Using OpenFaaS on AKS on Azure Stack HCI

OpenFaaS is a framework for building serverless functions through the use of containers. As an open source project, it has gained large-scale adoption within the community. This document details installing and using OpenFaas on Kubernetes cluster running on AKS on Azure Stack HCI.

Prerequisites

In order to complete the steps within this article, you need the following.

  • Basic understanding of Kubernetes.
  • An AKS on Azure Stack HCI cluster with at least one Linux worker node that's up and running.
  • You have configured your local kubectl environment to point to your AKS on Azure Stack HCI cluster. You can use the Get-AksHciCredential PowerShell command to access your cluster using kubectl.
  • Helm v3 command line and prerequisites installed.
  • Azure CLI can also be used to run commands, if you prefer this to PowerShell.
  • Git command-line tools installed on your system
  • Install the OpenFaaS CLI. See the OpenFaaS CLI documentation for installation options

Important

Helm is intended to run on Linux nodes. If you have Windows Server nodes in your cluster, you must ensure that Helm pods are only scheduled to run on Linux nodes. You also need to ensure that any Helm charts you install are also scheduled to run on the correct nodes. The commands in this article use node-selectors to make sure pods are scheduled to the correct nodes, but not all Helm charts may expose a node selector. You can also consider using other options on your cluster, such as [taints](./adapt-apps-mixed-os-clusters.md#taints-and -tolerations).

Add the OpenFaaS helm chart repo

With your kubeconfig file in hand, open your console to start the deployment process. If you're running on Windows, downloading and running Git Bash is the easiest way to follow along. From there, to begin, OpenFaaS maintains its own helm charts to keep up to date with all the latest changes:

helm repo add openfaas https://openfaas.github.io/faas-netes/
helm repo update

Deploy OpenFaaS

As a best practice, OpenFaaS and OpenFaaS functions should be stored in their own Kubernetes namespace.

Create a namespace for the OpenFaaS system and functions:

kubectl apply -f https://raw.githubusercontent.com/openfaas/faas-netes/master/namespaces.yml

Generate a password for the OpenFaaS UI Portal and REST API:

# generate a random password
PASSWORD=$(head -c 12 /dev/urandom | shasum| cut -d' ' -f1)

kubectl -n openfaas create secret generic basic-auth \
--from-literal=basic-auth-user=admin \
--from-literal=basic-auth-password="$PASSWORD"

You can get the value of the secret with echo $PASSWORD.

The password we create here will be used by the helm chart to enable basic authentication on the OpenFaaS Gateway, which is exposed externally through a LoadBalancer.

A Helm chart for OpenFaaS is included in the cloned repository. Use this chart to deploy OpenFaaS into your AKS cluster.

helm upgrade openfaas --install openfaas/openfaas \
    --namespace openfaas  \
    --set basic_auth=true \
    --set functionNamespace=openfaas-fn \
    --set serviceType=LoadBalancer

Output:

NAME:   openfaas
LAST DEPLOYED: Fri May 14 18:35:47 2021
NAMESPACE: openfaas
STATUS: deployed
REVISION: 1
TEST SUITE: None

To verify that OpenFaas has started, run the following command:

kubectl --namespace=openfaas get deployments -l "release=openfaas, app=openfaas"

A public IP address is created for accessing the OpenFaaS gateway. To retrieve this IP address, use the kubectl get service command. It may take a minute for the IP address to be assigned to the service.

kubectl get service -l component=gateway --namespace openfaas

Output:

NAME               TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)          AGE
gateway            ClusterIP      10.110.205.41  <none>         8080/TCP         7m
gateway-external   LoadBalancer   10.107.51.110  192.168.0.152  8080:32029/TCP   7m

To test the OpenFaaS system, browse to the external IP address on port 8080, http://192.168.0.152:8080 in this example. You will be prompted to log in. To fetch your password, enter echo $PASSWORD.

OpenFaaS UI

Set $OPENFAAS_URL to the External-IP found above.

Log in with your console. Note, if running in Git Bash on Windows, you may need to use faas-cli instead of ./faas-cli in the command below.

export OPENFAAS_URL=http://192.168.0.152:8080
echo -n $PASSWORD | ./faas-cli login -g $OPENFAAS_URL -u admin --password-stdin

Create first function

Now that OpenFaaS is operational, create a function using the OpenFaas portal.

Click on Deploy New Function and search for Figlet. Select the Figlet function, and click Deploy.

Screenshot shows the Deploy A New Function dialog box with the text figlet on the search line.

Use curl to invoke the function. Replace the IP address in the following example with that of your OpenFaas gateway.

curl -X POST http://192.168.0.152:8080/function/figlet -d "Hello Azure"

Output:

 _   _      _ _            _
| | | | ___| | | ___      / \    _____   _ _ __ ___
| |_| |/ _ \ | |/ _ \    / _ \  |_  / | | | '__/ _ \
|  _  |  __/ | | (_) |  / ___ \  / /| |_| | | |  __/
|_| |_|\___|_|_|\___/  /_/   \_\/___|\__,_|_|  \___|

Clean up resources

When you deploy a Helm chart, a number of Kubernetes resources are created. These resources include pods, deployments, and services. To clean up these resources, use the [helm uninstall][helm-cleanup] command and specify your release name, as found in the previous helm list command.

helm uninstall openfaas

The following example shows the release named openfaas has been uninstalled:

release "openfaas" uninstalled

Next Steps

You can continue to learn with the OpenFaaS workshop through a set of hands-on labs that cover topics such as how to create your own GitHub bot, consuming secrets, viewing metrics, and auto-scaling.