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config.md

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Config

We can use the config command to configure node information for kubectl-aks commands. This allows ease of switching between different nodes and persisting the configuration. Nodes can be configured either specifying the --node or --id or VMSS instance information (--subscription, --node-resource-group, --vmss, --instance-id). All three options are mutually exclusive:

$ kubectl aks config --help
Manage configuration

Usage:
  kubectl-aks config [command]

Available Commands:
  set-node           Set a given node in the configuration
  show               Show the configuration
  unset-all          Unset all nodes in the configuration
  unset-current-node Unset the current node in the configuration
  unset-node         Unset a given node in the configuration
  use-node           Set the current node in the configuration

Flags:
  -h, --help      help for config
  -v, --verbose   Verbose output.

Use "kubectl-aks config [command] --help" for more information about a command.

As an example, we set a couple of nodes in the configuration (using VMSS instance information) and then switch between them:

$ kubectl aks config set-node node1 --subscription mySubID --node-resource-group myRG --vmss myVMSS --instance-id myInstanceID1
$ kubectl aks config set-node node2 --id "/subscriptions/mySubID/resourceGroups/myRG/providers/Microsoft.Compute/virtualMachineScaleSets/myVMSS/virtualmachines/myInstanceID2"
$ kubectl aks show
nodes:
    node1:
        instance-id: myInstanceID1
        node-resource-group: myRG
        subscription: mySubID
        vmss: myVMSS
    node2:
        instance-id: myInstanceID2
        node-resource-group: myRG
        subscription: mySubID
        vmss: myVMSS

$ kubectl aks config use-node node1
$ kubectl aks check-apiserver-connectivity

$ kubectl aks config use-node node2
$ kubectl aks check-apiserver-connectivity

There is also an option to unset node information from the configuration using the unset-node/unset-all/unset-current-node commands.

Importing configuration

kubectl-aks can also import the node information from the Kubernetes API server or Azure API using the config import command. By default, if no flags are passed, kubectl-aks will try to retrieve the node information from the Kubernetes API server:

We can also import the node information using the AKS cluster credentials already available in the `kubeconfig` file:

```bash
# Create a cluster
$ az aks create ...
$ az aks get-credentials ...
$ kubectl get nodes
NAME                                STATUS   ROLES   AGE   VERSION
aks-agentpool-12345678-vmss000000   Ready    agent   4m    v1.23.15
aks-agentpool-12345678-vmss000001   Ready    agent   4m    v1.23.15
aks-agentpool-12345678-vmss000002   Ready    agent   4m    v1.23.15
# Import nodes into kubectl-aks
$ kubectl aks config import
$ kubectl aks config show
nodes:
    aks-agentpool-12345678-vmss000000:
        instance-id: "0"
        subscription: mySubID
        node-resource-group: myNRG
        vmss: myVMSS
    aks-agentpool-12345678-vmss000001:
        instance-id: "1"
        [...]
    aks-agentpool-12345678-vmss000002:
        instance-id: "2"
        [...]
# Start using one of those nodes
$ kubectl aks use-node aks-agentpool-12345678-vmss000000

If the Kubernetes API server is not available or we can't rely on it for some reason (e.g. we are investigating connectivity issues between nodes and the API server), we can use the --subscription, --resource-group and --cluster-name flags to retrieve the node information from the Azure API:

kubectl aks config import --subscription mySubID --resource-group myRG --cluster-name myCluster
kubectl aks config show

Precedence of configuration

Apart from the configuration file, we can also use the flags and environment variables to pass the node information to the commands. The precedence of the configuration is the following:

  1. Flags
  2. Environment variables
  3. Configuration file

Using the flags:

kubectl aks check-apiserver-connectivity --node aks-agentpool-77471288-vmss000013

or using the environment variables:

  • KUBECTL_AKS_NODE
  • KUBECTL_AKS_RESOURCE_ID
  • KUBECTL_AKS_SUBSCRIPTION, KUBECTL_AKS_NODE_RESOURCE_GROUP, KUBECTL_AKS_VMSS and KUBECTL_AKS_INSTANCE_ID
KUBECTL_AKS_NODE=aks-agentpool-77471288-vmss000013 kubectl aks check-apiserver-connectivity