Introduction

This repo provides a Helm chart to deploy Azure Pipelines agents as containers to an Azure Kubernetes Service (AKS) cluster. A Dockerfile for the Azure Pipelines agent is also provided as well as guidance on how to create the AKS cluster.

Prerequisites

• Docker
• Azure CLI
• Helm
• An Azure DevOps organization
• An Azure subscription

Create an Azure DevOps personal access token (PAT)

Create a personal access token with the Agent Pools(read, manage) scope following these instructions. You will have to provide later this token to the azpToken value of the helm chart.

Create an Azure Pipelines agent pool

Create a new agent pool foolowing these instructions. Your azure pipelines agents will join this pool later on.

Customize, build and publish the docker image

The Dockerfile available at dockeragent\ubuntu\16.04\ contains the basic tools needed to run the Azure Pipelines agent on Linux (as documented here) but feel free to customize it with any aditional tools you might need. Then, you will build and publish the image to Docker Hub (if you don't have a Docker ID you can create one for free here).

Run the following commands in a command prompt to build and publish your image, replacing yourdockerid with your Docker ID:

docker build -t yourdockerid/azpagent:ubuntu-16.04 ./dockeragent/ubuntu/16.04
docker login
docker push yourdockerid/azpagent:ubuntu-16.04

You could also publish your image to a private docker registry like Azure Container Registry but you'll need to update the helm chart to pass the appropriate image pull secret.

Create the AKS cluster

Run the following Azure CLI commands in a command prompt replacing <Azure subscription name>, <resource group name>, <resource group location> and <cluster name> with appropriate values for your subscription, resource group, location and kubernetes cluster:

az login
az account set --subscription <Azure subscription name>
az group create --name <resource group name> --location <resource group location>
az aks create -g <resource group name> -n <cluster name> --generate-ssh-keys

Chart parameters

The following table lists the configurable parameters of the azp-agent chart and their default values.

Parameter	Description	Default
image.repository	azp-agent image	nil (must be provided during installation)
image.tag	Specify image tag	nil (must be provided during installation)
image.pullSecrets	Specify image pull secrets	nil (does not add image pull secrets to deployed pods)
image.pullPolicy	Image pull policy	Always
replicas	Number of azp-agent instaces started	3
resources.disk	Size of the disk attached to the agent	50Gi
resources.storageclass	Specify storageclass used in kubernetes	default
resources.requests	CPU/Memory requests	nil
resources.limits	CPU/Memory limits	nil
azpUrl	The URL of the Azure DevOps instance	nil (must be provided during installation)
azpToken	Azure DevOps personal access token	nil (must be provided during installation)
azpPool	Azure Pipelines agent pool name	nil (must be provided during installation)
azpAgentName	Azure Pipelines agent name	azp-agent
azpWorkspace	Azure Pipelines agent workspace	/workspace
extraEnv	Extra environment variables on the azp-agent container	nil
cleanRun	Kill and restart azp-agent container on completion of a pipeline run (completely resets the environment)	true
volumes	An array of custom volumes to attach to the azp-agent pod	nil
volumeMounts	volumeMounts to the azp-agent container as referenced in volumes	nil
nodeSelector	assign pods to nodes based on this label	nil

Installing the chart

The chart can be installed with the following command:

helm install --set image.repository=<IMAGE REPO> --set image.tag:<IMAGE TAG> --set azpToken=<AZP TOKEN> --set azpUrl=<AZP URL> --set azpPool=<AZP POOL> -f helm-chart\azp-agent\values.yaml helm-chart\azp-agent azp-agent helm-chart\azp-agent

Example:

helm install --set image.repository=julioc/azpagent --set image.tag=ubuntu-16.04 --set azpToken=<TOKEN HERE> --set azpUrl=https://dev.azure.com/julioc --set azpPool=MyPool -f helm-chart\azp-agent\values.yaml azp-agent helm-chart\azp-agent

It may take some time to stand up the pods but eventually your deployment should look like this:

kubectl get pods
NAME           READY     STATUS    RESTARTS   AGE
azp-agent-0   1/1       Running   0          1m
azp-agent-1   1/1       Running   0          1m
azp-agent-2   1/1       Running   0          1m

Scaling up the number of agents

You can scale up (or down) the number of pipeline agents by either using kubectl scale:

kubectl scale statefulset/azp-agent --replicas 10

Or by running a helm upgrade with the replicas parameter:

helm upgrade --install --set image.repository=julioc/azpagent --set image.tag=ubuntu-16.04 --set azpToken=<TOKEN HERE> --set azpUrl=https://dev.azure.com/julioc --set azpPool=MyPool --set replicas=10 -f helm-chart\azp-agent\values.yaml azp-agent helm-chart\azp-agent