Add AKS guide for testing Kubernetes support (#259)

Co-authored-by: Casper da Costa-Luis <casper.dcl@physics.org>

Author: 0x2b3bfa0

docs/guides/testing-kubernetes.md

@@ -0,0 +1,76 @@
+---
+page_title: Azure Kubernetes Service
+subcategory: Development
+---
+
+# Azure Kubernetes Service
+
+## Installing the Azure command-line interface tool
+
+Install the `az` tool following the official documentation on the Microsoft documentation portal: [https://docs.microsoft.com/en-us/cli/azure/install-azure-cli](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli)
+
+## Enabling experimental features
+
+In order to automatically provision GPU nodes for the cluster, enable the following experimental features through the `aks-preview` extension:
+
+```bash
+az extension add --name aks-preview
+az provider register --namespace Microsoft.ContainerService
+az feature register \
+  --namespace Microsoft.ContainerService \
+  --name GPUDedicatedVHDPreview
+```
+
+## Creating a test cluster
+
+The following commands will create an AKS cluster with a single node, keeping everything in a new resource group for easier deletion when done:
+
+```bash
+az group create \
+  --name testKubernetesResourceGroup \
+  --location eastus
+```
+
+```bash
+az aks create \
+  --resource-group testKubernetesResourceGroup \
+  --name testKubernetesCluster \
+  --node-vm-size Standard_NC6 \
+  --node-count 1 \
+  --aks-custom-headers UseGPUDedicatedVHD=true
+```
+
+<details><summary><i>Click to reveal a budget-friendly cluster configuration without GPU...</summary>
+
+```bash
+az aks create \
+  --resource-group testKubernetesResourceGroup \
+  --name testKubernetesCluster \
+  --node-vm-size Standard_A2_v2 \
+  --node-count 1
+```
+
+</details>
+
+## Retrieving the credentials
+
+Azure has some wrappers for Kubernetes authentication, and can generate the required credentials. The following command will produce a full-fledged `kubeconfig` string that can be directly stored in a `KUBERNETES_CONFIGURATION` CI/CD environment secret:
+
+```bash
+az aks get-credentials \
+  --resource-group testKubernetesResourceGroup \
+  --name testKubernetesCluster \
+  --file -
+```
+
+-> **Note:** Omitting the `--file -` option causes settings to be stored in the local computer's `~/.kube/config` file (which is automatically used by `kubectl` should you ever need to run a manual sanity check on the cluster).
+
+## Deleting the test cluster
+
+Once you've finished testing you can run the following command to delete the entire resource group (including the cluster and all its nodes):
+
+```bash
+az group delete --name testKubernetesResourceGroup
+```
+
+~> **Warning:** Try to delete the entire resource group as soon as you finish using the cluster to avoid unnecessary expenses. 🔥💵