I'm trying to make sense of an example Kubernetes YAML config file that I am trying to customize:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-web-server
  namespace: myapp
  annotations:
    kubernetes.io/ingress.class: alb
    alb.ingress.kubernetes.io/scheme: internal
    alb.ingress.kubernetes.io/security-groups: my-sec-group
    app.kubernetes.io/name: my-alb-ingress-web-server
    app.kubernetes.io/component: my-alb-ingress
spec:
  rules:
    - http:
        paths:
          - path: /*
            backend:
              serviceName: my-web-server
              servicePort: 8080

The documentation for this example claims its for creating an "Ingress", or a K8s object that manages inbound traffic to a service or pod.

This particular Ingress resource appears to use AWS ALB (Application Load Balancers) and I need to adapt it to create and Ingress resource in GCP/GKE.

I'm Googling the Kubernetes documentation high and low and although I found the kubernetes.io/ingress.class docs I don't see where they define "alb" as a valid value for this property. I'm asking because I obviously need to find the correct kubernetes.io/ingress.class value for GCP/GKE and I assume if I can find the K8s/AWS Ingress documentation I should be able to find the K8s/GCP Ingress documentation.

I'm assuming K8s has AWS, GCP, Azure, etc. built-in client to kubectl for connecting to these clouds/providers?

So I ask: how does the above configuration tell K8s that we are creating an AWS Ingress (as opposed to an Azure Ingress, GCP Ingress, etc.) and where is the documentation for this?