Can someone describe me how I can configure a C# azure function which uses an HTTP input trigger and a blob storage output trigger?
Maybe also with an example code snippet and an example function.json. I don't get it to work locally with the azure functions core tools.
This is a combined HTTP triggered function with a output blob binding:
[FunctionName("HttpTriggeredFunction")]
public static async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest httpRequest,
[Blob("blobcontainer", Connection = "StorageConnectionString")] CloudBlobContainer outputContainer,
ILogger log)
{
log.LogInformation("C# HTTP trigger function processed a request.");
await outputContainer.CreateIfNotExistsAsync();
var requestBody = await new StreamReader(httpRequest.Body).ReadToEndAsync();
var blobName = Guid.NewGuid().ToString();
var cloudBlockBlob = outputContainer.GetBlockBlobReference(blobName);
await cloudBlockBlob.UploadTextAsync(requestBody);
return new OkObjectResult(blobName);
}
It uses the CloudBlobContainer output type to get a reference to the blob container which then enables you to use methods such as .GetBlockBlobReference("blobPath") to get a reference to a blob.
Once you have a reference to a blob, you can use different methods to upload:
cloudBlockBlob.UploadFromByteArrayAsync()cloudBlockBlob.UploadFromFileAsync()cloudBlockBlob.UploadTextAsync()cloudBlockBlob.UploadFromStreamAsync()To get it running locally, you need set some things up. Notice in my example the attribute [Blob("blobcontainer", Connection = "StorageConnectionString")]
outputContainer.CreateIfNotExistsAsync(); (if it doesn't exist already).local.settings.json for the connection string of your storage account. When developing locally I would recommend setting this to "UseDevelopmentStorage=true" so that you can take advantage of the storage emulator. Then when you are ready to deploy onto Azure, you would create a setting in the function app containing the real connection string.local.settings.json
{
"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"FUNCTIONS_WORKER_RUNTIME": "dotnet",
"StorageConnectionString": "UseDevelopmentStorage=true"
}
}
to make an http function that saves to Blob Storage use this code:
#r "Newtonsoft.Json"
using System.Net;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Primitives;
using Newtonsoft.Json;
public static async Task<IActionResult> Run(HttpRequest req, ILogger log,TextWriter outputBlob)
{
string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
outputBlob.WriteLine(requestBody);
string result = "{ 'result': 'ok' }";
dynamic data = JsonConvert.DeserializeObject(result);
return new OkObjectResult(data);
}
You need to set the output binding:
You can then run a test posting content on the test window
This is the simplest code to accomplish this task.
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
public static IActionResult Run(HttpRequest req, out string outputBlob)
{
outputBlob = "This is a Blob content";
return new OkResult();
}
The input and output parameters are specified in the function.json file and are additionally presented graphically in the Integration tab.
function.json file content:
{"bindings":[{"authLevel": "ANONYMOUS",
"name": "req",
"type": "httpTrigger",
"direction": "in",
"methods": ["get","post"]
},{
"name": "$return",
"type": "http",
"direction": "out"
},{
"name": "outputBlob",
"direction": "out",
"type": "blob",
"path": "outcontainer/{rand-guid}",
"connection": "AzureWebJobsStorage"
}]}
Integration tab content:
local.settings.json file content
{"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"FUNCTIONS_WORKER_RUNTIME": "dotnet" }}
The function can be extended by adding logging and reading data from the request.
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
using System;
public static IActionResult Run(HttpRequest req, out string outputBlob, ILogger log)
{
log.LogInformation("C# HTTP trigger function processed a request.");
outputBlob = $"This Blob was created by HttpTrigger1 because at {DateTime.Now} request was sent to: {req.Host}";
return new OkResult();
}
Everything you need is there in the Official docs page,
(ii)Output binding blob storage
Http Trigger Sample code
[FunctionName("HttpTriggerCSharp")]
public static async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)]
HttpRequest req, ILogger log)
Blob Storage Output binding
[FunctionName("ResizeImage")]
public static void Run(
[BlobTrigger("sample-images/{name}")] Stream image,
[Blob("sample-images-sm/{name}", FileAccess.Write)] Stream imageSmall,
[Blob("sample-images-md/{name}", FileAccess.Write)] Stream imageMedium)
