AWS ALB Ingress Advanced Request Routing

AWS Application Load Balancer allows traffic to be routed based on HTTP header, HTTP request method, query string, source IP, in addition host and path-based routing.

As it turns out, configuring a k8s ingress can be a bit tricky, as the Official documentations does not provide good examples. In my example, I will show how to route requests with the host header “my-host.example.com” and the HTTP header “X-Custom-Header: CustomHeaderValue” to the Kubernetes service “my-srv” on port 8080.

Prepare ingress k8s manifest

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-srv-custom-header
  annotations:
    alb.ingress.kubernetes.io/conditions.header-based: |
      [{"field":"http-header","httpHeaderConfig":{"httpHeaderName": "X-Custom-Header", "values":["CustomHeaderValue"]}}]
    alb.ingress.kubernetes.io/actions.header-based: |
      {"type":"forward","forwardConfig":{"targetGroups":[{"serviceName":"my-srv","servicePort":8080}]}}
    alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:eu-central-1:1111111111:certificate/528f4790-1d24-xxxx-xxxx-a8f493a3c948
    alb.ingress.kubernetes.io/scheme: internet-facing
    alb.ingress.kubernetes.io/target-type: ip
spec:
  ingressClassName: alb
  rules:
    - host: "my-host.example.com"
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: header-based
                port:
                  name: use-annotation

Verification

$ curl -H 'X-Custom-Header: CustomHeaderValue' https://my-host.example.com/healthcheck
OK

# no header
$ curl https://my-host.example.com/healthcheck
Backend service does not exists