OpenFaaS

OpenFaaS is an open-source platform for running functions (FaaS) on top of Kubernetes. It simplifies the deployment of small code units that execute on demand or in response to events.

At its core, OpenFaaS follows the Function as a Service (FaaS) model: you write a function, package it into a Docker image, and OpenFaaS handles scaling, networking, and lifecycle management.

It offers a user-friendly web interface and a command-line tool called faas-cli. You can write functions in popular languages such as Python, Node.js, Go, and others using pre-built templates.

The complete documentation for OpenFaaS on Kubernetes is available on the official website.

Installing the Addon

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To install OpenFaaS:

1. Go to the Kubernetes section and click on your cluster.
2. In the Addons tab, click OpenFaaS.
3. In the Configuration window, find the ingress section and enable it by setting enabled: true. Also, specify your domain in the host parameter. This will simplify access to the dashboard and allow usage of faas-cli. If you enable ingress, you can disable exposeServices, which is used by default.
4. Once parameters are set, click Install and wait for the installation to finish.

To verify everything is running, check the status of pods in the openfaas-fn namespace:

kubectl get pods -n openfaas-fn

Example output:

NAME                            READY   STATUS    RESTARTS      AGE
alertmanager-57767d864c-hdqdn   1/1     Running   0             19h
gateway-5f9c4b5754-ksr6x        2/2     Running   1 (19h ago)   19h
nats-6ddf479847-dxr2g           1/1     Running   0             19h
prometheus-6cbd946f66-wqdf8     1/1     Running   0             19h
queue-worker-57c7479989-bw282   1/1     Running   0             19h

If all pods are in Running status, the installation was successful.

Installing the CLI

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To work with OpenFaaS from the terminal, you need the faas-cli tool. It allows you to create functions, build and push images, deploy them to the cluster, invoke functions, and check their status.

It is available for Linux, macOS, and Windows. Use the following commands to install it:

Linux/macOS

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

macOS

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

Or, via Homebrew:

brew install faas-cli

Windows (PowerShell)

$version = (Invoke-WebRequest "https://api.github.com/repos/openfaas/faas-cli/releases/latest" | ConvertFrom-Json)[0].tag_name

(New-Object System.Net.WebClient).DownloadFile("https://github.com/openfaas/faas-cli/releases/download/$version/faas-cli.exe", "faas-cli.exe")

Verify the installation:

faas-cli version

Example Usage

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In this example, we will:

• Deploy the OpenFaaS addon.
• Bind a domain for easy dashboard access and CLI use.
• Deploy a function from the built-in store.
• Create and deploy a custom function using Docker Hub.

Requirements:

• A domain or subdomain for OpenFaaS access.
• Installed Nginx Ingress addon.
• A Docker Hub account (for custom functions).
• Installed faas-cli and Docker.

Deploying the Addon

Go to the control panel and install the OpenFaaS addon. In the Configuration section, enable ingress by setting enabled: true and specifying your domain in the host field. Then start the installation.

Creating a Load Balancer

Create a loadbalancer.yaml manifest:

apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx-lb
  namespace: ingress-nginx
spec:
  selector:
    app.kubernetes.io/name: ingress-nginx
  type: LoadBalancer
  ports:
    - name: http
      port: 80
      targetPort: 80
      appProtocol: k8s.hostman.com/proto-http
    - name: https
      port: 443
      targetPort: 443
      appProtocol: k8s.hostman.com/proto-https

Apply it:

kubectl apply -f loadbalancer.yaml

Set the balancer’s IP as the A record of your domain. If you're using Hostman NS servers, just select the newly created load balancer. Otherwise, get its IP manually:

kubectl get svc --all-namespaces --field-selector spec.type=LoadBalancer

The IP will be under the EXTERNAL-IP column.

Visit the domain you configured—a basic auth prompt will appear.

Use the login admin and retrieve the password using:

kubectl -n openfaas-fn get secret basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode

After logging in, the dashboard will open.

OpenFaaS Dashboard

Working with Functions

Let’s move on to using functions. We’ll install a function from the built-in OpenFaaS store.

First, log in via the CLI. This will allow you to run commands related to function management:

faas-cli login \
  --gateway http://<domain> \
  --username admin \
  --password <password>

Where:

• domain — the address specified during OpenFaaS installation;
• admin — the default username;
• password — the password can be retrieved with the following command:

kubectl -n openfaas-fn get secret basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode

Now install the figlet function, which converts text into ASCII art:

faas-cli store deploy figlet \
  --gateway http://<domain>

Make sure the function has been installed:

faas-cli list \
  --gateway http://<domain>

The list will now contain the figlet function with a status of Ready.

Invoke the function and pass a string as input:

echo "Hostman" | faas-cli invoke figlet \
  --gateway http://<domain>

You’ll receive ASCII art with the given text in response.

Now let’s go over deploying a custom function. Choose a template:

faas-cli template store list

Create a new function based on the desired template—for example, python3-http:

faas-cli new hello-k8s --lang python3-http

The following will be created:

• hello-k8s/handler.py — the function code;
• stack.yaml — the function manifest.

Before building, edit the stack.yaml file and specify the path to your Docker Hub image. For example:

functions:
  hello-k8s:
    lang: python3-http
    handler: ./hello-k8s
    image: dockerhubuser/hello-k8s:latest

In the image field, specify your Docker Hub username and the image name. Note that OpenFaaS Community Edition only supports public images.

Build the image:

faas-cli build -f stack.yaml

After the image is built, push it to Docker Hub:

faas-cli push -f stack.yaml

Finally, deploy the function to your cluster:

faas-cli deploy -f stack.yaml \
  --gateway http://<domain>

After running the command, you’ll get a link to access the function.

Open the link. You should see the message "Hello from OpenFaaS!".