Imagine AWS Lambda being:

  • On-Premise (host it anywhere)
  • Language Agnostic (writing lambda functions in any language: Go, Rust, Python, Scala, Elixir you name it...)
  • Horizontally Scalable
  • Open-Source

Would be nice wouldn't it?


Well fear not released IronFunctions last week and its all that.

IronFunction supports a simple stdin/stdout API, as well as being able to import your existing functions directly from AWS Lambda.

Getting started!

You can grab the latest code from GitHub or just run it in docker:

docker run --rm -it --name functions --privileged -v $PWD/data:/app/data -p 8080:8080 iron/functions  

Currently IronFunctions supports importing the following languages from AWS Lambda:

The almighty fn tool

The fn tool includes a set of commands to act on Lambda functions. Most of these are described in the getting-started in the repository. One more subcommand is aws-import.
If you have an existing AWS Lambda function, you can use this command to automatically convert it to a Docker image that is ready to be deployed on other platforms.


To use this, either have your AWS access key and secret key set in config files, or in environment variables. In addition, you'll want to set a default region. You can use the aws tool to set this up. Full instructions are in the AWS documentation.


The aws-import command is constructed as follows:

fn lambda aws-import <arn> <region> <image>  
  • arn: describes the ARN formats which uniquely identify the AWS lambda resource
  • region: region on which the lambda is hosted
  • image: the name of the created docker image which should have the format /

Assuming you have a lambda with the following arn arn:aws:lambda:us-west-2:123141564251:function:my-function, the following command:

fn lambda aws-import arn:aws:lambda:us-west-2:123141564251:function:my-function us-east-1 user/my-function  

will import the function code from the region us-east-1 to a directory called ./user/my-function. Inside the directory you will find the function.yml, Dockerfile, and all the files needed for running the function.

Using Lambda with Docker Hub and IronFunctions requires that the Docker image be named <Docker Hub username>/<image name>. This is used to uniquely identify images on Docker Hub. You should use the <Docker Hub username>/<image name> as the image name with aws-import to create a correctly named image.

Publish and Voila!

You can then publish the imported lambda as follows:

./fn publish -d ./user/my-function

Now the function can be reached via http://$HOSTNAME/r/user/my-function

Make sure you check out the importing documentation, and feel free to hang out and ask question on the slack channel.
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Stay tuned for my next blog post on adding Cargo and Rust support to the Fn Tools :D