Creating a Kubernetes Ingress resource for GCP/GKE by example

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

apiVersion: extensions/v1beta1kind: Ingressmetadata:  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-ingressspec:  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?