Enable native sidecar mode for Istio-based service mesh add-on in Azure Kubernetes Service (AKS) (preview)

Article
08/01/2024

Kubernetes native sidecar aims to provide a more robust and user-friendly way to incorporate sidecar patterns into Kubernetes applications, improving efficiency, reliability, and simplicity.

Native sidecar is a good fit for Istio. It offers several benefits, such as simplified sidecar management. Additionally, it improves reliability and coordination. It also optimizes resources and enhances operational efficiency.

Starting from Kubernetes version 1.29, sidecar containers feature is turned on for AKS. With this change, Istio native sidecar mode can be used with the Istio add-on for AKS.

This article walks through how to enable native sidecar mode for Istio based service mesh on AKS.

Before you begin

az feature register --namespace Microsoft.ContainerService --name IstioNativeSidecarModePreview

Verify the registration status through az feature show.
```
az feature show --namespace Microsoft.ContainerService --name IstioNativeSidecarModePreview
```
It takes a few minutes for the status to show Registered.
When the status reflects Registered, refresh the registration of the Microsoft.ContainerService resource provider through az provider register.
```
az provider register --namespace Microsoft.ContainerService
```

On an existing cluster

Check versions

Check that the AKS cluster's Kubernetes control plane version is 1.29 or higher using az aks show.
```
az aks show --resource-group $RESOURCE_GROUP --name $CLUSTER -o json | jq ".kubernetesVersion"
```
If the control plane version is too old, upgrade Kubernetes control plane.
Make sure node pools runs 1.29 or newer version and power state is running.
```
az aks show --resource-group $RESOURCE_GROUP --name $CLUSTER -o json | jq ".agentPoolProfiles[] | { currentOrchestratorVersion, powerState}"
```
Caution

Native sidecar mode requires both Kubernetes control plane and data plane on 1.29+. Make sure all your nodes have been upgraded to 1.29 before enabling native sidecar mode. Otherwise, sidecars will not work as expected.

If any node pool version is too old, upgrade-node-image to 1.29 or newer version.
Make sure Istio add-on is on asm-1-20 or newer revision.
```
az aks show --resource-group $RESOURCE_GROUP --name $CLUSTER -o json | jq ".serviceMeshProfile.istio.revisions"
```
If istiod is too old, upgrade to asm-1-20 or newer by following the steps in Istio upgrade.

Check native sidecar feature status on Istio control plane

AKS cluster needs to be reconciled with az aks update command.

az aks update --resource-group $RESOURCE_GROUP --name $CLUSTER

When native sidecar mode is enabled, environment variable ENABLE_NATIVE_SIDECARS appears with value true in Istio's control plane pod template. Use the following command to check istiod deployment.

kubectl get deployment -l app=istiod -n aks-istio-system -o json | jq '.items[].spec.template.spec.containers[].env[] | select(.name=="ENABLE_NATIVE_SIDECARS")'

Restart workloads

Once Istio control plane is ready, do a rolling restart of workloads to let istiod inject native sidecars.

for ns in $(kubectl get ns -l istio.io/rev -o=jsonpath='{.items[0].metadata.name}'); do
  kubectl rollout restart deployments -n $ns
done

For deployments having istio sidecars injected with istioctl kube-inject, you need to reinject sidecars.

Check sidecar injection

If native side mode is successfully enabled, istio-proxy container is shown as an init container. Use the following command to check sidecar injection:

kubectl get pods -o "custom-columns=NAME:.metadata.name,INIT:.spec.initContainers[*].name,CONTAINERS:.spec.containers[*].name"

istio-proxy container should be shown as an init container.

NAME                     INIT                     CONTAINERS
sleep-7656cf8794-5b5j4   istio-init,istio-proxy   sleep

Create a new cluster

When creating a new AKS cluster with az aks create command, choose a version 1.29 or newer, istio asm-1-20 or newer. The new cluster should have native sidecar mode turned on automatically.

az aks create \
    --resource-group $RESOURCE_GROUP \
    --name $CLUSTER \
    --enable-asm \
    --kubernetes-version 1.29 \
    --revision asm-1-20 \
    --generate-ssh-keys    
    ...

Next steps

Deploy external or internal ingresses for Istio service mesh add-on.

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