Azure Container Instances Connector for Kubernetes (experimental)

The Azure Container Instances Connector for Kubernetes allows Kubernetes clusters to deploy Azure Container Instances.

This enables on-demand and nearly instantaneous container compute, orchestrated by Kubernetes, without having VM infrastructure to manage and while still leveraging the portable Kubernetes API. This will allow you to utilize both VMs and container instances simultaneously in the same Kubernetes cluster, giving you the best of both worlds.

Please note this software is experimental and should not be used for anything resembling a production workload.

How does it Work

The ACI Connector roughly mimics the Kubelet interface by:

• Registering into the Kubernetes data plane as a Node with unlimited capacity
• Dispatching scheduled Pods to Azure Container Instances instead of a VM-based container engine

Once the connector is registered as a node named aci-connector, you can use nodeName: aci-connector in your Pod spec run the Pod via Azure Container Instances. Pods without this node name will continue to be scheduled normally. See below for instructions on how to use use the ACI Connector with the Kubernetes scheduler via taints and tolerations.

Requirements

1. A working az command-line client
2. A Kubernetes cluster with a working kubectl

Quickstart

1. Edit examples/aci-connector.yaml and supply environment variables
2. Run the ACI Connector with kubectl create -f examples/aci-connector.yaml
3. Wait for kubectl get nodes to display the aci-connector node
4. Run an NGINX pod via ACI using kubectl create -f examples/nginx-pod.yaml
5. Access the NGINX pod via its public address

Usage

Create a Service Principal

A service principal is required to allow the ACI Connector to create resources in your Azure subscription. You can create one using the az CLI using the instructions below.

Find your subscriptionId with the az CLI:

$ az account list -o table
Name                                             CloudName    SubscriptionId                        State    IsDefault
-----------------------------------------------  -----------  ------------------------------------  -------  -----------
Pay-As-You-Go                                    AzureCloud   12345678-9012-3456-7890-123456789012  Enabled  True

Use az to create a Service Principal that can perform operations on your subscription:

$ az ad sp create-for-rbac --role=Contributor --scopes /subscriptions/<subscription-id>
{
  "appId": "<redacted>",
  "displayName": "azure-cli-2017-07-19-19-13-19",
  "name": "http://azure-cli-2017-07-19-19-13-19",
  "password": "<redacted>",
  "tenant": "<redacted>"
}

Edit the examples/aci-connector.yaml and input environment variables using the values above:

• AZURE_CLIENT_ID: insert appId
• AZURE_CLIENT_KEY: insert password
• AZURE_TENANT_ID: insert tenant
• AZURE_SUBSCRIPTION_ID: insert subscriptionId

Create a Resource Group

The ACI Connector will create each container instance in a specified resource group. You can create a new resource group with:

$ az group create -n aci-test -l westus
{
  "id": "/subscriptions/<subscriptionId>/resourceGroups/aci-test",
  "location": "westus",
  "managedBy": null,
  "name": "aci-test",
  "properties": {
    "provisioningState": "Succeeded"
  },
  "tags": null
}

Edit the examples/aci-connector.yaml and put the name of the resource group into the ACI_RESOURCE_GROUP environment variable.

Install the ACI Connector

$ kubectl create -f examples/aci-connector.yaml 
pod "aci-connector" created

$ kubectl get nodes -w
NAME                        STATUS                     AGE       VERSION
aci-connector               Ready                      3s        1.6.6
k8s-agentpool1-31868821-0   Ready                      5d        v1.7.0
k8s-agentpool1-31868821-1   Ready                      5d        v1.7.0
k8s-agentpool1-31868821-2   Ready                      5d        v1.7.0
k8s-master-31868821-0       Ready,SchedulingDisabled   5d        v1.7.0

Install the NGINX example

$ kubectl create -f examples/nginx-pod.yaml 
pod "nginx" created

$ kubectl get po -w -o wide
NAME          READY     STATUS    RESTARTS   AGE       IP             NODE
aci-connector 1/1       Running   0          44s       10.244.2.21    k8s-agentpool1-31868821-2
nginx         1/1       Running   0          31s       13.88.27.150   aci-connector

Note the pod is scheduled on the aci-connector node. It should now be accessible at the public IP listed.

Using the Kubernetes scheduler

The example in nginx-pod hard codes the node name, but you can also use the Kubernetes scheduler.

The virtual aci node, has a taint (azure.com/aci) with a default effect of NoSchedule. This means that by default Pods will not schedule onto the aci node unless they are explicitly placed there.

However, if you create a Pod that tolerates this taint, it can be scheduled to the aci node by the Kubernetes scheduler.

Here is an example of Pod with this toleration.

To use this Pod, you can simply:

$ kubectl create -f examples/nginx-pod-toleration.yaml

Note that if you have other nodes in your cluster then this Pod may not necessarily schedule onto the Azure Container Instances.

To force a Pod onto Azure Container Instances, you can either explicitly specify the NodeName as in the first example, or you can delete all of the other nodes in your cluster using kubectl delete nodes <node-name>. A third option is to fill your cluster with other workloads, then the scheduler will be obligated to schedule work to the Azure Container Instance API.

Development Instructions

Local Development

<edit source>
$ make clean
$ make build
$ node connector.js

Docker Development

make docker-build
docker tag <local-image> <remote-image>
docker push <remote-image>

Then edit examples/aci-connector.yaml to point to the remote-image.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.