Connecting To SharePoint Online Using Certificate Based Authentication In Azure Function

Step 4

Select the trigger type for this article. We have to use HTTP trigger but we can leverage any other triggers as well as per our choice.

Step 5 - Update the local.settings.json

Once the project is created open local.settings.json and update it with the below JSON.

Note
Please update the value of SiteUrl, TenantId, ClientId, CertificateThumbprint, and WEBSITE_LOAD_CERTIFICATES as per the values obtained from the above PowerShell execution.

{
    "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "SiteUrl": "https://testinglala.sharepoint.com/sites/Test",
    "TenantId": "52d05dd6-9e21-494f-8502-77658dbe16b8",
    "ClientId": "1ee21bec-967f-4801-8aa1-a0ebbf86280d",
    "CertificateThumbPrint": "F0..............................",
    "WEBSITE_LOAD_CERTIFICATES": "F0..............................."
  }
}

Step 6 - Add required Nuget Package

Add below Nuger Packages which would be required for extending the Azure Function and connecting SharePoint Online using PnP Core,

1. Microsoft.Azure.Functions.Extensions
2. PnP.Core.Auth

Step 7

Add AzureFunctionSettings.cs file into the Solution which will help us to get all the configuration for the Azure Function and update it with the below code,

using System;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace ConnectSharePointOnline
{
    class AzureFunctionSettings
    {
        public string SiteUrl { get; set; }
        public string TenantId { get; set; }
        public string ClientId { get; set; }
        public StoreName CertificateStoreName { get; set; }
        public StoreLocation CertificateStoreLocation { get; set; }
        public string CertificateThumbprint { get; set; }
    }
}

Step 8

Add a file named Startup.cs which will help us to add DependencyInjection to all the Azure Functions in the solution.

Update the Startup.cs file with the below code,

using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using PnP.Core.Auth;
using System;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates;
using System.Text;
[assembly: FunctionsStartup(typeof(ConnectSharePointOnline.Startup))]
namespace ConnectSharePointOnline {
    class Startup: FunctionsStartup {
        public override void Configure(IFunctionsHostBuilder builder) {
            var config = builder.GetContext().Configuration;
            var azureFunctionSettings = new AzureFunctionSettings();
            config.Bind(azureFunctionSettings);
            builder.Services.AddPnPCore(options => {
                // Disable telemetry because of mixed versions on AppInsights dependencies
                options.DisableTelemetry = true;
                // Configure an authentication provider with certificate (Required for app only)
                var authProvider = new X509CertificateAuthenticationProvider(azureFunctionSettings.ClientId, azureFunctionSettings.TenantId, StoreName.My, StoreLocation.CurrentUser, azureFunctionSettings.CertificateThumbprint);
                // And set it as default
                options.DefaultAuthenticationProvider = authProvider;
                // Add a default configuration with the site configured in app settings
                options.Sites.Add("Default", new PnP.Core.Services.Builder.Configuration.PnPCoreSiteOptions {
                    SiteUrl = azureFunctionSettings.SiteUrl,
                        AuthenticationProvider = authProvider
                });
            });
        }
    }
}

Step 9

Update the Function1.cs file where we can connect to SharePoint Online. For this example purpose we will bring all the documents present in the Shared Documents library.

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using PnP.Core.Services;
using PnP.Core.Model.SharePoint;
using System.Linq;
namespace ConnectSharePointOnline {
    public class Function1 {
        private readonly IPnPContextFactory pnpContextFactory;
        public Function1(IPnPContextFactory pnpContextFactory) {
                this.pnpContextFactory = pnpContextFactory;
            }
            [FunctionName("Function1")]
        public async Task < IActionResult > Run(
            [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req, ILogger log) {
            log.LogInformation("C# HTTP trigger function processed a request.");
            using(var pnpContext = await pnpContextFactory.CreateAsync("Default")) {
                log.LogInformation("Getting all the shared documents on site.");
                IList sharedDocuments = await pnpContext.Web.Lists.GetByTitleAsync("Documents", l => l.RootFolder);
                var sharedDocumentsFolder = await sharedDocuments.RootFolder.GetAsync(f => f.Files);
                var documents = (from d in sharedDocumentsFolder.Files.AsEnumerable() select new {
                    d.Name,
                        d.TimeLastModified,
                        d.UniqueId
                }).ToList();
                return new OkObjectResult(new {
                    documents
                });
            }
        }
    }
}

Outcome

Conclusion

In this article, we can understand how we can use Application permission to connect to SharePoint online using Certificate-based Authentication in the Azure Active Directory Application.