---

Azure Kubernetes Services (AKS) - Part 07

AKS based event-driven autoscaling using KEDA with Function App Docker Container

High Level Architecture Diagram:

Configuration Flow :

1. Provision the environment using Azure Terraform
2. Create a Azure Function App Container
3. Deploy the container to Dockerhub or Azure Container Registry
4. Deploy KEDA to aks cluster
5. Save data in the Azure Storage Queue, trigger from a web app or console app
6. View the event driven autoscaling using KEDA

Prerequisite - Environment setup

• Install Docker for Windows https://docs.docker.com/docker-for-windows/install/
• Install VS2019 Community Edition https://visualstudio.microsoft.com/vs/compare/
• Install NodeJS https://nodejs.org/en/download/

---

1. Provision the environment using Azure Terraform

terraform init
terraform plan
terraform apply

Connect to AKS

# Get K8S Credentials
az aks get-credentials --resource-group Env-aks-KEDA-RG --name az-k8s

# Enable addOn
az aks enable-addons --addons kube-dashboard --resource-group Env-aks-KEDA-RG --name az-k8s

# Open Kubernetes Dash Board
az aks browse --resource-group Env-aks-KEDA-RG --name az-k8s
   

kubectl get nodes

---

2. Create a Azure Function App Container

Open a commandline, run as Administrator

func init --docker
select > dotnet

func new functionapp01
Select  > queuetrigger

Add the Azure Storage Queue Access key to local.settings.json file from the FunctionApp project.

  "azstorageaccnt01_connection": "DefaultEndpointsProtocol=https;AccountName=azstorageaccnt01;AccountKey=s9FysFde5b7D5GbrCWsgyYqLNNxw65xvFqdler10aibcvLC8sL2a0On96wQ/j08gxNSs65mBHpKAQ6nMB/CG6g==;EndpointSuffix=core.windows.net"

In the code, update the the QueueTrigger details from functionapp01.cs file. The queue name must match the queue name created by the terraform

public static void Run([QueueTrigger("az-strorage-queue01", Connection = "azstorageaccnt01_connection")]string myQueueItem, ILogger log)

View the docker file

FROM microsoft/dotnet:2.2-sdk AS installer-env

COPY . /src/dotnet-function-app
RUN cd /src/dotnet-function-app && \
    mkdir -p /home/site/wwwroot && \
    dotnet publish *.csproj --output /home/site/wwwroot

# To enable ssh & remote debugging on app service change the base image to the one below
# FROM mcr.microsoft.com/azure-functions/dotnet:2.0-appservice 
FROM mcr.microsoft.com/azure-functions/dotnet:2.0
ENV AzureWebJobsScriptRoot=/home/site/wwwroot \
    AzureFunctionsJobHost__Logging__Console__IsEnabled=true

COPY --from=installer-env ["/home/site/wwwroot", "/home/site/wwwroot"]

Build the functionApp Container

  docker login
  docker build -t functionapp01 .

---

3. Deploy the container to Azure Container Registry

Using Azure Container Registry

# Login to ACR
  az acr login --name azacr10

# Tag container image
  az acr show --name azacr10 --query loginServer --output table

docker images

# Tag the weblinux1 image with the loginServer of container registry
  docker tag fucntionapp01 azacr10.azurecr.io/fucntionapp01:v1


# Push image to Azure Container Registry
  docker push azacr10.azurecr.io/fucntionapp01:v1

# List images in Azure Container Registry
  az acr repository list --name azacr10 --output table

# View the tags for a specific images
  az acr repository show-tags --name azacr10 --repository fucntionapp01 --output table
 

---

4. Install KEDA to aks cluster and deploy the function app container

Install KEDA

func kubernetes install --namespace keda --validate=false

Deploy the function App from Azure Container Registry to aks

- Login to ACR
 az acr login --name azacr10
 
# func kubernetes deploy --name <name-of-function-deployment> --registry <acr-login-server>
  func kubernetes deploy --name functionapp01 --registry azacr10.azurecr.io

Deploy the function App from DockerHub to aks

- Login to Docker Hub
  docker login

- Deploy the function App container
# func kubernetes deploy --name <name-of-function-deployment> --registry <container-registry-username>
  func kubernetes deploy --name functionapp01 --registry gbbuenaflor

Check the deployment

kubectl get deploy

---

5. Save data in the Azure Storage Queue, trigger from a web app or console app

Use the code to save messages in the Azure Queue

- In Web App, you normally save shopping cart data to the queue

- In Console App, you can iterate and save data to the queue manually

 string azstorageaccnt01_connection = "DefaultEndpointsProtocol=https;AccountName=azstorageaccnt01;AccountKey=s9FysFde5b7D5GbrCWsgyYqLNNxw65xvFqdler10aibcvLC8sL2a0On96wQ/j08gxNSs65mBHpKAQ6nMB/CG6g==;EndpointSuffix=core.windows.net";

            CloudStorageAccount storageAccount = CloudStorageAccount.Parse(azstorageaccnt01_connection);
            CloudQueueClient cloudQueueClient = storageAccount.CreateCloudQueueClient();
            CloudQueue cloudQueue = cloudQueueClient.GetQueueReference("az-strorage-queue01"); //name of storage queue

            // Line below for Testing only , In Web App, you normally save shopping cart data to the queue
            for (int i = 0; i < 30000; i++)
            {
                CloudQueueMessage queueMessage = new CloudQueueMessage("New Data: " + System.DateTime.Now.ToString()); //message to write in the queue

                cloudQueue.AddMessage(queueMessage);
                Console.WriteLine("Message:" + i.ToString());

            }

---

6. View the event driven autoscaling using KEDA

View the function app deployment using acr

View the function app deployment using dockerhub

View the autoscaling, the number of pods and number of deployments within aks

Scale Up

Scale Down

---

Microsoft Azure Container Ecosystem - "nugget series" > Click this Link

Note: My Favorite -> Microsoft :D