test(mc): initial multicloud IaC boilerplate GKE, AKS, Kind (#1268)

# Description

Initial work on multi-cloud

* create modules for aks, gke, kind and retina
* use gcloud, azure, kind and helm providers
* create examples on how to use each module
* create automated tests in Go Terratest for each module example (only
initial work, since we require creds for public clouds)
* create integration test retina-kind (this can also be used as an
example for AKS, GKE and eventually EKS)
* create a Makefile for this subproject
* create GH workflow with automated tests


![diagram](https://github.com/user-attachments/assets/38ded8ec-0c31-4e5d-9bd0-8729115cf5b3)

## Related Issue

#1267 

## Checklist

- [x] I have read the [contributing
documentation](https://retina.sh/docs/contributing).
- [x] I signed and signed-off the commits (`git commit -S -s ...`). See
[this
documentation](https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification)
on signing commits.
- [x] I have correctly attributed the author(s) of the code.
- [x] I have tested the changes locally.
- [x] I have followed the project's style guidelines.
- [x] I have updated the documentation, if necessary.
- [x] I have added tests, if applicable.

## Screenshots (if applicable) or Testing Completed

All modules were tested and work as expected.

![Screenshot 2025-01-24 at 12 18
55](https://github.com/user-attachments/assets/2d222a13-2b12-4a11-a001-1b03a254e152)

See automated tests here
https://github.com/microsoft/retina/actions/runs/12993893617/job/36237118572


![image](https://github.com/user-attachments/assets/edafa98b-1d5d-44b0-a393-1bf7b7b70bda)



## Additional Notes

Add any additional notes or context about the pull request here.

---

Please refer to the [CONTRIBUTING.md](../CONTRIBUTING.md) file for more
information on how to contribute to this project.

.github/workflows/test-multicloud.yml

@@ -0,0 +1,31 @@
+name: Test Multicloud
+
+on:
+  pull_request:
+    paths:
+      - 'test/multicloud/**'
+
+jobs:
+  multicloud-test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: opentofu/setup-opentofu@v1
+      with:
+        tofu_version: 1.8.3
+
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Set up Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: '1.23'
+
+    - name: Install dependencies
+      run: go mod download
+      working-directory: test/multicloud/
+
+    - name: Run tests
+      run: make test
+      working-directory: test/multicloud/

test/multicloud/.gitignore

@@ -0,0 +1,6 @@
+terraform.tfvars
+.terraform
+terraform.tfstate
+*terraform.tfstate.*
+service-key.json
+*-kind-config

test/multicloud/Makefile

@@ -0,0 +1,42 @@
+PREFIX ?= retina
+STACK_NAME ?= $(PREFIX)-aks
+
+.PHONY: init plan apply quick gke aks kind destroy clean kind-kubeconfig test
+
+plan:
+	cd live/$(STACK_NAME) && \
+		tofu fmt && tofu init && tofu plan
+
+apply:
+	cd live/$(STACK_NAME) && \
+		tofu apply --auto-approve
+
+quick:
+	@make plan
+	@make apply
+
+gke: export STACK_NAME=$(PREFIX)-gke
+gke:
+	@make quick
+
+aks: export STACK_NAME=$(PREFIX)-aks
+aks:
+	@make quick
+
+kind: export STACK_NAME=$(PREFIX)-kind
+kind:
+	@make quick
+
+destroy:
+	cd live/$(STACK_NAME) && \
+		tofu destroy --auto-approve
+
+clean: destroy
+	@cd live/$(STACK_NAME) && \
+		rm -rf .terraform && rm terraform.tfstate && rm terraform.tfstate.backup
+
+kind-kubeconfig:
+	@kubectl config set-context live/$(PREFIX)-kind/mc-kind-config
+
+test:
+	@cd test && go test -v -count=1 -timeout 30m ./...

test/multicloud/README.md

@@ -0,0 +1,98 @@
+# Multi Cloud Retina
+
+This project leverages [OpenTofu](https://opentofu.org/docs/intro/) Infrastructure as Code (IaC) to create Kubernetes infrastructure on multi-cloud and deploy [microsoft/retina](https://github.com/microsoft/retina) via Helm provider.
+
+![Architecture Diagram](./diagrams/diagram.svg)
+
+## Modules available
+
+* [aks](./modules/aks/)
+* [gke](./modules/gke/)
+* [kind](./modules/kind/)
+* [retina](./modules/retina/)
+
+## Prerequisites
+
+* [OpenTofu installation guide](https://opentofu.org/docs/intro/install/)
+
+* AKS:
+
+    1. create an Azure account
+    2. [Install az](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli)
+
+    To deploy an AKS cluster and install retina, create file `live/retina-aks/terraform.tfvars` with the Azure TenantID and SubscriptionID
+
+    ```sh
+    # example values
+    subscription_id     = "d6050d84-e4dd-463d-afc7-a6ab3dc33ab7"
+    tenant_id           = "ac8a4ccd-35f1-4f95-a688-f68e3d89adfc"
+    ```
+
+* GKE:
+
+    1. create a gcloud account, project and enable billing
+    2. create a service account and service account key
+    3. [Enable Kubernetes Engine API](https://console.developers.google.com/apis/api/container.googleapis.com/overview?project=mc-retina)
+    4. [Install gcloud](https://cloud.google.com/sdk/docs/install)
+
+    To deploy a GKE cluster export `GOOGLE_APPLICATION_CREDENTIALS` env variable to point to the path where your [service account key](https://cloud.google.com/iam/docs/keys-create-delete) is located.
+
+    ```sh
+    # example
+    export GOOGLE_APPLICATION_CREDENTIALS=/Users/srodi/src/retina/test/multicloud/live/retina-gke/service-key.json
+    ```
+
+* Kind:
+
+    1. Docker installed on the host machine
+
+## Quickstart
+
+The following Make targets can be used to manage each stack lifecycle.
+
+### Create
+
+Format code, initialize OpenTofu, plan and apply the stack to create infra and deploy retina
+
+* AKS:
+
+    ```sh
+    make aks
+    ```
+
+* GKE:
+
+    ```sh
+    make gke
+    ```
+
+* Kind:
+
+    ```sh
+    make kind
+    ```
+
+### Clean up
+
+To destroy the cluster specify the `STACK_NAME` and run `make clean`.
+
+```sh
+# destroy AKS and cleanup local state files
+# set a different stack as needed (i.e. retina-gke, retina-kind)
+export STACK_NAME=retina-aks
+make clean
+```
+
+### Test
+
+The test framework is levergaing Go and [Terratest](https://terratest.gruntwork.io/docs/). To run tests:
+
+```sh
+make test
+```
+
+## Providers references
+
+* [GKE resource documentation](https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/container_cluster)
+* [AKS resource documentation](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/kubernetes_cluster)
+* [Kind resource documentation](https://registry.terraform.io/providers/tehcyx/kind/latest/docs/resources/cluster)