Observations about spam signups

Using Ghost
60

This is an excellent solution for my case, I’m using Ghost on Kubernetes with Traefik v3 deployed with Helm. Using qwen v3 I’ve adapted and tested your approach successfully.

Prompt:

generate a kubernetes manifest equivalent for this traefik v3 middleware:

- "traefik.http.middlewares.signup-ratelimit.ratelimit.average=2"
(...the rest of your config)

Response (tested and working):

To translate Traefik v3 static configuration (labels/flags) into Kubernetes manifests, we need to leverage the Traefik CRDs (Custom Resource Definitions). In a K8s environment, we decouple the middleware definition from the router definition, then reference them via an IngressRoute (or standard Ingress with annotations, though CRDs are preferred for v3 features like precise priority and middleware chaining).

Here is the breakdown of the logic:

  1. Middleware: Define a Middleware CRD with the rate-limiting spec.
  2. Service: Ensure the ghost service exists (I will provide a placeholder).
  3. Router: Define an IngressRoute that matches the Host, Path, and Method, applies the middleware, and sets the priority.

1. The Middleware CRD (ratelimit-middleware.yaml)

This defines the signup-ratelimit middleware. Note that Traefik’s rate limit uses a token bucket algorithm.

  • average: 2 requests per period.
  • period: 1 hour.
  • burst: 3 requests allowed above the average.
apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: signup-ratelimit
  namespace: default # Adjust to your target namespace
spec:
  rateLimit:
    average: 2
    period: "1h"
    burst: 3

2. The IngressRoute CRD (ghost-ingressroute.yaml)

This replaces the router configuration. It explicitly handles the Host, Path, and Method matching, and assigns the priority.

apiVersion: traefik.io/v1alpha1
kind: IngressRoute
metadata:
  name: ghost-signup
  namespace: default # Adjust to your target namespace
spec:
  entryPoints:
    - websecure # Assuming HTTPS; use 'web' for HTTP if needed
  routes:
    - match: Host(`yourdomain.com`) && Path(`/members/api/send-magic-link/`) && Method(`POST`)
      kind: Rule
      priority: 100
      middlewares:
        - name: signup-ratelimit
          namespace: default # Must match the namespace of the Middleware CRD
      services:
        - name: ghost
          port: 80 # Adjust to the actual port exposed by your Ghost service

3. The Service Placeholder (ghost-service.yaml)

For completeness, here is how the ghost service might look. Ensure this matches your actual deployment.

apiVersion: v1
kind: Service
metadata:
  name: ghost
  namespace: default
spec:
  selector:
    app: ghost # Ensure this matches your Deployment labels
  ports:
    - protocol: TCP
      port: 80
      targetPort: 2368 # Default Ghost port

Key Considerations & SRE Notes

1. CRD Installation

Ensure you have the Traefik CRDs installed in your cluster. If you installed Traefik via Helm, this is usually default. If not, apply them from the official repo:

kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.0/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

2. Namespace Scope

Traefik Middlewares are namespaced resources.

  • If your IngressRoute and Middleware are in the same namespace, you can omit the namespace field in the middlewares reference.
  • If they are in different namespaces, you must specify the namespace in the IngressRoute middleware reference, and ensure Traefik is configured to watch cross-namespace resources (via providers.kubernetesCRD.allowCrossNamespace in Traefik’s static config).

3. Rate Limiting Logic Check

  • Current Config: 2 requests/hour with a burst of 3.
  • Implication: This is extremely restrictive. It allows a burst of 3 requests immediately, then throttles to ~1 request every 30 minutes.
  • SRE Recommendation: For a “send magic link” endpoint, this might be too aggressive for legitimate users who might click “resend” quickly. Consider if average=10 and period=1m (10 requests per minute) might offer better UX while still preventing abuse. Monitor the traefik_middleware_reject_total metric to tune this.

4. Alternative: Standard Kubernetes Ingress

If you prefer not to use IngressRoute CRDs, you can use standard Ingress with annotations, but priority and method matching are harder to express cleanly in v3 without CRDs. The annotation approach would look like this (less recommended for complex rules):

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ghost-signup
  annotations:
    traefik.ingress.kubernetes.io/router.middlewares: default-signup-ratelimit@kubernetescrd
    traefik.ingress.kubernetes.io/router.priority: "100"
    # Note: Method matching and complex path rules are limited in standard Ingress
spec:
  rules:
    - host: yourdomain.com
      http:
        paths:
          - path: /members/api/send-magic-link/
            pathType: Exact
            backend:
              service:
                name: ghost
                port:
                  number: 80

Warning: Standard Ingress does not natively support Method(POST) filtering in Traefik without additional middleware or regex hacks on the path. The IngressRoute CRD is the superior choice here.

Verification Steps

  1. Apply the Middleware: kubectl apply -f ratelimit-middleware.yaml
  2. Apply the IngressRoute: kubectl apply -f ghost-ingressroute.yaml
  3. Check Traefik Dashboard or logs to confirm the route is loaded.
  4. Test with curl:
    # Should succeed (within burst)
curl -X POST https://yourdomain.com/members/api/send-magic-link/

# Should fail with 429 Too Many Requests after exceeding burst/rate

Evidence: