTP Request

↓

Check URL Path

↓

Route to Service1

↓

Response

Incoming requests are checked for their URL path and routed to different services based on the path prefix.

Execution Sample

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - http:
      paths:
      - path: /app1
        pathType: Prefix
        backend:
          service:
            name: service1
            port:
              number: 80
      - path: /app2
        pathType: Prefix
        backend:
          service:
            name: service2
            port:
              number: 80

Ingress resource routes requests with path /app1 to service1 and /app2 to service2.

Process Table

Step	Incoming Request Path	Path Match Check	Service Routed To	Action
1	/app1/home	Matches /app1 prefix	service1	Request routed to service1
2	/app2/dashboard	Matches /app2 prefix	service2	Request routed to service2
3	/app3/info	No matching path prefix	default backend or 404	Request routed to default or rejected

💡 Routing stops after matching the first path prefix or falls back to default backend.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3
request_path	none	/app1/home	/app2/dashboard	/app3/info
matched_path	none	/app1	/app2	none
routed_service	none	service1	service2	default backend or 404

Key Moments - 2 Insights

Why does a request to /app3/info not get routed to service1 or service2?

Because /app3 does not match any defined path prefixes (/app1 or /app2) in the ingress rules, so it goes to the default backend or returns 404 as shown in execution_table row 3.

What happens if two paths overlap, like /app and /app1?

The ingress controller matches the first path prefix that fits the request path. Order matters, so the more specific path should be listed first to avoid unexpected routing.

Visual Quiz - 3 Questions

Look at the execution table, which service handles the request path '/app2/dashboard'?

A service1

B service2

C default backend

D No service

💡 Hint

Check execution_table row 2 under 'Service Routed To'

At which step does the routing fall back to the default backend or 404?

A Step 1

B Step 2

C Step 3

D Never

💡 Hint

Look at execution_table row 3 'Path Match Check' and 'Service Routed To'

If a new path /app is added before /app1, which service will handle '/app1/home' requests?

A service for /app

B default backend

C service1

D No service

💡 Hint

Path matching uses first match order; adding /app before /app1 changes routing as per key_moments explanation

Concept Snapshot

Path-based routing in Kubernetes Ingress:
- Define multiple paths under rules.http.paths
- Use pathType: Prefix for prefix matching
- Requests routed to backend service matching first path prefix
- Order of paths matters for overlapping prefixes
- Unmatched paths go to default backend or 404

Full Transcript

Path-based routing in Kubernetes Ingress works by checking the incoming HTTP request's URL path. The ingress controller compares the path against defined prefixes in the ingress rules. When a match is found, the request is routed to the corresponding backend service. If no path matches, the request goes to the default backend or returns a 404 error. The order of path definitions is important because the first matching prefix is used for routing. This allows different services to handle different parts of a website or application based on URL paths.