karlheinzkurt/cash-machine

Playground with Rust and OpenFaaS running on a local ARM driven k8s cluster

Motivation

Just a playground project to explore the Rust programming language and OpenFaaS. Since I'm quite used to C++, I wanted to find out the advantages of Rust. Furthermore, I'm concerned about size of docker images in real world projects and I would like to find ways to implement features in languages providing a sufficient ecosystem but keeping the image size of the increasing number of docker images as small as possible.

What it does?

Takes an amount of money as an argument and calculates the notes to be paid out to the customer (without any practical use, just to play).

Requirements

• https://medium.com/@alexellisuk/walk-through-install-kubernetes-to-your-raspberry-pi-in-15-minutes-84a8492dc95a
• https://www.docker.com/blog/multi-arch-images/

Deploy to local k8s cluster hosting OpenFaaS and running on RasberryPis

Since multi-platform builds are not yet supported right now (openfaas/faas-cli#770), we have to build and deploy the function in multiple steps. Build image locally to ensure faas-cli copies the template stuff to the right places.

faas-cli build --shrinkwrap -f cash-machine.yml

Build images for amd64, arm64, arm/v7 and push them.

pushd build/cash-machine
docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 -t karlheinzkurt/cash-machine:latest --push .
popd

Deploy function to local cluster, while 192.168.23.10 is the IPv4 of my local cluster and should be changed properly.

export OPENFAAS_URL=http://192.168.23.10:31112
faas-cli deploy -f cash-machine.yml

Use the function.

curl -s http://192.168.23.10:31112/function/cash-machine -d '{"amount":188}' | json_pp
{
   "notes" : {
      "1" : 1,
      "50" : 1,
      "5" : 1,
      "20" : 1,
      "2" : 1,
      "10" : 1,
      "100" : 1
   }
}

TODOs

• Make error handling RFC7807 conform: https://tools.ietf.org/html/rfc7807
• To avoid forking the process for each request: https://github.com/openfaas-incubator/of-watchdog/blob/master/README.md

OpenFaaS helper

• https://docs.openfaas.com/deployment/troubleshooting/

k3s helper

Clean-up docker images

sudo k3s crictl images
sudo k3s crictl rmi --prune