damoodamoo / azure-function-custom-binding

Sample to demonstrate the plumbing required for a custom binding extension for Azure Functions v2.

Azure Functions v2 Custom Binding Sample

This repo contains a few sample projects to demonstrate the architecture and plumbing needed when writing a custom binding in Azure Functions v2. It also contains sample implementation functions written in:

• C#
• JavaScript
• Java

Using this as a starting point should help you understand what's going on, and maybe provide a launch pad for your own project.

NOTE: The code provided here is sample code, please use as reference only and don't just copy straight into production. It has no warranty.

General Idea

The binding is (and has to be) written in C#. The project should make it clear where the hooks are for you to get data from a function (output binding), and supply data to a function (input binding).

Bindings are usually referenced in a .csproj file by Nuget package - but it turns out you can also reference local projects too, which is what happens here. For instance, in the JS function extensions.csproj, you'll see:

 <ItemGroup>
    <ProjectReference Include="..\DummyBinding\DummyBinding.csproj" />
  </ItemGroup>

If you're using a JS function with Core Tools...

Make sure to run:

func extensions sync

This will build the binding project and bring across the dlls - caught me out for a while.

Huge thanks to...

One reason I built this sample is to make it clearer how to put these things together, and big thanks to these guys for helping me understand it. Would recommend reading the following...

• Jason Roberts - http://dontcodetired.com/blog/post/Creating-Custom-Azure-Functions-Bindings
• Jan de Vries - https://jan-v.nl/post/create-your-own-custom-bindings-with-azure-functions