RetrieveAzureVmData_wFuncAppMI.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Azure.Identity;
using Azure.Storage.Blobs;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;

using Microsoft.Azure.Management.ResourceGraph;
using Microsoft.Rest;
using Microsoft.Azure.Management.ResourceGraph.Models;
using Microsoft.Azure.Management.Subscription;
using Microsoft.Azure.Management.Subscription.Models;
using Newtonsoft.Json.Linq;

namespace RetrieveAzureVmData_wFuncAppMI
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static async Task Run([TimerTrigger("0 */15 * * * *")] TimerInfo myTimer, ILogger log)
        {
            log.LogInformation($"Starting function at: {DateTime.Now}");
            
            string accessToken = await ExtractAccessTokenFromCredentials(
                new ManagedIdentityCredential());
            await WriteVmDataToStorageAccount(await GetVMData(accessToken, await GetAllAzureSubscriptions(accessToken, log), log));

            log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
        }

        private static async Task<string> ExtractAccessTokenFromCredentials(Azure.Core.TokenCredential tokenCredential)
        {
            // Extract the access token from the supplied credentials
            var accessToken = await tokenCredential.GetTokenAsync(
                new Azure.Core.TokenRequestContext(new string[] { "https://management.core.windows.net/.default" }),
                new System.Threading.CancellationToken());
            return accessToken.Token;
        }

        private static async Task<List<string>> GetAllAzureSubscriptions(string accessToken, ILogger log)
        {
            // Pack the credentials in the format required next
            ServiceClientCredentials serviceClientCreds = new TokenCredentials(accessToken);

            // Get the subscriptions
            SubscriptionClient subscriptionClient = new SubscriptionClient(serviceClientCreds);
            IEnumerable<SubscriptionModel> allSubscriptions = await subscriptionClient.Subscriptions.ListAsync();

            log.LogInformation($"{allSubscriptions.Count()} subscriptions retrieved");

            // Extract the subscriptions' ids
            List<string> allSubscriptionIds = new List<string>();
            foreach (var subscription in allSubscriptions)
            {
                allSubscriptionIds.Add(subscription.SubscriptionId);
            }
            return allSubscriptionIds;
        }
        
        private static async Task<Newtonsoft.Json.Linq.JArray> GetVMData(string accessToken,
            List<string> listOfAllAzureSubscriptionIds, ILogger log)
        {
            ServiceClientCredentials serviceClientCreds = new TokenCredentials(accessToken);
            ResourceGraphClient argClient = new ResourceGraphClient(serviceClientCreds);

            string strQuery = @"Resources
	            | where type =~ 'microsoft.compute/virtualmachines'
	            | project id, vmId = tolower(tostring(id)), vmName = name
	            | join (Resources
	                | where type =~ 'microsoft.network/networkinterfaces'
	                | mv-expand ipconfig=properties.ipConfigurations
	                | project vmId = tolower(tostring(properties.virtualMachine.id)), privateIp = ipconfig.properties.privateIPAddress, publicIpId = tostring(ipconfig.properties.publicIPAddress.id)
	                | join kind=leftouter (Resources
	                    | where type =~ 'microsoft.network/publicipaddresses'
	                    | project publicIpId = id, publicIp = properties.ipAddress
	                ) on publicIpId
	                | project-away publicIpId, publicIpId1
	                | summarize privateIps = make_list(privateIp), publicIps = make_list(publicIp) by vmId
	            ) on vmId
	            | project-away vmId, vmId1
	            | sort by vmName asc";

            QueryRequest request = new QueryRequest();
            request.Subscriptions = listOfAllAzureSubscriptionIds;
            request.Query = strQuery;
            request.Options = new QueryRequestOptions { ResultFormat = ResultFormat.ObjectArray };

            JArray allVmData = new JArray();
            QueryResponse response;
            do
            {
                response = null;
                try
                {
                    response = await argClient.ResourcesAsync(request);
                    request.Options.SkipToken = response.SkipToken;
                }
                catch (Exception e)
                {
                    log.LogInformation(e.ToString());
                }

                log.LogInformation("No of records in current response page: " + response.Count);

                allVmData.Merge(response.Data);
            } while (!string.IsNullOrEmpty(response.SkipToken));

            return allVmData;
        }

        private static async Task WriteVmDataToStorageAccount(Newtonsoft.Json.Linq.JArray allVmData)
        {
            string blockBlobName = "azureVMs.json";
            // Hard-coded connection string below. It would be ideal to read this from Azure Vault
            var connectionString = "STORAGE_ACCOUNT_CONNECTION_STRING";

            // Build the object that will connect to the container within our target storage account
            BlobContainerClient blobContainerClient = new BlobContainerClient(connectionString, "STORAGE_ACCOUNT_CONTAINER_NAME");
            // Write to Azure Blob Storage
            BlobClient blobClient = blobContainerClient.GetBlobClient(blockBlobName);
            using (MemoryStream memoryStream = new MemoryStream(Encoding.UTF8.GetBytes(allVmData.ToString())))
            {
                await blobClient.UploadAsync(memoryStream, true);
            }
        }
    }
}