Standard Walkthrough

You will need Azure CLI installed and a Kubernetes cluster running on Azure, either managed by AKS or provisioned with AKS Engine.

Run the following commands to set Azure-related environment variables and login to Azure via az login:

export SUBSCRIPTION_ID="<SubscriptionID>"

# login as a user and set the appropriate subscription ID
az login
az account set -s "${SUBSCRIPTION_ID}"

export RESOURCE_GROUP="<AKSResourceGroup>"
export CLUSTER_NAME="<AKSClusterName>"

# for this demo, we will be deploying a user-assigned identity to the AKS node resource group
export IDENTITY_RESOURCE_GROUP="$(az aks show -g ${RESOURCE_GROUP} -n ${CLUSTER_NAME} --query nodeResourceGroup -otsv)"
export IDENTITY_NAME="demo"

For AKS clusters, there are two resource groups that you need to be aware of - the resource group where you deploy your AKS cluster to (denoted by the environment variable RESOURCE_GROUP), and the node resource group (MC_<AKSResourceGroup>_<AKSClusterName>_<AKSClusterLocation>). The latter contains all of the infrastructure resources associated with the cluster like VM/VMSS and VNet. Depending on where you deploy your user-assigned identities, you might need additional role assignments. Please refer to Role Assignment for more information. For this demo, it is recommended to deploy the demo identity to your node resource group (the one with MC_ prefix).

1. Deploy aad-pod-identity

Deploy aad-pod-identity components to an RBAC-enabled cluster:

kubectl apply -f https://raw.githubusercontent.com/Azure/aad-pod-identity/master/deploy/infra/deployment-rbac.yaml

# For AKS clusters, deploy the MIC and AKS add-on exception by running -
kubectl apply -f https://raw.githubusercontent.com/Azure/aad-pod-identity/master/deploy/infra/mic-exception.yaml

Deploy aad-pod-identity components to a non-RBAC cluster:

kubectl apply -f https://raw.githubusercontent.com/Azure/aad-pod-identity/master/deploy/infra/deployment.yaml

# For AKS clusters, deploy the MIC and AKS add-on exception by running -
kubectl apply -f https://raw.githubusercontent.com/Azure/aad-pod-identity/master/deploy/infra/mic-exception.yaml

Deploy aad-pod-identity using Helm 3:

helm repo add aad-pod-identity https://raw.githubusercontent.com/Azure/aad-pod-identity/master/charts
helm install aad-pod-identity aad-pod-identity/aad-pod-identity

For a list of overwritable values when installing with Helm, please refer to this section.

Important: For AKS clusters with limited egress traffic, Please install aad-pod-identity in kube-system namespace using the helm charts.

helm install aad-pod-identity aad-pod-identity/aad-pod-identity --namespace=kube-system

2. Create an identity on Azure

Create an identity on Azure and store the client ID and resource ID of the identity as environment variables:

az identity create -g ${IDENTITY_RESOURCE_GROUP} -n ${IDENTITY_NAME}
export IDENTITY_CLIENT_ID="$(az identity show -g ${IDENTITY_RESOURCE_GROUP} -n ${IDENTITY_NAME} --query clientId -otsv)"
export IDENTITY_RESOURCE_ID="$(az identity show -g ${IDENTITY_RESOURCE_GROUP} -n ${IDENTITY_NAME} --query id -otsv)"

3. Deploy AzureIdentity

Create an AzureIdentity in your cluster that references the identity you created above:

cat <<EOF | kubectl apply -f -
apiVersion: "aadpodidentity.k8s.io/v1"
kind: AzureIdentity
metadata:
  name: ${IDENTITY_NAME}
spec:
  type: 0
  resourceID: ${IDENTITY_RESOURCE_ID}
  clientID: ${IDENTITY_CLIENT_ID}
EOF

Set type: 0 for user-assigned MSI, type: 1 for Service Principal with client secret, or type: 2 for Service Principal with certificate. For more information, see here.

4. (Optional) Match pods in the namespace

For matching pods in the namespace, please refer to the namespaced documentation.

5. Deploy AzureIdentityBinding

Create an AzureIdentityBinding that reference the AzureIdentity you created above:

cat <<EOF | kubectl apply -f -
apiVersion: "aadpodidentity.k8s.io/v1"
kind: AzureIdentityBinding
metadata:
  name: ${IDENTITY_NAME}-binding
spec:
  azureIdentity: ${IDENTITY_NAME}
  selector: ${IDENTITY_NAME}
EOF

6. Deployment and Validation

For a pod to match an identity binding, it needs a label with the key aadpodidbinding whose value is that of the selector: field in the AzureIdentityBinding. Deploy a pod that validates the functionality:

cat << EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: demo
  labels:
    aadpodidbinding: $IDENTITY_NAME
spec:
  containers:
  - name: demo
    image: mcr.microsoft.com/oss/azure/aad-pod-identity/demo:v1.8.2
    args:
      - --subscription-id=${SUBSCRIPTION_ID}
      - --resource-group=${IDENTITY_RESOURCE_GROUP}
      - --identity-client-id=${IDENTITY_CLIENT_ID}
  nodeSelector:
    kubernetes.io/os: linux
EOF

mcr.microsoft.com/oss/azure/aad-pod-identity/demo is an image that demonstrates the use of AAD pod identity. The source code can be found here.

To verify that the pod is indeed using the identity correctly:

kubectl logs demo

If successful, the log output would be similar to the following output:

I0510 18:16:53.042124       1 main.go:128] curl -H Metadata:true "http://169.254.169.254/metadata/instance?api-version=2017-08-01": {"compute":{"location":"westus2","name":"aks-nodepool1-17529566-vmss_1","offer":"aks","osType":"Linux","placementGroupId":"877d5750-2bed-43dd-bad6-62e4f3b58a3c","platformFaultDomain":"0","platformUpdateDomain":"1","publisher":"microsoft-aks","resourceGroupName":"MC_chuwon_chuwon_westus2","sku":"aks-ubuntu-1804-gen2-2021-q1","subscriptionId":"2d31b5ab-0ddc-4991-bf8d-61b6ad196f5a","tags":"aksEngineVersion:v0.47.0-aks-gomod-b4-aks;creationSource:aks-aks-nodepool1-17529566-vmss;orchestrator:Kubernetes:1.18.14;poolName:nodepool1;resourceNameSuffix:17529566","version":"2021.01.28","vmId":"4fc9f60c-170c-4e76-84ff-81c6c0cecea1","vmSize":"Standard_DS2_v2"},"network":{"interface":[{"ipv4":{"ipAddress":[{"privateIpAddress":"10.240.0.5","publicIpAddress":""}],"subnet":[{"address":"10.240.0.0","prefix":"16"}]},"ipv6":{"ipAddress":[]},"macAddress":"000D3AFE98BF"}]}}
I0510 18:17:04.463222       1 main.go:75] successfully acquired a service principal token from http://169.254.169.254/metadata/identity/oauth2/token
I0510 18:17:04.474588       1 main.go:100] successfully acquired a service principal token from http://169.254.169.254/metadata/identity/oauth2/token using a user-assigned identity (a9979fb6-6655-4612-95c9-7e4d0c83001b)
I0510 18:17:04.474610       1 main.go:50] Try decoding your token <JWT token> at https://jwt.io

Once you are done with the demo, clean up your resources:

kubectl delete pod demo
kubectl delete azureidentity ${IDENTITY_NAME}
kubectl delete azureidentitybinding ${IDENTITY_NAME}-binding
az role assignment delete --id ${IDENTITY_ASSIGNMENT_ID}
az identity delete -g ${IDENTITY_RESOURCE_GROUP} -n ${IDENTITY_NAME}

Uninstall Notes

The NMI pods modify the nodes' [iptables] to intercept calls to IMDS endpoint within a node. This allows NMI to insert identities assigned to a pod before executing the request on behalf of the caller.

These iptables entries will be cleaned up when the pod-identity pods are uninstalled. However, if the pods are terminated for unexpected reasons, the iptables entries can be removed with these commands on the node:

# remove the custom chain reference
iptables -t nat -D PREROUTING -j aad-metadata

# flush the custom chain
iptables -t nat -F aad-metadata

# remove the custom chain
iptables -t nat -X aad-metadata