OpenFaaS Charm example

Introduction

This repo is part of a Proof of Concept using the Canonical Operator framework

The charm is not for production use, is not maintained and is not fully functional.

We are not accepting contributions.

Components

OpenFaaS consists of the following components:

• gateway - the REST API and UI, requires NATS and Prometheus
• gateway.provider - a sidecar which provides a Kubernetes operator for creating functions and secrets for functions
• basic-auth-plugin - can be swapped for SSO/OIDC, but by default provides auth for the REST API
• prometheus - used for auto-scaling decisions and metrics in the REST API / UI
• NATS - for async invocations
• queue-worker - to subscribe to NATS and to invoke functions via the gateway

Charms

Each charm has its own readme and more detailed information.

• See openfaas operator: openfaas
• See NATS operator: nats-operator
• See openfaas-queue-worker: openfaas-queue-worker

Limitations and WIP

• The queue-worker cannot be deployed due to issues with the Operator framework expecting TCP ports.
• The Prometheus charm cannot be deployed, so auto-scaling is not working and neither are metrics. There will be errors in the logs for the gateway, but invocations work.

Trying OpenFaaS with the example

Providing that charmcraft, juju, and microk8s are set up, you can run the following.

• Change N=1 to N=2 for each change made, which needs to be redeployed.
• add-model corresponds to a Kubernetes namespace

(
    export N=1
    juju add-model d$N
    cd nats-operator
    charmcraft build && juju deploy ./nats.charm
    cd ..

    cd openfaas
    charmcraft build && juju deploy ./openfaas.charm 
    cd ..

    juju relate openfaas nats
)

Check the status of the components:

watch "juju status"

Follow the juju debug log:

juju debug-log

Download faas-cli

Login to the gateway and deploy a function, setting OPENFAAS_URL to the application IP address for "openfaas":

export OPENFAAS_URL=http://10.0.0.1:8080

These values can be overridden in the charm config using "admin_password" and "admin_username", but the defaults are admin/admin. Log in:

faas-cli login --password admin --username admin

Deploy and invoke the function:

faas-cli store deploy figlet

faas-cli invoke figlet <<< "juju"

List functions:

faas-cli list

Open the OpenFaaS UI:

echo $OPENFAAS_URL

WIP

The openfaas-queue-worker cannot be deployed because the operator framework expects a TCP port to be exposed, and the queue-worker is not a server component, but a pull-based queue subscriber.

(   
    cd openfaas-queue-worker
    charmcraft build && juju deploy ./openfaas-queue-worker.charm 
    cd ..
    
    juju relate openfaas-queue-worker nats
    )