Provides the ability to generate an Access Token from Azure Active Directory

Token.cs

using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text.Json;

var accessToken = await GetAccessTokenAsync();

async Task<string> GetAccessTokenAsync()
{
    /*
     * Environment variables
     */
    var tenantId = Environment.GetEnvironmentVariable("AZURE_TENANT_ID");
    if (tenantId is null)
    {
        Console.WriteLine("Environment variable AZURE_TENANT_ID is not set");
        Environment.Exit(1);
    }

    var clientId = Environment.GetEnvironmentVariable("AZURE_CLIENT_ID");
    if (clientId is null)
    {
        Console.WriteLine("Environment variable AZURE_CLIENT_ID is not set");
        Environment.Exit(1);
    }

    var clientSecret = Environment.GetEnvironmentVariable("AZURE_CLIENT_SECRET");
    if (clientSecret is null)
    {
        Console.WriteLine("Environment variable AZURE_CLIENT_SECRET is not set");
        Environment.Exit(1);
    }

    var client = new HttpClient();
    client.BaseAddress = new Uri("https://login.microsoftonline.com/");
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var body = new List<KeyValuePair<string, string>>
    {
        new KeyValuePair<string, string>("grant_type", "client_credentials"),
        new KeyValuePair<string, string>("client_id", clientId),
        new KeyValuePair<string, string>("client_secret", clientSecret),
        new KeyValuePair<string, string>("resource", "https://management.azure.com/")
    };

    HttpResponseMessage response = new HttpResponseMessage();

    try
    {
        response = await client.PostAsync($"{tenantId}/oauth2/token", new FormUrlEncodedContent(body));
        response.EnsureSuccessStatusCode();
    }
    catch (HttpRequestException re)
    {
        Console.WriteLine(re.Message);
        Environment.Exit(1);
    }

    var data = JsonSerializer.Deserialize<Token>(await response.Content.ReadAsStringAsync());
    if (data is null)
    {
        Console.WriteLine("Failed to deserialize the response");
        Environment.Exit(1);
    }

    return data.AccessToken;
}