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Update clusters

After you create a cluster with bmctl, you can change some aspects of the cluster's configuration by performing the following sequence of actions:

Change the values of certain fields in the cluster's configuration file, which by default is located here: bmctl-workspace/CLUSTER-NAME/CLUSTER-NAME.yaml.
Update the cluster by running the bmctl update command.

In this way, you can, for example, add or remove nodes in a cluster or replace nodes in a cluster. This document describes how to perform these and other updates to a cluster.

It's important to note, however, that many aspects of your cluster configuration are immutable and can't be updated after you create your cluster. For a comprehensive list of mutable and immutable fields, see the Cluster configuration field reference. The field reference is a sortable table. Click the column headings to change the sort order. Click a field name to view its description.

Add or remove nodes in a cluster

A node pool is a group of nodes within a cluster that have the same configuration. Keep in mind that a node always belongs to a node pool. To add a new node to a cluster, you need to add it to a particular node pool. Removing a node from a node pool amounts to removing the node from the cluster altogether.

There are three kinds of node pools in GKE on Bare Metal: control plane, load balancer, and worker node pools.

You add or remove a node from a node pool by adding or removing the node's IP address from a certain section of the cluster's configuration file. The following list shows which section of a manifest you need to edit for a given node pool:

Worker node pool: add/remove the node's IP address from the spec.nodes field that appears in the kind: NodePool section.
Control plane node pool: add/remove the node's IP address from the spec.controlPlane.nodePoolSpec.nodes field that appears in the kind: Cluster section.
Load balance node pool: You can't modify (add or remove IP addresses) from an existing load balancer address pool, nor can you remove an existing load balancer address pool. Once you've created a cluster, you can only add new address pools.

Example: how to remove a worker node

Here's a sample cluster configuration file that shows the specifications of two worker nodes:

---
apiVersion: baremetal.cluster.gke.io/v1
kind: NodePool
metadata:
  name: nodepool1
  namespace: cluster-cluster1
spec:
  clusterName: cluster1
  nodes:
  - address: 172.18.0.5
  - address: 172.18.0.6

You can remove a node from the worker node pool by performing the following steps:

Delete the node's IP address entry from the cluster configuration file:

---
apiVersion: baremetal.cluster.gke.io/v1
kind: NodePool
metadata:
  name: nodepool1
  namespace: cluster-cluster1
spec:
  clusterName: cluster1
  nodes:
  - address: 172.18.0.5

Update the cluster:
```
bmctl update cluster -c CLUSTER_NAME \
    --kubeconfig=KUBECONFIG
```
Make the following changes:
- Replace CLUSTER_NAME with the name of the cluster you want to update.
- If the cluster is a self-managing cluster (such as admin or standalone cluster), replace KUBECONFIG with the path to the cluster's kubeconfig file. If the cluster is a user cluster, replace KUBECONFIG with the path to the admin cluster's kubeconfig file.

It's important to note that bmctl has to drain Pods from a node before the node can be removed. Nodes aren't removed from the cluster if Pods can't be rescheduled to other nodes.

After the bmctl update command has executed successfully, it takes some time to complete the machine-preflight and machine-init jobs. You can view the status of nodes and their respective node pools by running the commands described in the Verify your updates section of this document.

Forcing the removal of a node

If the bmctl update command is unable to remove a node, you may have to force its removal from the cluster. For details, see Force-removing broken nodes.

Replace HA control plane nodes

You can replace high availability (HA) control plane nodes in admin, user, standalone, and hybrid clusters.

You replace a node in a cluster by performing the following steps:

Remove the node's IP address from the cluster configuration file.
Update the cluster.
Check the status of nodes in the cluster.
Add a new node's IP address to the same cluster configuration file.
Update the cluster.

The rest of this section goes through an example.

Here's a sample cluster configuration file that shows three control plane nodes in a user cluster:

---
apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
 name: user-cluster
 namespace: cluster-user-cluster
spec:
  controlPlane:
   nodePoolSpec:
     nodes:
     - address: 10.200.0.11
     - address: 10.200.0.12
     - address: 10.200.0.13

To replace the last node listed in the spec.controlPlane.nodePoolSpec.nodes section, perform the following steps:

Remove the node by deleting its IP address entry in the cluster configuration file. After making this change, the cluster configuration file should look something like this:

---
apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
 name: user-cluster
 namespace: cluster-user-cluster
spec:
  controlPlane:
   nodePoolSpec:
     nodes:
     - address: 10.200.0.11
     - address: 10.200.0.12

Update the cluster by running the following command:
```
bmctl update cluster -c CLUSTER_NAME \
    --kubeconfig=KUBECONFIG
```
Make the following changes:
- Replace CLUSTER_NAME with the name of the cluster you want to update.
- If the cluster is a self-managing cluster (such as admin or standalone cluster), replace KUBECONFIG with the path to the cluster's kubeconfig file. If the cluster is a user cluster, as it is in this example, replace KUBECONFIG with the path to the admin cluster's kubeconfig file.
After the bmctl update command has executed successfully, it takes some time to complete the machine-preflight and machine-init jobs. You can view the status of nodes and their respective node pools by running the commands described in the Verify your updates section of this document. Once the node pool and nodes are in a ready state, you can proceed to the next step.
Add a new control plane node to the node pool by adding the IP address of the new control plane node to the spec.controlPlane.nodePoolSpec.nodes section of the cluster configuration file. After making this change, the cluster configuration file should look something like this:
```
---
apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
 name: user-cluster
 namespace: cluster-user-cluster
spec:
  controlPlane:
   nodePoolSpec:
     nodes:
     - address: 10.200.0.11
     - address: 10.200.0.12
     - address: 10.200.0.14
```
Update the cluster by running the following command:
```
bmctl update cluster -c CLUSTER_NAME \
    --kubeconfig=KUBECONFIG
```
Make the following changes:
- Replace CLUSTER_NAME with the name of the cluster you want to update.
- If the cluster is a self-managing cluster (such as admin or standalone cluster), replace KUBECONFIG with the path to the cluster's kubeconfig file. If the cluster is a user cluster, as it is in this example, replace KUBECONFIG with the path to the admin cluster's kubeconfig file.

Verify your updates

You can view the status of nodes and their respective node pools with the kubectl get command.

For example, the following command shows the status of the node pools in the cluster namespace cluster-my-cluster:

kubectl -n cluster-my-cluster get nodepools.baremetal.cluster.gke.io

The system returns results similar to the following:

NAME                    READY   RECONCILING   STALLED   UNDERMAINTENANCE   UNKNOWN
cluster-my-cluster      3       0             0         0                  0
cluster-my-cluster-lb   2       0             0         0                  0
np1                     3       0             0         0                  0

Reconciling=1 means that the reconciliation step is still in progress. You should wait until the status changes to Reconciling=0.

You can also check status of nodes in the a cluster by running following command:

kubectl get nodes --kubeconfig=KUBECONFIG

If you need more information about how to diagnose your clusters, see Create snapshots for diagnosing clusters.

Features you can change with an update

Besides adding, removing or replacing nodes, you can use the bmctl update command to modify certain mutable field values, Custom Resources (CRs), and annotations in the cluster configuration file.

To update a cluster resource, edit the cluster configuration file and use bmctl update to apply your changes.

The following sections outline some common examples for updating an existing cluster by changing either a field value, CR or annotation.

`loadBalancer.addressPools`

The addressPools section contains fields for specifying load-balancing pools for bundled load balancers. You can add more load-balancing address pools at any time, but you can't remove or modify any existing address pools.

addressPools:
- name: pool1
  addresses:
  - 192.168.1.0-192.168.1.4
  - 192.168.1.240/28
- name: pool2
  addresses:
  - 192.168.1.224/28

Prevent inadvertent cluster deletion

If you add the baremetal.cluster.gke.io/prevent-deletion: "true" annotation to your cluster configuration file, you are prevented from deleting the cluster. For example, running kubectl delete cluster or bmctl reset cluster produce an error.

apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
  name: ci-10c3c6f4d9c698e
  namespace: cluster-ci-10c3c6f4d9c698e
  annotations:
    baremetal.cluster.gke.io/prevent-deletion: "true"
spec:
  clusterNetwork:

`bypassPreflightCheck`

The default value of the bypassPreflightCheck field is false. If you set this field to true in the cluster configuration file, the internal preflight checks are ignored you apply resources to existing clusters.

apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
  name: cluster1
  namespace: cluster-cluster1
  annotations:
    baremetal.cluster.gke.io/private-mode: "true"
spec:
  bypassPreflightCheck: true

`loginUser`

You can set the loginUser field under the node access configuration. This field supports passwordless sudo capability for machine login.

apiVersion: baremetal.cluster.gke.io/v1
kind: Cluster
metadata:
  name: cluster1
  namespace: cluster-cluster1
  annotations:
    baremetal.cluster.gke.io/private-mode: "true"
spec:
  nodeAccess:
    loginUser: abm

`NetworkGatewayGroup`

The NetworkGatewayGroup custom resource is used to provide floating IP addresses for advanced networking features, such as the egress NAT gateway or the bundled load-balancing feature with BGP. To use the NetworkGatewayGroup custom resource and related networking features, you must set clusterNetwork.advancedNetworking to true when you create your clusters.

apiVersion: networking.gke.io/v1
kind: NetworkGatewayGroup
  name: default
  namespace: cluster-bm
spec:
  floatingIPs:
  - 10.0.1.100
  - 10.0.2.100

`BGPLoadBalancer`

When you configure bundled load balancers with BGP, the data plane load balancing uses, by default, the same external peers that were specified for control plane peering. Alternatively, you can configure the data plane load balancing separately, using the BGPLoadBalancer custom resource (and the BGPPeer custom resource). For more information, see Configure bundled load balancers with BGP.

apiVersion: networking.gke.io/v1
kind: BGPLoadBalancer
metadata:
  name: default
  namespace: cluster-bm
spec:
  peerSelector:
    cluster.baremetal.gke.io/default-peer: "true"

`BGPPeer`

When you configure bundled load balancers with BGP, the data plane load balancing uses, by default, the same external peers that were specified for control plane peering. Alternatively, you can configure the data plane load balancing separately, using the BGPPeer custom resource (and the BGPLoadBalancer custom resource). For more information, see Configure bundled load balancers with BGP.

apiVersion: networking.gke.io/v1
kind: BGPPeer
metadata:
  name: bgppeer1
  namespace: cluster-bm
  labels:
    cluster.baremetal.gke.io/default-peer: "true"
spec:
  localASN: 65001
  peerASN: 65002
  peerIP: 10.0.3.254
  sessions: 2

`NetworkAttachmentDefinition`

You can use the bmctl update command to modify NetworkAttachmentDefinition custom resources that correspond to the network.

apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
  name: gke-network-1
  namespace: cluster-my-cluster
spec:
  config: '{
  "type": "ipvlan",
  "master": "enp2342",
  "mode": "l2",
  "ipam": {
    "type": "whereabouts",
    "range": "172.120.0.0/24"

After you modify the config file, update the cluster by running the following bmctl update command:

bmctl update cluster -c CLUSTER_NAME --kubeconfig=KUBECONFIG

Make the following changes:

Replace CLUSTER_NAME with the name of the cluster you want to update.
If the cluster is a self-managing cluster (such as admin or standalone cluster), replace KUBECONFIG with the path to the cluster's kubeconfig file. If the cluster is a user cluster, replace KUBECONFIG with the path to the admin cluster's kubeconfig file.