add keycloak to k8s for ingress nginx

[indiepopart]

Add Keycloak prod deployment to k8s sub-generator for ingress nginx edge option, including PostgreSQL database and clustering. HTTPS/TLS is not configured. This allows testing on minikube.

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[mraible]

I've been testing this for the last couple of days and can't get it to work on macOS. I was able to get everything to start on my M1, but I had to build M1-compatible images and deploy those to Docker Hub.

We should change the commands that are output to the console for deploying directly since they don't currently contain -PjibArchitecture=arm64. For example:

./gradlew -Pprod bootJar jib -PjibArchitecture=arm64 -Djib.to.image=mraible/gateway

I've been talking with @indiepopart and ideally, this should work after installing this branch:

First, start Minikube and enable ingress:

minikube start --cpus 6
minikube addons enable ingress
minikube ip

You will need to use the output of minikube ip + .nip.io when prompted. For example, 192.168.58.2.nip.io.

Then, create a microservices stack and run the k8s sub-generator:

take reactive-stack
jhipster jdl reactive-mf
# Deploy images to Docker Hub
rm -rf kubernetes
take k8s
jhipster k8s # choose Ingress and NGINX
./kubectl-apply.sh -f

[mraible]

@indiepopart I think we need to document a couple of things for this PR and Minikube:

1. That you need to run minikube addons enable ingress.
2. That it won't work on macOS or Windows. Minikube IP is not externally accessible via Ingress/ Nodeport Servce kubernetes/minikube#13951

The best place to add documentation for Minikube is probably https://www.jhipster.tech/kubernetes/. However, I'm not sure people will see it there, so outputting it to the console might be a good idea too.

[indiepopart]

I woud rather change the generator and documentation so it works for also for macOS or Windows. Avoid using the minikube ip and nip.io.

[indiepopart]

@mraible The README was updated with instructions to use minikube tunnel for exposing the ingress controller to the host. The deployment was only verified on Linux.