Build Go apps with Microsoft Graph and app-only authentication

Article
Developer (Beginner)
19 minutes to complete

This tutorial teaches you how to build a Go console app that uses the Microsoft Graph API to access data using app-only authentication. App-only authentication is a good choice for background services or applications that need to access data for all users in an organization.

Note

To learn how to use Microsoft Graph to access data on behalf of a user, see this user (delegated) authentication tutorial.

In this tutorial, you will:

List users

Tip

As an alternative to following this tutorial, you can download or clone the GitHub repository and follow the instructions in the README to register an application and configure the project.

Prerequisites

Before you start this tutorial, you should have Go installed on your development machine.

You should also have a Microsoft work or school account with the Global administrator role. If you don't have a Microsoft 365 tenant, you might qualify for one through the Microsoft 365 Developer Program; for details, see the FAQ. Alternatively, you can sign up for a 1-month free trial or purchase a Microsoft 365 plan.

Note

This tutorial was written with Go version 1.19.3. The steps in this guide may work with other versions, but that has not been tested.

Register the app in the portal

18 minutes remaining

In this exercise you will register a new application in Azure Active Directory to enable app-only authentication. You can register an application using the Microsoft Entra admin center, or by using the Microsoft Graph PowerShell SDK.

Register application for app-only authentication

In this section you will register an application that supports app-only authentication using client credentials flow.

Microsoft Entra admin center
PowerShell

Open a browser and navigate to the Microsoft Entra admin center and login using a Global administrator account.
Select Microsoft Entra ID in the left-hand navigation, expand Identity, expand Applications, then select App registrations.
Select New registration. Enter a name for your application, for example, Graph App-Only Auth Tutorial.
Set Supported account types to Accounts in this organizational directory only.
Leave Redirect URI empty.
Select Register. On the application's Overview page, copy the value of the Application (client) ID and Directory (tenant) ID and save them, you will need these values in the next step.
Select API permissions under Manage.
Remove the default User.Read permission under Configured permissions by selecting the ellipses (...) in its row and selecting Remove permission.
Select Add a permission, then Microsoft Graph.
Select Application permissions.
Select User.Read.All, then select Add permissions.
Select Grant admin consent for..., then select Yes to provide admin consent for the selected permission.
Select Certificates and secrets under Manage, then select New client secret.
Enter a description, choose a duration, and select Add.
Copy the secret from the Value column, you will need it in the next steps.

Important

This client secret is never shown again, so make sure you copy it now.

To use PowerShell, you'll need the Microsoft Graph PowerShell SDK. If you do not have it, see Install the Microsoft Graph PowerShell SDK for installation instructions.

Create a new file named RegisterAppForAppOnlyAuth.ps1 and add the following code.

param(
  [Parameter(Mandatory=$true,
  HelpMessage="The friendly name of the app registration")]
  [String]
  $AppName,

  [Parameter(Mandatory=$true,
  HelpMessage="The application permission scopes to configure on the app registration")]
  [String[]]
  $GraphScopes,

  [Parameter(Mandatory=$false)]
  [Switch]
  $StayConnected = $false
)

$graphAppId = "00000003-0000-0000-c000-000000000000"

# Requires an admin
Connect-MgGraph -Scopes "Application.ReadWrite.All AppRoleAssignment.ReadWrite.All User.Read" -UseDeviceAuthentication -ErrorAction Stop

# Get context for access to tenant ID
$context = Get-MgContext -ErrorAction Stop
$authTenant = $context.TenantId

# Create app registration
$appRegistration = New-MgApplication -DisplayName $AppName -SignInAudience "AzureADMyOrg" -ErrorAction Stop
Write-Host -ForegroundColor Cyan "App registration created with app ID" $appRegistration.AppId

# Create corresponding service principal
$appServicePrincipal = New-MgServicePrincipal -AppId $appRegistration.AppId -ErrorAction SilentlyContinue `
  -ErrorVariable SPError
if ($SPError)
{
  Write-Host -ForegroundColor Red "A service principal for the app could not be created."
  Write-Host -ForegroundColor Red $SPError
  Exit
}

Write-Host -ForegroundColor Cyan "Service principal created"

# Lookup available Graph application permissions
$graphServicePrincipal = Get-MgServicePrincipal -Filter ("appId eq '" + $graphAppId + "'") -ErrorAction Stop
$graphAppPermissions = $graphServicePrincipal.AppRoles

$resourceAccess = @()

foreach($scope in $GraphScopes)
{
  $permission = $graphAppPermissions | Where-Object { $_.Value -eq $scope }
  if ($permission)
  {
    $resourceAccess += @{ Id =  $permission.Id; Type = "Role"}
  }
  else
  {
    Write-Host -ForegroundColor Red "Invalid scope:" $scope
    Exit
  }
}

# Add the permissions to required resource access
Update-MgApplication -ApplicationId $appRegistration.Id -RequiredResourceAccess `
 @{ ResourceAppId = $graphAppId; ResourceAccess = $resourceAccess } -ErrorAction Stop
Write-Host -ForegroundColor Cyan "Added application permissions to app registration"

# Add admin consent
foreach ($appRole in $resourceAccess)
{
  New-MgServicePrincipalAppRoleAssignment -ServicePrincipalId $appServicePrincipal.Id `
   -PrincipalId $appServicePrincipal.Id -ResourceId $graphServicePrincipal.Id `
   -AppRoleId $appRole.Id -ErrorAction SilentlyContinue -ErrorVariable SPError | Out-Null
  if ($SPError)
  {
    Write-Host -ForegroundColor Red "Admin consent for one of the requested scopes could not be added."
    Write-Host -ForegroundColor Red $SPError
    Exit
  }
}
Write-Host -ForegroundColor Cyan "Added admin consent"

# Add a client secret
$clientSecret = Add-MgApplicationPassword -ApplicationId $appRegistration.Id -PasswordCredential `
 @{ DisplayName = "Added by PowerShell" } -ErrorAction Stop

Write-Host
Write-Host -ForegroundColor Green "SUCCESS"
Write-Host -ForegroundColor Cyan -NoNewline "Client ID: "
Write-Host -ForegroundColor Yellow $appRegistration.AppId
Write-Host -ForegroundColor Cyan -NoNewline "Tenant ID: "
Write-Host -ForegroundColor Yellow $authTenant
Write-Host -ForegroundColor Cyan -NoNewline "Client secret: "
Write-Host -ForegroundColor Yellow $clientSecret.SecretText
Write-Host -ForegroundColor Cyan -NoNewline "Secret expires: "
Write-Host -ForegroundColor Yellow $clientSecret.EndDateTime

if ($StayConnected -eq $false)
{
  Disconnect-MgGraph | Out-Null
  Write-Host "Disconnected from Microsoft Graph"
}
else
{
  Write-Host
  Write-Host -ForegroundColor Yellow `
   "The connection to Microsoft Graph is still active. To disconnect, use Disconnect-MgGraph"
}

Save the file.
Open PowerShell and change the current directory to the location of RegisterAppForAppOnlyAuth.ps1.

Run the following command.

.\RegisterAppForAppOnlyAuth.ps1 -AppName "Graph App-Only Auth Tutorial" -GraphScopes "User.Read.All"

Follow the prompt to open https://microsoft.com/devicelogin in a browser, enter the provided code, and complete the authentication process.

Copy the Client ID, Tenant ID, and Client secret values from the script output. You will need these values in the next step.

SUCCESS
Client ID: ae2386e6-799e-4f75-b191-855d7e691c75
Tenant ID: 5927c10a-91bd-4408-9c70-c50bce922b71
Client secret: ...
Secret expires: 10/28/2024 5:01:45 PM

Note

Notice that, unlike the steps when registering for user authentication, in this section you did configure Microsoft Graph permissions on the app registration. This is because app-only auth uses the client credentials flow, which requires that permissions be configured on the app registration. See The .default scope for details.

Create a Go console app

15 minutes remaining

Begin by initializing a new Go module using the Go CLI. Open your command-line interface (CLI) in a directory where you want to create the project. Run the following command.

go mod init graphapponlytutorial

Install dependencies

Before moving on, add some additional dependencies that you will use later.

Azure Identity Client Module for Go to authenticate the user and acquire access tokens.
Microsoft Graph SDK for Go to make calls to the Microsoft Graph.
GoDotEnv for reading environment variables from .env files.

Run the following commands in your CLI to install the dependencies.

go get github.com/Azure/azure-sdk-for-go/sdk/azidentity
go get github.com/microsoftgraph/msgraph-sdk-go
go get github.com/joho/godotenv

Load application settings

In this section you'll add the details of your app registration to the project.

Create a file in the same directory as go.mod named .env and add the following code.

CLIENT_ID=YOUR_CLIENT_ID_HERE
CLIENT_SECRET=YOUR_CLIENT_SECRET_HERE
TENANT_ID=YOUR_TENANT_ID_HERE

Update the values according to the following table.

Setting Value

CLIENT_ID The client ID of your app registration

CLIENT_SECRET The client secret of your app registration

TENANT_ID The tenant ID of your organization

Tip

Optionally, you can set these values in a separate file named .env.local.

Setting	Value
`CLIENT_ID`	The client ID of your app registration
`CLIENT_SECRET`	The client secret of your app registration
`TENANT_ID`	The tenant ID of your organization

Design the app

In this section you will create a simple console-based menu.

Create a new directory in the same directory as go.mod named graphhelper.

Add a new file in the graphhelper directory named graphhelper.go and add the following code.

package graphhelper

import (
    "context"
    "os"

    "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
    auth "github.com/microsoft/kiota-authentication-azure-go"
    msgraphsdk "github.com/microsoftgraph/msgraph-sdk-go"
    "github.com/microsoftgraph/msgraph-sdk-go/models"
    "github.com/microsoftgraph/msgraph-sdk-go/users"
)

type GraphHelper struct {
    clientSecretCredential *azidentity.ClientSecretCredential
    appClient              *msgraphsdk.GraphServiceClient
}

func NewGraphHelper() *GraphHelper {
    g := &GraphHelper{}
    return g
}

This creates a basic GraphHelper type that you will extend in later sections to use Microsoft Graph.

Create a file in the same directory as go.mod named graphapponlytutorial.go. Add the following code.

package main

import (
    "fmt"
    "graphapponlytutorial/graphhelper"
    "log"

    "github.com/joho/godotenv"
)

func main() {
    fmt.Println("Go Graph App-Only Tutorial")
    fmt.Println()

    // Load .env files
    // .env.local takes precedence (if present)
    godotenv.Load(".env.local")
    err := godotenv.Load()
    if err != nil {
        log.Fatal("Error loading .env")
    }

    graphHelper := graphhelper.NewGraphHelper()

    initializeGraph(graphHelper)

    var choice int64 = -1

    for {
        fmt.Println("Please choose one of the following options:")
        fmt.Println("0. Exit")
        fmt.Println("1. Display access token")
        fmt.Println("2. List users")
        fmt.Println("3. Make a Graph call")

        _, err = fmt.Scanf("%d", &choice)
        if err != nil {
            choice = -1
        }

        switch choice {
        case 0:
            // Exit the program
            fmt.Println("Goodbye...")
        case 1:
            // Display access token
            displayAccessToken(graphHelper)
        case 2:
            // List users
            listUsers(graphHelper)
        case 3:
            // Run any Graph code
            makeGraphCall(graphHelper)
        default:
            fmt.Println("Invalid choice! Please try again.")
        }

        if choice == 0 {
            break
        }
    }
}

Add the following placeholder methods at the end of the file. You'll implement them in later steps.

func initializeGraph(graphHelper *graphhelper.GraphHelper) {
    // TODO
}

func displayAccessToken(graphHelper *graphhelper.GraphHelper) {
    // TODO
}

func listUsers(graphHelper *graphhelper.GraphHelper) {
    // TODO
}

func makeGraphCall(graphHelper *graphhelper.GraphHelper) {
    // TODO
}

This implements a basic menu and reads the user's choice from the command line.

Add app-only authentication

10 minutes remaining

In this section you will add app-only authentication to the application. his is required to obtain the necessary OAuth access token to call the Microsoft Graph. In this step you will integrate the Azure Identity Client Module for Go into the application and configure authentication for the Microsoft Graph SDK for Go.

The Azure Identity library provides a number of TokenCredential classes that implement OAuth2 token flows. The Microsoft Graph SDK uses those classes to authenticate calls to Microsoft Graph.

Configure Graph client for app-only authentication

In this section you will use the ClientSecretCredential class to request an access token by using the client credentials flow.

Add the following function to ./graphhelper/graphhelper.go.

func (g *GraphHelper) InitializeGraphForAppAuth() error {
    clientId := os.Getenv("CLIENT_ID")
    tenantId := os.Getenv("TENANT_ID")
    clientSecret := os.Getenv("CLIENT_SECRET")
    credential, err := azidentity.NewClientSecretCredential(tenantId, clientId, clientSecret, nil)
    if err != nil {
        return err
    }

    g.clientSecretCredential = credential

    // Create an auth provider using the credential
    authProvider, err := auth.NewAzureIdentityAuthenticationProviderWithScopes(g.clientSecretCredential, []string{
        "https://graph.microsoft.com/.default",
    })
    if err != nil {
        return err
    }

    // Create a request adapter using the auth provider
    adapter, err := msgraphsdk.NewGraphRequestAdapter(authProvider)
    if err != nil {
        return err
    }

    // Create a Graph client using request adapter
    client := msgraphsdk.NewGraphServiceClient(adapter)
    g.appClient = client

    return nil
}

Tip

If you are using goimports, some modules may have been auto-removed from your import statement in graphhelper.go on save. You may need to re-add the modules to build.

Replace the empty initializeGraph function in graphapponlytutorial.go with the following.

func initializeGraph(graphHelper *graphhelper.GraphHelper) {
    err := graphHelper.InitializeGraphForAppAuth()
    if err != nil {
        log.Panicf("Error initializing Graph for app auth: %v\n", err)
    }
}

This code initializes two properties, a DeviceCodeCredential object and a GraphServiceClient object. The InitializeGraphForUserAuth function creates a new instance of DeviceCodeCredential, then uses that instance to create a new instance of GraphServiceClient. Every time an API call is made to Microsoft Graph through the userClient, it will use the provided credential to get an access token.

Test the ClientSecretCredential

Next, add code to get an access token from the ClientSecretCredential.

Add the following function to ./graphhelper/graphhelper.go.

func (g *GraphHelper) GetAppToken() (*string, error) {
    token, err := g.clientSecretCredential.GetToken(context.Background(), policy.TokenRequestOptions{
        Scopes: []string{
            "https://graph.microsoft.com/.default",
        },
    })
    if err != nil {
        return nil, err
    }

    return &token.Token, nil
}

Replace the empty displayAccessToken function in graphapponlytutorial.go with the following.

func displayAccessToken(graphHelper *graphhelper.GraphHelper) {
    token, err := graphHelper.GetAppToken()
    if err != nil {
        log.Panicf("Error getting user token: %v\n", err)
    }

    fmt.Printf("App-only token: %s", *token)
    fmt.Println()
}

Build and run the app by running go run graphapponlytutorial. Enter 1 when prompted for an option. The application displays an access token.
```
Go Graph App-Only Tutorial

Please choose one of the following options:
0. Exit
1. Display access token
2. List users
3. Make a Graph call
1
App-only token: eyJ0eXAiOiJKV1QiLCJub25jZSI6IlVDTzRYOWtKYlNLVjVkRzJGenJqd2xvVUcwWS...
```
Tip

For validation and debugging purposes only, you can decode app-only access tokens using Microsoft's online token parser at https://jwt.ms. This can be useful if you encounter token errors when calling Microsoft Graph. For example, verifying that the role claim in the token contains the expected Microsoft Graph permission scopes.

List users

7 minutes remaining

In this section you will add the ability to list all users in your Azure Active Directory using app-only authentication.

Add the following function to ./graphhelper/graphhelper.go.

func (g *GraphHelper) GetUsers() (models.UserCollectionResponseable, error) {
    var topValue int32 = 25
    query := users.UsersRequestBuilderGetQueryParameters{
        // Only request specific properties
        Select: []string{"displayName", "id", "mail"},
        // Get at most 25 results
        Top: &topValue,
        // Sort by display name
        Orderby: []string{"displayName"},
    }

    return g.appClient.Users().
        Get(context.Background(),
            &users.UsersRequestBuilderGetRequestConfiguration{
                QueryParameters: &query,
            })
}

Replace the empty listUsers function in graphapponlytutorial.go with the following.

func listUsers(graphHelper *graphhelper.GraphHelper) {
    users, err := graphHelper.GetUsers()
    if err != nil {
        log.Panicf("Error getting users: %v", err)
    }

    // Output each user's details
    for _, user := range users.GetValue() {
        fmt.Printf("User: %s\n", *user.GetDisplayName())
        fmt.Printf("  ID: %s\n", *user.GetId())

        noEmail := "NO EMAIL"
        email := user.GetMail()
        if email == nil {
            email = &noEmail
        }
        fmt.Printf("  Email: %s\n", *email)
    }

    // If GetOdataNextLink does not return nil,
    // there are more users available on the server
    nextLink := users.GetOdataNextLink()

    fmt.Println()
    fmt.Printf("More users available? %t\n", nextLink != nil)
    fmt.Println()
}

Run the app, sign in, and choose option 2 to list users.

Please choose one of the following options:
0. Exit
1. Display access token
2. List users
3. Make a Graph call
2
User: Adele Vance
  ID: 05fb57bf-2653-4396-846d-2f210a91d9cf
  Email: [email protected]
User: Alex Wilber
  ID: a36fe267-a437-4d24-b39e-7344774d606c
  Email: [email protected]
User: Allan Deyoung
  ID: 54cebbaa-2c56-47ec-b878-c8ff309746b0
  Email: [email protected]
User: Bianca Pisani
  ID: 9a7dcbd0-72f0-48a9-a9fa-03cd46641d49
  Email: NO EMAIL
User: Brian Johnson (TAILSPIN)
  ID: a8989e40-be57-4c2e-bf0b-7cdc471e9cc4
  Email: [email protected]

...

More users available? true

Code explained

Consider the code in the GetUsers function.

It gets a collection of users
It uses Select to request specific properties
It uses Top to limit the number of users returned
It uses OrderBy to sort the response

Optional: add your own code

5 minutes remaining

In this section you will add your own Microsoft Graph capabilities to the application. This could be a code snippet from Microsoft Graph documentation or Graph Explorer, or code that you created. This section is optional.

Update the app

Add the following function to ./graphhelper/graphhelper.go.

func (g *GraphHelper) MakeGraphCall() error {
    // INSERT YOUR CODE HERE
    return nil
}

Replace the empty makeGraphCall function in graphapponlytutorial.go with the following.

func makeGraphCall(graphHelper *graphhelper.GraphHelper) {
    err := graphHelper.MakeGraphCall()
    if err != nil {
        log.Panicf("Error making Graph call: %v", err)
    }
}

Choose an API

Find an API in Microsoft Graph you'd like to try. For example, the Create event API. You can use one of the examples in the API documentation, or you can customize an API request in Graph Explorer and use the generated snippet.

Configure permissions

Check the Permissions section of the reference documentation for your chosen API to see which authentication methods are supported. Some APIs don't support app-only, or personal Microsoft accounts, for example.

To call an API with user authentication (if the API supports user (delegated) authentication), see the user (delegated) authentication tutorial.
To call an API with app-only authentication (if the API supports it), add the required permission scope in the Azure AD admin center.

Add your code

Copy your code into the MakeGraphCall function in graphhelper.go. If you're copying a snippet from documentation or Graph Explorer, be sure to rename the GraphServiceClient to appClient.

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Build Go apps with Microsoft Graph and app-only authentication

Prerequisites

Register the app in the portal

Register application for app-only authentication

Create a Go console app

Install dependencies

Load application settings

Design the app

Add app-only authentication

Configure Graph client for app-only authentication

Test the ClientSecretCredential

List users

Code explained

Optional: add your own code

Update the app

Choose an API

Configure permissions

Add your code

Congratulations!