How can I use a BlobTrigger to bind to CloudBlockBlob in an Azure Function?

Question

I have the following function in my project:

[FunctionName("my-func")]
public static async Task Run([BlobTrigger("data/{name}")] CloudBlockBlob blob, string name, TraceWriter log)
{
    log.Info($"Started Processing: {name}");

    await blob.DeleteAsync();

    log.Info($"Finished Processing: {name}");
}

When I attempt to run the function locally using v1.0.4 of the Azure Functions CLI I get this error:

Microsoft.Azure.WebJobs.Host: Error indexing method 'SampleFunction.Run'. Microsoft.Azure.WebJobs.Host: Can't bind BlobTrigger to type 'Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlob'.

All documentation I have seen for Azure Functions and WebJobs SDK say this is supported.

https://github.com/Azure/azure-webjobs-sdk/wiki/Blobs#-types-that-you-can-bind-to-blobs

Mikhail Shilkov · Accepted Answer · 2017-10-25 19:54:15Z

7

You are probably referencing some NuGet package that has a dependency on non-compatible version of WindowsAzure.Storage assembly (version 8.x.x). If so, be sure to remove it. Unless you are using some additional binding, your csproj references should look as simple as this:

<ItemGroup>           
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="1.0.6" />
</ItemGroup>

answered Oct 25, 2017 at 19:54

Mikhail Shilkov

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2 Comments

Mike Over a year ago

That was exactly the issue. I had other code that required 8.x.x that I removed to simplify the example. Once I removed the reference everything worked as expected. Thanks!

Mikhail Shilkov Over a year ago

Yeh, that's a known problem with assembly version conflicts and lack of binding redirects. Very confusing, but no proper solution yet.

Kevin Smith · Accepted Answer · 2017-10-25 19:59:08Z

0

Make sure you are running the Azure Storage Emulator:

cd C:\Program Files (x86)\Microsoft SDKs\Azure\Storage Emulator

C:\Program Files (x86)\Microsoft SDKs\Azure\Storage Emulator> AzureStorageEmulator.exe start
Windows Azure Storage Emulator 5.2.0.0 command line tool
Autodetect requested. Autodetecting SQL Instance to use.
Looking for a LocalDB Installation.
Probing SQL Instance: '(localdb)\MSSQLLocalDB'.
Found a LocalDB Installation.
Probing SQL Instance: '(localdb)\MSSQLLocalDB'.
Found SQL Instance (localdb)\MSSQLLocalDB.
Creating database AzureStorageEmulatorDb52 on SQL instance '(localdb)\MSSQLLocalDB'.

answered Oct 25, 2017 at 19:59

Kevin Smith

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1 Comment

Mikhail Shilkov Over a year ago

He's probably just connecting to Azure Storage. Connectivity issue will give another error.

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