First serverless Python function with OpenFaaS

This wiki describes how to create your first serverless python function with OpenFaaS. OpenFaas is a serverless framework for Docker and Kubernetes.

https://www.openfaas.com/

The instructions are directly copied from the blog by Alex Ellis below, with minor comments added.

https://blog.alexellis.io/first-faas-python-function/

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Install OpenFaaS

On Raspberry Pi, install Docker

curl -sSL https://get.docker.com | sh
sudo usermod -aG docker pi

and reboot. The Docker installation on Mac can be done through Homebrew:

brew install ruby
brew cask install docker

Initialize Swarm mode on your Docker daemon.

docker swarm init

You now have a single-node Docker cluster. That is all we need to deploy the FaaS stack and sample functions.

git clone https://github.com/openfaas/faas
cd faas
./deploy_stack.sh

The default stack contains sample functions, you can play with them via the UI at http://localhost:8080.

Install CLI on Raspberry Pi

curl -sSL https://cli.openfaas.com | sudo sh

or on Mac

brew install faas-cli

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Write your first function

Create a new Python function using the CLI.

mkdir -p ~/functions && cd ~/functions
faas-cli new --lang python hello-python

This creates three files for you:

hello-python/handler.py  
hello-python/requirements.txt  
hello-python.yml

Edit the handler.py file in the following way:

def handle(req):  
    print("Hello! You said: " + req)

Build the function:

faas-cli build -f ./hello-python.yml

See the image:

docker images | grep hello-python

Deploy the function:

faas-cli deploy -f ./hello-python.yml

List the available functions:

faas-cli list

Invoke function in one of the following ways:

curl localhost:8080/function/hello-python -d "it's David here"
echo "it's David here" | faas-cli invoke hello-python

You can also invoke the function from a different machine on your local network:

curl 192.168.2.2:8080/function/hello-python -d "it's David here"