.NET Core#

This document describes the specific .NET Core build and deploy configurations.

In this document#

Function and handler#

using System;
using Nuclio.Sdk;

public class nuclio
    public object empty(Context context, Event eventBase)
        return new Response()
            StatusCode = 200,
            ContentType = "application/text",
            Body = ""

The handler field is of the form <class>:<entrypoint>. In the example above, the handler is nuclio:empty.

Project file#

To use or import external dependencies, create a handler.csproj file that lists the required dependencies, alongside your function-handler file.

For example, the following file defines a dependency on the Microsoft.NET.Sdk package:

<Project Sdk="Microsoft.NET.Sdk">
        <PackageReference Include="Newtonsoft.Json" Version="12.0.2"/>

With this example handler.csproj file, you can use the Newtonsoft.Json package as follows:

using Newtonsoft.Json;

Adding more dependencies is made easy using dotnet add package <package name>. For more details about dotnet add package, see the Microsoft documentation.


See Deploying Functions from a Dockerfile.

ARG NUCLIO_BASE_IMAGE=mcr.microsoft.com/dotnet/sdk:7.0
ARG NUCLIO_ONBUILD_IMAGE=nuclio/handler-builder-dotnetcore-onbuild:${NUCLIO_LABEL}-${NUCLIO_ARCH}

# Supplies processor uhttpc, used for healthcheck
FROM nuclio/uhttpc:0.0.1-amd64 as uhttpc

# Builds source, supplies processor binary and handler plugin

# From the base image

# Copy required objects from the suppliers
COPY --from=builder /home/nuclio/bin/processor /usr/local/bin/processor
COPY --from=builder /home/nuclio/bin/wrapper /opt/nuclio/wrapper
COPY --from=builder /home/nuclio/bin/handler /opt/nuclio/handler
COPY --from=builder /home/nuclio/src/nuclio-sdk-dotnetcore /opt/nuclio/nuclio-sdk-dotnetcore
COPY --from=uhttpc /home/nuclio/bin/uhttpc /usr/local/bin/uhttpc

# Readiness probe
HEALTHCHECK --interval=1s --timeout=3s CMD /usr/local/bin/uhttpc --url || exit 1

# Run processor with configuration and platform configuration
CMD [ "processor" ]

Writing a .NET Core 7.0 Function#

This guide uses practical examples to guide you through the process of writing serverless .NET Core functions.

In this document#


The .NET Core runtime allows function developers to create serverless functions using .NET Core 3.1. This guide walks you through the function-creation process.

Deploy a .NET Core function#

This example guides you through the steps for deploying a .NET Core code that reverses the event’s body. To implement this, you call reverser and pass an input;

Create a /tmp/nuclio-dotnetcore-script/reverser.cs file with the following code:

// @nuclio.configure
// function.yaml:
//   spec:
//     runtime: dotnetcore
//     handler: nuclio:reverser

using System;
using Nuclio.Sdk;

public class nuclio
    public string reverser(Context context, Event eventBase)
        var charArray = eventBase.GetBody().ToCharArray();
        return new string(charArray);

The function configuration needs to include the following:

  1. runtime - set to dotnetcore.

  2. handler - set to the name of the class and the name of the method . In this example, the handler is nuclio:reverser.

Run the following command to deploy the function with the Nuclio CLI (nuctl).

Note: If you’re not running on top of Kubernetes, pass the --platform local option to nuctl.

nuctl deploy -p /tmp/nuclio-dotnetcore-script/reverser.cs reverser

You can also remove the settings from reverser.cs and run the following command:

nuctl deploy -p /tmp/nuclio-dotnetcore-script/reverser.cs --runtime dotnetcore --handler nuclio:reverser reverser

And now, use the nuctl CLI to invoke the function:

$ nuctl invoke reverser -m POST -b reverse-me

> Response headers:
Date = Sun, 03 Dec 2017 12:53:51 GMT
Content-Type = text/plain; charset=utf-8
Content-Length = 10
Server = nuclio

> Response body:

See also#