Kubernetes Ingress 404 Not Found Fix

In this tutorial, you'll learn about Kubernetes Ingress 404 Not Found Fix. We cover key concepts, practical examples, and best practices.

The Problem

You visit your application's URL and get a 404 Not Found:

$ curl https://app.example.com
404 Not Found

The Ingress resource exists, the service and pods are running, but traffic is not reaching the backend. The ingress controller either cannot find the service or the path does not match.

Quick Fix

Step 1: Check the ingress controller is running

kubectl get pods -n ingress-nginx

NAME                                        READY   STATUS    RESTARTS
ingress-nginx-controller-7d6c9b5d8f-abc12   1/1     Running   0

If no ingress controller is deployed, the Ingress resource does nothing:

# Install NGINX Ingress Controller
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/main/deploy/static/provider/cloud/deploy.yaml

Step 2: Verify the ingress rule matches a real service

kubectl describe ingress my-ingress

Rules:
  Host        Path  Backends
  ----        ----  --------
  app.example.com
              /api    my-service:8080 (10.1.0.5:8080)

WRONG -- service name does not exist:

rules:
- host: app.example.com
  http:
    paths:
    - path: /
      pathType: Prefix
      backend:
        service:
          name: my-srvc   # typo -- should be my-service
          port:
            number: 8080

RIGHT -- verify with kubectl get svc:

kubectl get svc my-service

Fix the ingress:

kubectl edit ingress my-ingress

Step 3: Check the service has endpoints

kubectl get endpoints my-service

NAME          ENDPOINTS           AGE
my-service    10.1.0.5:8080       2d

If ENDPOINTS is empty, the service selector does not match any pods:

kubectl describe svc my-service
# Selector: app=my-app
kubectl get pods -l app=my-app
# Check if pods have label "app: my-app"

Step 4: Test path matching

Ingress controllers use path matching rules. A prefix /api will not match a request to /api/v1/users with Exact pathType:

WRONG -- Exact pathType for API routes:

paths:
- path: /api
  pathType: Exact    # only matches /api exactly, not /api/v1

RIGHT -- Prefix pathType:

paths:
- path: /api
  pathType: Prefix   # matches /api, /api/v1, /api/v1/users

Step 5: Check TLS certificate configuration

A misconfigured TLS block causes 404 or SSL errors:

kubectl describe ingress my-ingress

TLS:
  hosts:
  - app.example.com
  secretName: my-tls-secret

WRONG -- secret does not exist:

tls:
- hosts:
  - app.example.com
  secretName: nonexistent-secret

RIGHT -- create the secret first:

kubectl create secret tls my-tls-secret \
  --cert=fullchain.pem \
  --key=privkey.pem

Or use cert-manager to auto-provision TLS certificates.

Step 6: Check ingress controller logs

kubectl logs -n ingress-nginx deployment/ingress-nginx-controller

Look for lines mentioning your host or service:

WARNING: service "default/my-service" does not have any active endpoints

Or check the controller's configuration dump:

kubectl exec -n ingress-nginx deployment/ingress-nginx-controller -- cat /etc/nginx/nginx.conf | grep my-service

Use DodaTech's Ingress Debugger to visualize the traffic path from external request through the ingress controller to the backend pods.

Prevention

• Always verify service names and ports match the Ingress spec.
• Use kubectl get endpoints after creating a service.
• Test with curl inside the cluster before enabling external access.
• Use pathType: Prefix for API routes unless you need exact matching.
• Set up monitoring on the ingress controller metrics.

Common Mistakes with ingress 404

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 K8S 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