Use Azure tags in Azure Kubernetes Service (AKS)

With Azure Kubernetes Service (AKS), you can set Azure tags on an AKS cluster and its related resources by using Azure Resource Manager, through the Azure CLI. For some resources, you can also use Kubernetes manifests to set Azure tags. Azure tags are a useful tracking resource for certain business processes, such as chargeback.

This article explains how to set Azure tags for AKS clusters and related resources.

Before you begin

It's a good idea to understand what happens when you set and update Azure tags with AKS clusters and their related resources. For example:

  • Tags set on an AKS cluster apply to all resources that are related to the cluster, but not the node pools. This operation overwrites the values of existing keys.
  • Tags set on a node pool apply only to resources related to that node pool. This operation overwrites the values of existing keys. Resources outside that node pool, including resources for the rest of the cluster and other node pools, are unaffected.
  • Public IPs, files, and disks can have tags set by Kubernetes through a Kubernetes manifest. Tags set in this way will maintain the Kubernetes values, even if you update them later by using another method. When public IPs, files, or disks are removed through Kubernetes, any tags that are set by Kubernetes are removed. Tags on those resources that aren't tracked by Kubernetes remain unaffected.

Prerequisites

  • The Azure CLI version 2.0.59 or later, installed and configured.

    To find your version, runĀ az --version. If you need to install it or update your version, seeĀ Install Azure CLI.

  • Kubernetes version 1.20 or later, installed.

Limitations

  • Azure tags have keys that are case-insensitive for operations, such as when you're retrieving a tag by searching the key. In this case, a tag with the specified key will be updated or retrieved regardless of casing. Tag values are case-sensitive.
  • In AKS, if multiple tags are set with identical keys but different casing, the tags are used in alphabetical order. For example, {"Key1": "val1", "kEy1": "val2", "key1": "val3"} results in Key1 and val1 being set.
  • For shared resources, tags aren't able to determine the split in resource usage on their own.

Add tags to the cluster

When you create or update an AKS cluster with the --tags parameter, the following are assigned the Azure tags that you've specified:

  • The AKS cluster
  • The route table that's associated with the cluster
  • The public IP that's associated with the cluster
  • The load balancer that's associated with the cluster
  • The network security group that's associated with the cluster
  • The virtual network that's associated with the cluster
  • The AKS managed kubelet msi associated with the cluster
  • The AKS managed addon msi associated with the cluster
  • The private DNS zone associated with the private cluster
  • The private endpoint associated with the private cluster

Note

Azure Private DNS only supports 15 tags. tag resources.

To create a cluster and assign Azure tags, run az aks create with the --tags parameter, as shown in the following command. Running the command creates a myAKSCluster in the myResourceGroup with the tags dept=IT and costcenter=9999.

Note

To set tags on the initial node pool, the node resource group, the virtual machine scale set, and each virtual machine scale set instance that's associated with the initial node pool, also set the --nodepool-tags parameter.

az aks create \
    --resource-group myResourceGroup \
    --name myAKSCluster \
    --tags dept=IT costcenter=9999 \
    --generate-ssh-keys

Important

If you're using existing resources when you're creating a new cluster, such as an IP address or route table, az aks create overwrites the set of tags. If you delete that cluster later, any tags set by the cluster will be removed.

Verify that the tags have been applied to the cluster and related resources. The cluster tags for myAKSCluster are shown in the following example:

$ az aks show -g myResourceGroup -n myAKSCluster --query '[tags]'
{
  "clusterTags": {
    "costcenter": "9999",
    "dept": "IT"
  }
}

To update the tags on an existing cluster, run az aks update with the --tags parameter. Running the command updates the myAKSCluster with the tags team=alpha and costcenter=1234.

az aks update \
    --resource-group myResourceGroup \
    --name myAKSCluster \
    --tags team=alpha costcenter=1234

Verify that the tags have been applied to the cluster. For example:

$ az aks show -g myResourceGroup -n myAKSCluster --query '[tags]'
{
  "clusterTags": {
    "costcenter": "1234",
    "team": "alpha"
  }
}

Important

Setting tags on a cluster by using az aks update overwrites the set of tags. For example, if your cluster has the tags dept=IT and costcenter=9999 and you use az aks update with the tags team=alpha and costcenter=1234, the new list of tags would be team=alpha and costcenter=1234.

Adding tags to node pools

You can apply an Azure tag to a new or existing node pool in your AKS cluster. Tags applied to a node pool are applied to each node within the node pool and are persisted through upgrades. Tags are also applied to new nodes that are added to a node pool during scale-out operations. Adding a tag can help with tasks such as policy tracking or cost estimation.

When you create or update a node pool with the --tags parameter, the tags that you specify are assigned to the following resources:

  • The node pool
  • The node resource group
  • The virtual machine scale set and each virtual machine scale set instance that's associated with the node pool

To create a node pool with an Azure tag, run az aks nodepool add with the --tags parameter. Running the following command creates a tagnodepool node pool with the tags abtest=a and costcenter=5555 in the myAKSCluster.

az aks nodepool add \
    --resource-group myResourceGroup \
    --cluster-name myAKSCluster \
    --name tagnodepool \
    --node-count 1 \
    --tags abtest=a costcenter=5555 \
    --no-wait

Verify that the tags have been applied to the tagnodepool node pool.

$ az aks show -g myResourceGroup -n myAKSCluster --query 'agentPoolProfiles[].{nodepoolName:name,tags:tags}'
[
  {
    "nodepoolName": "nodepool1",
    "tags": null
  },
  {
    "nodepoolName": "tagnodepool",
    "tags": {
      "abtest": "a",
      "costcenter": "5555"
    }
  }
]

To update a node pool with an Azure tag, run az aks nodepool update with the --tags parameter. Running the following command updates the tagnodepool node pool with the tags appversion=0.0.2 and costcenter=4444 in the myAKSCluster, which already has the tags abtest=a and costcenter=5555.

az aks nodepool update \
    --resource-group myResourceGroup \
    --cluster-name myAKSCluster \
    --name tagnodepool \
    --tags appversion=0.0.2 costcenter=4444 \
    --no-wait

Important

Setting tags on a node pool by using az aks nodepool update overwrites the set of tags. For example, if your node pool has the tags abtest=a and costcenter=5555, and you use az aks nodepool update with the tags appversion=0.0.2 and costcenter=4444, the new list of tags would be appversion=0.0.2 and costcenter=4444.

Verify that the tags have been updated on the nodepool.

$ az aks show -g myResourceGroup -n myAKSCluster --query 'agentPoolProfiles[].{nodepoolName:name,tags:tags}'
[
  {
    "nodepoolName": "nodepool1",
    "tags": null
  },
  {
    "nodepoolName": "tagnodepool",
    "tags": {
      "appversion": "0.0.2",
      "costcenter": "4444"
    }
  }
]

Add tags by using Kubernetes

You can apply Azure tags to public IPs, disks, and files by using a Kubernetes manifest.

For public IPs, use service.beta.kubernetes.io/azure-pip-tags under annotations. For example:

apiVersion: v1
kind: Service
metadata:
  annotations:
    service.beta.kubernetes.io/azure-pip-tags: costcenter=3333,team=beta
spec:
  ...

For files and disks, use tags under parameters. For example:

---
apiVersion: storage.k8s.io/v1
...
parameters:
  ...
  tags: costcenter=3333,team=beta
...

Important

Setting tags on files, disks, and public IPs by using Kubernetes updates the set of tags. For example, if your disk has the tags dept=IT and costcenter=5555, and you use Kubernetes to set the tags team=beta and costcenter=3333, the new list of tags would be dept=IT, team=beta, and costcenter=3333.

Any updates that you make to tags through Kubernetes will retain the value that's set through Kubernetes. For example, if your disk has tags dept=IT and costcenter=5555 set by Kubernetes, and you use the portal to set the tags team=beta and costcenter=3333, the new list of tags would be dept=IT, team=beta, and costcenter=5555. If you then remove the disk through Kubernetes, the disk would have the tag team=beta.