一切為了安全，所有的雲上資源如支援內網資源訪問，則都可以加入虛擬網路
問題描述
使用Azure Function處理Storage Account中Blob 新增，更新，刪除等情況。Storage Account啟用虛擬網路中的服務終結點(Service Endpoint)後，可以實現只能從內網訪問。同時，Azure Function也支援整合內網。並且可支援在虛擬網路中被Storage Account所觸發。所以根據門戶中一步一步的操作，配置完Azure Function和Storage Account的Virtul Network後，發現Function無法啟動。在日誌中發現問題是：
2021-06-30T10:56:00.895 [Error] An unhandled exception has occurred. Host is shutting down. Microsoft.Azure.Storage.StorageException : This request is not authorized to perform this operation. at async Microsoft.Azure.Storage.Core.Executor.Executor.ExecuteAsync[T](RESTCommand`1 cmd,IRetryPolicy policy,OperationContext operationContext,CancellationToken token) at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at async Microsoft.Azure.WebJobs.Extensions.Storage.TimeoutHandler.ExecuteWithTimeout[T](String operationName,String clientRequestId,IWebJobsExceptionHandler exceptionHandler,ILogger logger,CancellationToken cancellationToken,Func`1 operation) at C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Extensions.Storage\TimeoutHandler.cs : 56 at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at async Microsoft.Azure.WebJobs.Host.Queues.Listeners.QueueListener.ExecuteAsync(CancellationToken cancellationToken) at C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Extensions.Storage\Queues\Listeners\QueueListener.cs : 201 at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at async Microsoft.Azure.WebJobs.Host.Timers.TaskSeriesTimer.RunAsync(CancellationToken cancellationToken) at C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Timers\TaskSeriesTimer.cs : 147 2021-06-30T10:56:00.921 [Information] Stopping JobHost 2021-06-30T10:56:00.921 [Information] Stopping the listener 'Microsoft.Azure.WebJobs.Host.Listeners.CompositeListener' for function 'BlobTrigger1' 2021-06-30T10:56:00.942 [Information] Stopped the listener 'Microsoft.Azure.WebJobs.Host.Listeners.CompositeListener' for function 'BlobTrigger1' 2021-06-30T10:56:00.943 [Information] Job host stopped
（日誌可通過高階工具Kudu獲取：Kudu地址為：https://<your function app name>.scm.chinacloudsites.cn/DebugConsole 日誌路徑為：D:\home\LogFiles\Application\Functions\Host\xxxxxxxx.log)
問題分析
根據日誌發現了：
1） Function Host遇見了異常，導致它被關閉.
2）異常的原因是因為訪問Storage沒有許可權 （Microsoft.Azure.Storage.StorageException : This request is not authorized to perform this operation.）
那麼問題根源就出現在Azure Function訪問Stroage時，走的是公網訪問，而公網的訪問在Storage中式拒絕的。所以要修改Funciton的配置，讓其通過內網的形式訪問Storage。在檢視官方說明文件後，有發現兩個非常重要的配置：
- WEBSITE_VNET_ROUTE_ALL：設定為1。它會將Azure Function的所有出站呼叫傳送到 VNet。
- WEBSITE_DNS_SERVER：預設值為168.63.129.16。用與虛擬網路整合時，它將使用與虛擬網路相同的 DNS 伺服器。 函式應用需要此設定才能與 Azure DNS 專用區域配合使用。 此設定和 WEBSITE_VNET_ROUTE_ALL 會將應用中的所有出站呼叫傳送到虛擬網路。
問題解決
在Azure Funciton的設定頁面，新增WEBSITE_VNET_ROUTE_ALL和WEBSITE_DNS_SERVER兩個引數，配置如下：
修改完成後，再次檢視Function Host的啟動日誌，就可見 “Loading functions metadata” 和 “1 functions loaded”等訊息。這就表明，Function Host啟動成功。
2021-06-30T10:57:00.006 [Information] Initializing Warmup Extension. 2021-06-30T10:57:00.069 [Information] Initializing Host. OperationId: '93cf4ed0-d598-4308-9241-dca5ba6a55ee'. 2021-06-30T10:57:00.073 [Information] Host initialization: ConsecutiveErrors=0, StartupCount=1, OperationId=93cf4ed0-d598-4308-9241-dca5ba6a55ee 2021-06-30T10:57:00.106 [Information] LoggerFilterOptions { "MinLevel": "None", "Rules": [ { "ProviderName": null, "CategoryName": null, "LogLevel": null, "Filter": "<AddFilter>b__0" }, { "ProviderName": "Microsoft.Azure.WebJobs.Script.WebHost.Diagnostics.SystemLoggerProvider", "CategoryName": null, "LogLevel": "None", "Filter": null }, { "ProviderName": "Microsoft.Azure.WebJobs.Script.WebHost.Diagnostics.SystemLoggerProvider", "CategoryName": null, "LogLevel": null, "Filter": "<AddFilter>b__0" } ] } 2021-06-30T10:57:00.107 [Information] FunctionResultAggregatorOptions { "BatchSize": 1000, "FlushTimeout": "00:00:30", "IsEnabled": true } 2021-06-30T10:57:00.107 [Information] SingletonOptions { "LockPeriod": "00:00:15", "ListenerLockPeriod": "00:00:15", "LockAcquisitionTimeout": "10675199.02:48:05.4775807", "LockAcquisitionPollingInterval": "00:00:05", "ListenerLockRecoveryPollingInterval": "00:01:00" } 2021-06-30T10:57:00.107 [Information] QueuesOptions { "BatchSize": 16, "NewBatchThreshold": 8, "MaxPollingInterval": "00:00:02", "MaxDequeueCount": 5, "VisibilityTimeout": "00:00:00" } 2021-06-30T10:57:00.107 [Information] BlobsOptions { "CentralizedPoisonQueue": false } 2021-06-30T10:57:00.108 [Information] Starting JobHost 2021-06-30T10:57:00.110 [Information] Starting Host (HostId=lbfunctionforvnet01, InstanceId=05efd41a-013d-428c-b839-fb4b69127366, Version=3.0.15733.0, ProcessId=5480, AppDomainId=1, InDebugMode=True, InDiagnosticMode=False, FunctionsExtensionVersion=~3) 2021-06-30T10:57:00.121 [Information] Loading functions metadata 2021-06-30T10:57:00.137 [Information] 1 functions loaded 2021-06-30T10:57:01.348 [Information] Generating 1 job function(s) 2021-06-30T10:57:01.373 [Information] Found the following functions: Host.Functions.BlobTrigger1
最後在Storage Blob中上傳檔案進行測試，Function能成功被觸發及獲取到正確的Blob資訊
2021-06-30T11:02:22.273 [Information] Executing 'Functions.BlobTrigger1' (Reason='New blob detected: samples-workitems/local_error.log', Id=79bc13b9-5aed-487f-b5de-02bb4ff7b8c6) 2021-06-30T11:02:22.276 [Information] Trigger Details: MessageId: f6dd9893-f6c6-41af-a469-f6b2e21e09bc, DequeueCount: 1, InsertionTime: 2021-06-30T11:02:22.000+00:00, BlobCreated: 2021-06-30T11:02:13.000+00:00, BlobLastModified: 2021-06-30T11:02:13.000+00:00 2021-06-30T11:02:22.283 [Information] C# Blob trigger function Processed blob Name:local_error.log Size: 420588 Bytes 2021-06-30T11:02:22.291 [Information] Executed 'Functions.BlobTrigger1' (Succeeded, Id=79bc13b9-5aed-487f-b5de-02bb4ff7b8c6, Duration=37ms)
參考資料
具有虛擬網路觸發器的高階計劃 ：https://docs.azure.cn/zh-cn/azure-functions/functions-networking-options#premium-plan-with-virtual-network-triggers