NGINX Ingress CORS Annotations Not Applied

You encounter a nginx configuration issue that prevents your workflow from completing. This guide walks through the fix step by step.

Wrong ❌

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/enable-cors: "true"
    nginx.ingress.kubernetes.io/cors-allow-methods: "GET, POST"
    # Missing cors-allow-origin

Wrong Output

CORS headers not present. Browser preflight fails. cors-allow-origin required.

Right ✅

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/enable-cors: "true"
    nginx.ingress.kubernetes.io/cors-allow-origin: "https://app.example.com"
    nginx.ingress.kubernetes.io/cors-allow-methods: "GET, POST, PUT, DELETE, OPTIONS"
    nginx.ingress.kubernetes.io/cors-allow-headers: "Authorization, Content-Type"
    nginx.ingress.kubernetes.io/cors-allow-credentials: "true"

Right Output

CORS headers present: Access-Control-Allow-Origin: https://app.example.com. Preflight passes.

Prevention

• cors-allow-origin is required when enable-cors is true.
• Include OPTIONS in cors-allow-methods for preflight.
• Set cors-allow-headers for custom headers.
• Use cors-allow-credentials for cookies/auth.
• Test with curl -H 'Origin: https://app.example.com' -I.

DodaTech applies similar defensive patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro infrastructure for production reliability.

Common Mistakes with ingress cors annotations

1. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors
2. Non-exhaustive pattern matches that compile with warnings then crash at runtime
3. Misunderstanding that String is [Char] with poor performance for large text operations

These mistakes appear frequently in real-world NGINX code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

This quick fix is part of the DodaTech infrastructure engineering series. Learn more at DodaTech tutorials.