openfaas

OpenFaaS

Introduction

OpenFaaS provides event-driven compute using functions and also supports traditional microservices.

All services are either functions or microservices, which are built into Docker images. Once pushed to a Docker image, the CLI or REST can be used to deploy the endpoint. It will become available on the OpenFaaS gateway.

The Gateway can be accessed through its REST API, via the CLI or through the UI. All services or functions get a default route exposed, but custom domains can also be used for each endpoint. Prometheus collects metrics which are available via the Gateway's API and which are used for auto-scaling.

By changing the URL for a function from /function/NAME to /async-function/NAME an invocation can be run in a queue using NATS Streaming. You can also pass an optional callback URL via the header X-Callback-Url.

Deployment

Get the OpenFaaS CLI

Run this command on your laptop

curl -sLS https://cli.openfaas.com | sh
chmod +x faas-cli
sudo mv faas-cli /usr/bin/

Deploy OpenFaaS with helm3

Run this command on your laptop

The k3sup binary installs OpenFaaS using helm3 and its chart:

• Get k3sup - for Mac, Windows or Linux

curl -sLS https://get.k3sup.dev | sh
sudo install k3sup /usr/bin/

• Deploy OpenFaaS

k3sup app install openfaas \
  --gateways 2 \
  --queue-workers 4

Follow the output at the end of the installation to test the deployment, do this from your laptop and not on the remote cluster.

kubectl rollout status -n openfaas deploy/gateway
kubectl port-forward -n openfaas svc/gateway 8080:8080 &

# If basic auth is enabled, you can now log into your gateway:
PASSWORD=$(kubectl get secret -n openfaas basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode; echo)
echo -n $PASSWORD | faas-cli login --username admin --password-stdin

Now deploy a function from the store and invoke it:

faas-cli store list
faas-cli store deploy nodeinfo

# Check for the Pod to become available ("Status: Ready")

faas-cli describe nodeinfo

echo verbose | faas-cli invoke nodeinfo

Create your own function (optional)

Run this command on your laptop

All functions need to be pushed to a registry, whether in-cluster, using a managed product or the Docker Hub.

If you want to follow this part of the lab, you'll need to install Docker on your laptop

The Docker Hub is the easiest option, for example:

export OPENFAAS_PREFIX="alexellis2"
docker login --username $OPENFAAS_PREFIX

# List available templates
faas-cli template store list

# Create a Node.js 12 async/await function:
faas-cli new --lang node12 db-inserter

# We can use one file for all the functions
mv db-inserter.yml stack.yml

This gives us:

├── db-inserter
│   ├── handler.js
│   └── package.json
└── stack.yml

Example of handler.js:

"use strict"

module.exports = async (event, context) => {
    let err;
    const result =             {
        status: "Received input: " + JSON.stringify(event.body)
    };

    return context
        .status(200)
        .succeed(result);
}

Deploy:

# Build / push / deploy
faas-cli build
faas-cli push
faas-cli deploy

# Or all-in-one

faas-cli up

View the function on the OpenFaaS UI or invoke via faas-cli invoke db-insert.

Technical support

Seek out technical support on the OpenFaaS Slack

Take it further

Hands-on training:

• OpenFaaS blog
• Official Workshop
• Apply TLS with cert-manager

Reference:

• Event triggers

• MQTT Connector

• Async / queueing

• Secret management