marcduiker · LuiseFreese · Aug 12, 2021 · Aug 12, 2021 · Aug 12, 2021 · Aug 16, 2021
diff --git a/lessons/PowerShell/managed-identity-powershell.md b/lessons/PowerShell/managed-identity-powershell.md
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+# Managed Identity (PowerShell)
+
+Watch the recording of this lesson [on YouTube]().
+
+## Goal 🎯
+
+The goal of this lesson is to understand how you can create and use a system assigned managed identity to call an Azure Function in order to obtain a Microsoft Graph access token with the right permission scope. Microsoft Graph is THE API for all things Microsoft 365. 
+
+This lessons consists of the following exercises:
+
+|Nr|Exercise
+|-|-
+|0|[Prerequisites](#0-prerequisites)
+|1|[Create an Azure Functions](#1-create-an-azure-functions)
+|2|[Create Azure resources](#2-create-azure-resources)
+|3|[Create Managed Identity and assign permissions](#3-create-managed-identity-and-assign-permissions)
+|4|[Obtain an access token](#4-obtain-an-access-token)
+|5|[Homework](#5-homework)
+|6|[More info](#6-more-info)
+
+> 📝 **Tip** - If you're stuck at any point you can have a look at the [source code](../../src/{language}/{topic}) in this repository.
+
+---
+
+## 0. Prerequisites
+
+| Prerequisite | Exercise
+| - | -
+
+See [PowerShell prerequisites](../prerequisites/prerequisites-powershell.md) for more details.
+
+## 1. Create an Azure Functions
-## 1. Create an Azure Functions
+## 1. Create an Azure Functions App
-## 1. Create an Azure Functions
+## 1. Create an Azure Functions App
+
+before we will deploy our app to Azure, we will develop it locally in Visual Studio Code. This comes with some great advantages such as 
+
+* we don’t need to adjust to ever changing UI in Azure portal
+* we can benefit from source control
+* we can collaborate with others
+
+### Steps
+
+1. Install the Core Tools package with `npm install -g azure-functions-core-tools@3 --unsafe-perm true`
+2. Install the [Azure Functions extension for VS Code](https://marketplace.visualstudio.com/items?itemName=ms-azuretools.vscode-azurefunctions)
+3. Select **New Project**
+4. Select a folder for your project
+5. Select a language – I will use PowerShell
+6. Select **HTTP trigger** as a template
+7. Type in a better name like `GetGraphToken`
+8. Select Authorization level **Function**
+9. Select how you want to open your project – I prefer **Add to workspace**
+10. Open `run.ps1`
+11. Replace the default code by this: 
+
+```
-```
+```powershell
-```
+```powershell
+using namespace System.Net
+
+# Input bindings are passed in via param block
+param($Request, $TriggerMetadata)
+
+# Write to the Azure Functions log stream.
+Write-Host "PowerShell HTTP trigger function processed a request."
+
+# Interact with query parameters or the body of the request
+.$Scope = $Request.Query.Scope
+if (-not $Scope) {
+    $Scope = $Request.Body.Scope
+}
+#If parameter "Scope" has not been provided, we assume that graph.microsoft.com is the target resource
+If (!$Scope) {
+    $Scope = "https://graph.microsoft.com/"
+}
+
+$tokenAuthUri = $env:IDENTITY_ENDPOINT + "?resource=$Scope&api-version=2019-08-01"
+$response = Invoke-RestMethod -Method Get -Headers @{"X-IDENTITY-HEADER"="$env:IDENTITY_HEADER"} -Uri $tokenAuthUri -UseBasicParsing
+
+$accessToken = $response.access_token
+
+#Invoke REST call to Graph API
+$uri = 'https://graph.microsoft.com/v1.0/groups'
+$authHeader = @{    
+'Content-Type'='application/json'
+'Authorization'='Bearer ' +  $accessToken
+}
+
+$result = (Invoke-RestMethod -Uri $uri -Headers $authHeader -Method Get -ResponseHeadersVariable RES).value
+
+If ($result) {
+    $body = $result
+    $StatusCode = '200'
+}
+Else {
+    $body = $RES
+    $StatusCode = '400'}
+
+# Associate values to output bindings by calling 'Push-OutputBinding'
+Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
+    StatusCode = $StatusCode
+    Body = $body
+})
+```
+> 📝 **Tip** - Watch out – the Graph API will this way return up to 100 groups – Please adjust with query parameters as needed like `https://graph.microsoft.com/v1.0/groups?$top=42` or use pagination, which is described here: [Paging Microsoft Graph data in your app](https://docs.microsoft.com/en-us/graph/paging)
+
+Take a moment to understand what the code does: 
+
+* log that a request was received
+* define the scope (if not stated, it’s Microsoft Graph)
+* obtain the token from the environment variables IDENTITY_ENDPOINT and IDENTITY_HEADER (more about that in the next step!)
+* pass that token in the header of the REST call towards the group endpoint of Microsoft Graph
+* get the status code (hopefully 200) 🤞
+
+## 2. Create Azure resources
+
+Now we want to create all resources that we need in Azure: 
+
+For testing purposes, I pseudo-randomized a number to not always need to come up with new names:
+
+```
+#Get a random number between 100 and 300 to more easily be able to distinguish between several trials
+$rand = Get-Random -Minimum 100 -Maximum 300
+```
+We will now set some variables, this reduces risk of typos and makes our code better readable – also we can reuse it better – this is a courtesy to future-self
+```
+#Set values
+$resourceGroup = "DemoPlay$rand"
+$location = "westeurope"
+$storage = "luisedemostorage$rand"
+$functionapp = "LuiseDemo-functionapp$rand"
+
+```
+Let’s create a resource-group that will later hold our Azure Functions App
+```
+#create group
+az group create -n $resourceGroup -l $location
+```
+
+As our Functions App will need a storage account, we will create this as well:
+
+```
+#create storage account
+az storage account create `
+  -n $storage `
+  -l $location `
+  -g $resourceGroup `
+  --sku Standard_LRS
+```
+Now create the Azure Functions App which later holds our function (remember we created that earlier locally, but will later deploy it to Azure)
+
+```
+#create function
+az functionapp create `
+  -n $functionapp `
+  --storage-account $storage `
+  --consumption-plan-location $location `
+  --runtime powershell `
+  -g $resourceGroup `
+  --functions-version 3
+```
+
+> 🔎 **Observation** - < It will take a few moments for everything to be set, once this step is completed, you will be prompted with a message, that you also can benefit from Application Insights. >
+
+## 3. Create Managed Identity and assign permissions
+
+We want things to be super secure – this is why we want to enable a system assigned Managed Identity for our new function:
+
+### Steps
+
+```
-```
+```console
-```
+```console
+az functionapp identity assign -n $functionapp -g $resourceGroup
+```
+Our Managed Identity shall have the right permission scope to access Graph API for Group.Read.All, and to eventually be able to make the required REST call, we will need
+
+- the Graph API service Provider
+- permission scope, expressed as App role
+Let’s do this:
+
+```
-```
+```powershell
-```
+```powershell
+#Get Graph Api service provider (that's later needed for --api) 
+az ad sp list --query "[?appDisplayName=='Microsoft Graph'].{Name:appDisplayName, Id:appId}" --output table --all
+#Save that service provider 
+$graphId = az ad sp list --query "[?appDisplayName=='Microsoft Graph'].appId | [0]" --all 
+# Get permission scope for "Group.Read.All"
+$appRoleId = az ad sp show --id $graphId --query "appRoles[?value=='Group.Read.All'].id | [0]" 
+```
+Time to make the REST call to assign the permissions as shown above to the Managed Identity:
+```
-```
+```powershell
-```
+```powershell
+#Set values
+$webAppName="LuiseDemo-functionapp$rand"
+$principalId=$(az resource list -n $webAppName --query [*].identity.principalId --out tsv)
+$graphResourceId=$(az ad sp list --display-name "Microsoft Graph" --query [0].objectId --out tsv)
+$appRoleId=$(az ad sp list --display-name "Microsoft Graph" --query "[0].appRoles[?value=='Group.Read.All' && contains(allowedMemberTypes, 'Application')].id" --out tsv)
+$body="{'principalId':'$principalId','resourceId':'$graphResourceId','appRoleId':'$appRoleId'}"
+
+#the actual REST call 
+az rest --method post --uri https://graph.microsoft.com/v1.0/servicePrincipals/$principalId/appRoleAssignments --body $body --headers Content-Type=application/json
+```
+
+> 📝 **Tip** - < you may control if everything worked as intended in Azure portal: Azure Active Directory --> Enterprise applications --> Managed Identity
+
+> 🔎 **Observation** - < OBSERVATION >
+
+> ❔ **Question** - < how would you several permissions in one go? >
+
+To see things work, we will need to deploy our function into our Functions App. 
+
+1. head over to Visual Studio Code again
+2. select **deploy to Functions App** 
+3. Select the Functions App yuou already created
+4. Confirm the Pop up window by selecting **Deploy**
+
+> 🔎 **Observation** - < this might take a minute >
+
+<!-- check with Marc if I need to explain how to test in Azure portal -->
+
+## 4. Obtain an access token
+
+In this step we want to learn how we could ontain an access token which we needed for a successful HTTP request against Microsoft Graph API: 
+
+### Steps
+
+1. Although we would usually load an authentication library such as Azure.Identity and then  to obtain a token, there is an easier, but not documented way get the token in an Azure  Functions: Following and extrapolating [Obtain tokens for Azure resources](https://docs.microsoft.com/en-us/azure/app-service/overview-managed-identity?tabs=powershell#obtain-tokens-for-azure-resources) to Microsoft Graph surprisingly works: 
+
+```
+$resourceURI = "https://<AAD-resource-URI-for-resource-to-obtain-token>"
+$tokenAuthURI = $env:IDENTITY_ENDPOINT + "?resource=$resourceURI&api-version=2019-08-01"
+$tokenResponse = Invoke-RestMethod -Method Get -Headers @{"X-IDENTITY-HEADER"="$env:IDENTITY_HEADER"} -Uri $tokenAuthURI
+$accessToken = $tokenResponse.access_token
+```
+
+2. have a look at your **IDENTITY_ENDPOINT** and **IDENTITY_HEADER** environment variables at `https://<your-functionappname-here>.scm.azurewebsites.net/ENV.cshtml#envVariables`
+
+## 5. Homework
+
+<!-- check with Marc what would be appropriate homework -->
+
+## 6. More info
+<!-- 
+check with Marc about what should go in this section -->
+
+---
+[🔼 Lessons Index](../../README.md)
diff --git a/lessons/_lesson_template.md b/lessons/_lesson_template.md