Add doc for AKS integration (#3206)

* add doc for AKS integration

Signed-off-by: dejanualex <dejanualexandru@gmail.com>

* remove merge action and outputs

Signed-off-by: dejanualex <dejanualexandru@gmail.com>

---------

Signed-off-by: dejanualex <dejanualexandru@gmail.com>
Co-authored-by: Kim Christensen <2461567+kichristensen@users.noreply.github.com>

docs/content/docs/integrations/aks.md

@@ -4,4 +4,155 @@ description: How to connect to an AKS cluster inside a Porter bundle.
 weight: 1
 ---
 
-## Coming Soon
+* AKS cluster authentication requires more than just a kubeconfig.
+
+### Prerequisites
+
+* To access resources that are secured by a Microsoft Entra tenant, the entity that requires access must be represented by a security principal. This requirement is true for both users (user principal) and applications (service principal). 
+
+* Furthermore, the following will be used:
+  * A **service principal** which is the local representation of an application object in a single Microsoft Entra tenant. 
+  * A **client secret** used for authenticating with the service principal.
+
+* You can either create a new service principal (az cli guide [here](https://learn.microsoft.com/en-us/cli/azure/ad/sp?view=azure-cli-latest#az-ad-sp-create)) or use an existing one.
+
+* From Azure portal: Microsoft Entra admin center (under App registrations) select your application and get: `Application (client) ID`, `Object ID`, `Directory (tenant) ID` and set them as env variables.
+
+```bash
+export AZURE_CLIENT_ID="insert_ApplicationID"
+export AZURE_TENANT_ID="insert_TenantID"
+export AZURE_CLIENT_SECRET="insert_SecretValue"
+export AZURE_SUBSCRIPTION_ID="insert_SubscriptionID"
+```
+
+### Bundle setup
+
+* After the variables have been set, create a credentials set, by saving the following json to a file e.g. `aks_creds.json` and apply the file: `porter credentials apply aks_creds.json`
+
+```json
+{
+    "schemaType": "CredentialSet",
+    "schemaVersion": "1.0.1",
+    "name": "akscreds",
+    "namespace": "",
+    "credentials": [
+
+        {
+            "name": "azure_client_id",
+            "source": {
+                "env": "AZURE_CLIENT_ID"
+            }
+        },
+
+        {
+            "name": "azure_client_secret",
+            "source": {
+                "env": "AZURE_CLIENT_SECRET"
+            }
+        },
+
+        {
+            "name": "azure_subscription_id",
+            "source": {
+                "env": "AZURE_SUBSCRIPTION_ID"
+            }
+        },
+
+        {
+            "name": "azure_tenant_id",
+            "source": {
+                "env": "AZURE_TENANT_ID"
+            }
+        }
+    ]
+}
+```
+
+* Verify that `akscreds` credentials set exists: `porter credentials list`
+
+* Install [az mixin](https://porter.sh/mixins/az/) and declare the credentials in the bundle manifest:
+
+```yaml
+credentials:
+- name: azure_client_id
+  env: AZURE_CLIENT_ID
+  description: AAD Client ID for Azure account authentication - used for AKS Cluster SPN details and for authentication to azure to get KubeConfig
+- name: azure_tenant_id
+  env: AZURE_TENANT_ID
+  description: Azure AAD Tenant Id for Azure account authentication - used to authenticate to Azure to get KubeConfig 
+- name: azure_client_secret
+  env: AZURE_CLIENT_SECRET
+  description: AAD Client Secret for Azure account authentication - used for AKS Cluster SPN details and for authentication to azure to get KubeConfig
+- name: azure_subscription_id
+  env: AZURE_SUBSCRIPTION_ID
+  description: Azure Subscription Id used to set the subscription where the account has access to multiple subscriptions
+```
+
+* Declare Azure resource group and AKS name as parameters:
+```yaml
+parameters:
+  - name: rg_name
+    type: string
+    description: "Resource group in which AKS resides"
+    default: "demorg"
+    applyTo:
+      - merge
+
+  - name: aks_name
+    type: string
+    description: "AKS name"
+    default: "demoaks"
+    applyTo:
+      - merge
+```
+
+* An example of the `install` action that integrates with AKS and utilizes [Kubernetes mixin](https://porter.sh/design/kubernetes-mixin/) to deploy a pod to the cluster, based on the `cnab/app/nginx` manifest:
+
+```bash
+install:
+  - az:
+      description: "Azure CLI login"
+      arguments:
+        - login
+      flags:
+        service-principal:
+        username: ${ bundle.credentials.azure_client_id }
+        password: ${ bundle.credentials.azure_client_secret }
+        tenant: ${ bundle.credentials.azure_tenant_id }
+
+  - az:
+      description: "Azure set subscription Id"
+      arguments:
+        - "account"
+        - "set"
+      flags:
+        subscription: ${ bundle.credentials.azure_subscription_id }
+  
+  - az:
+      description: "Get access creds for AKS"
+      arguments:
+        - "aks"
+        - "get-credentials"
+      flags:
+        resource-group: ${ bundle.parameters.rg_name }
+        name: ${ bundle.parameters.aks_name }
+  
+  - kubernetes:
+      description: "Deploy nginx pod"
+      manifests:
+        - cnab/app/nginx
+      wait: true
+      surpress-output: false
+      outputs:
+        - name: pod_name
+          resourceType: "pod"
+          resourceName: "basic-nginx"
+          namespace: "default"
+          jsonPath: "metadata.name"
+```
+
+* Bundle usage: 
+
+```bash
+porter install -c akscreds --param rg_name=<RESOURCE_GROUP_NAME> --param aks_name=<AKS_NAME>
+```