RetrieveSiteAdmins.csx

/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* Jarbas Horst wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return.
* ----------------------------------------------------------------------------
*/

using System.Net;
using System.Collections.Generic;
using OfficeDevPnP.Core;
using OfficeDevPnP.Core.Entities;
using Microsoft.SharePoint.Client;

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
    try
    {
        // Gets data from request body.
        dynamic data = await req.Content.ReadAsAsync<object>();
        string siteUrl = data.SiteUrl;
        if(String.IsNullOrEmpty(siteUrl))
            return req.CreateResponse(HttpStatusCode.BadRequest, "Please pass site URL in request body!");

        // Fetches client id and client secret from app settings.
        string clientId = System.Environment.GetEnvironmentVariable("ClientId", EnvironmentVariableTarget.Process);
        string clientSecret = System.Environment.GetEnvironmentVariable("ClientSecret", EnvironmentVariableTarget.Process);

        // Obtains client context using the client id and client secret.
        ClientContext ctx = new OfficeDevPnP.Core.AuthenticationManager().GetAppOnlyAuthenticatedContext(siteUrl, clientId, clientSecret);
        
        // Retrieves site collection administrators.
        List<UserEntity> admins = ctx.Web.GetAdministrators();

        string response = String.Format("{0}", String.Join(", ", admins.Select(x => x.Title)));
        return req.CreateResponse(HttpStatusCode.OK, response);
    }
    catch (Exception e)
    {
        return req.CreateResponse(HttpStatusCode.InternalServerError, e.Message);
    }
}