Azure 函数 blob 绑定

如果不使用 C# 实现（不是 CSX）中的 [BlobAttribute]，我无法将 blob 类型的输入参数绑定到 string/TextReader。

我收到的错误是：

Microsoft.Azure.WebJobs.Host: Error indexing method 'Functions.Harvester'. 
Microsoft.Azure.WebJobs.Host: Cannot bind parameter 'configReader' to type 
TextReader. Make sure the parameter Type is supported by the binding. If 
you're using binding extensions (e.g. ServiceBus, Timers, etc.) make sure 
you've called the registration method for the extension(s) in your startup 
code (e.g. config.UseServiceBus(), config.UseTimers(), etc.).

功能.配置：

"bindings": [
    {
      "type": "timerTrigger",
      "schedule": "0 */5 * * * *",
      "useMonitor": true,
      "runOnStartup": false,
      "direction": "in",
      "name": "myTimer"
    },
    {
      "type": "blob",
      "name": "configReader",
      "path": "secured/app.config.json",
      "connection": "XXX",
      "direction": "in"
    }
  ],

函数签名（不绑定configReader):

[FunctionName("Harvester")]
 public static async Task Run(
   [TimerTrigger("0 */5 * * * *")]TimerInfo myTimer,
   TraceWriter log,
   TextReader configReader)

这虽然可行（绑定configReader:

[FunctionName("Harvester")]
 public static async Task Run(
   [TimerTrigger("0 */5 * * * *")]TimerInfo myTimer,
   TraceWriter log,
   [Blob("secured/app.config.json", FileAccess.Read)]TextReader configReader)

关于如何在不指定 blob 路径的情况下使其工作的任何想法BlobAttribute。理想情况下，我会将 Blob 配置保留在代码之外，这样我的函数将变得更加可移植。

事实证明，问题在于最新的运行时支持新属性（configurationSource) in function.json

这告诉运行时使用config（这是function.json) 或函数配置的 C# 属性。

本质上允许您像这样定义您的函数

现在您可以将函数定义为

[FunctionName("Harvester")]
public static async Task Run(
    [TimerTrigger]TimerInfo myTimer,
    TraceWriter log,
    TextReader configReader)
{
}

连同一个function.json看起来像这样

{
  "generatedBy": "Microsoft.NET.Sdk.Functions-1.0.0.0",
  "configurationSource": "config",
  "bindings": [
    {
      "type": "timerTrigger",
      "schedule": "0 */5 * * * *",
      "useMonitor": true,
      "runOnStartup": false,
      "direction": "in",
      "name": "myTimer"
    },
    {
      "type": "blob",
      "name": "configReader",
      "path": "secured/app.config.json",
      "connection": "XXX",
      "direction": "in"
    }
  ],
  "disabled": false,
  "scriptFile": "...",
  "entryPoint": "..."
}

或者像这样

[FunctionName("Harvester")]
public static async Task Run(
    [TimerTrigger("0 */5 * * * *")]TimerInfo myTimer,
    TraceWriter log,
    [Blob("secured/app.config.json", FileAccess.Read)]TextReader configReader)
{
}

像这样更简单的配置

{
  "generatedBy": "Microsoft.NET.Sdk.Functions-1.0.0.0",
  "configurationSource": "attributes",
  "bindings": [
    {
      "type": "timerTrigger",
      "name": "myTimer"
    },
  ],
  "scriptFile": "...",
  "entryPoint": "..."
}

记下 的值configurationSource在这两个例子中。

Visual Studio 2017 的工具默认执行后者。如果您想更改 function.json 以包含所有配置并更改configurationSource您需要将该文件包含在您的项目中并将其标记为始终复制。这个 GIF 展示了如何做到这一点。