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Scaling Cluster Worker Nodes

In the process of software development and operation, business growth often requires adding worker nodes to a cluster to meet the demand. For clusters deployed using kubean, we can use a declarative approach to quickly scale the cluster's worker nodes.

In the kubean/example/scale directory cloned to your local machine, there is a sample template for scaling worker nodes:

The main configuration files and purposes in the scale file are as follows: 
    scale
    ├── 1.addWorkNode                             # Template for adding worker nodes
    │   ├── ClusterOperation.yml                       # kubean version and task configuration
    │   └── HostsConfCM.yml                            # configuration of current cluster node information
    └── 2.delWorkNode                             # Template for deleting worker nodes
    │   ├── ClusterOperation.yml                       # kubean version and task configuration
    │   └── HostsConfCM.yml                             # configuration of current cluster node information

By observing the scaling configuration template in the scale file, it can be seen that scaling the cluster's worker nodes only requires executing two configuration files: HostsConfCM.yml and ClusterOperation.yml. You will need to replace the parameters such as the information of the new node with your actual parameters.

Using the example of a single-node cluster deployed in all-in-one mode let's demonstrate how to scale the cluster's worker nodes.

Note: Before scaling the cluster, you must have completed the deployment of a set of cluster using kubean.

Scaling Worker Nodes

1. Add New Node Host Parameters to HostsConfCM.yml

To add a new node configuration to the ConfigMap named mini-hosts-conf in the existing all-in-one mode, we will add a new worker node node2 based on the original main node node1.

Specifically, we can go to the path kubean/examples/scale/1.addWorkNode/, edit the prepared node configuration ConfigMap template HostsConfCM.yml, and replace the following parameters with your actual parameters:

  • <IP2>: the IP address of the node.
  • <USERNAME>: the username to log in to the node. We recommend using either "root" or a user with root privileges.
  • <PASSWORD>: the password to log in to the node.

The template content of HostsConfCM.yml in the kubean/examples/scale/1.addWorkNode/ path is as follows:

HostsConfCM.yml 模板 
apiVersion: v1
kind: ConfigMap
metadata:
  name: mini-hosts-conf
  namespace: kubean-system
data:
  hosts.yml: |
    all:
      hosts:
        node1:
          ip: <IP1>
          access_ip: <IP1>
          ansible_host: <IP1>
          ansible_connection: ssh
          ansible_user: <USERNAME>
          ansible_password: <PASSWORD>
        node2:
          ip: <IP2>
          access_ip: <IP2>
          ansible_host: <IP2>
          ansible_connection: ssh
          ansible_user: <USERNAME>
          ansible_password: <PASSWORD>
      children:
        kube_control_plane:
          hosts:
            node1:
        kube_node:
          hosts:
            node1:
            node2:
        etcd:
          hosts:
            node1:
        k8s_cluster:
          children:
            kube_control_plane:
            kube_node:
        calico_rr:
          hosts: {}

Important Parameters:

  • all.hosts.node1: The original main node that already exists in the cluster.
  • all.hosts.node2: The worker node to be added to the cluster.
  • all.children.kube_node.hosts: The group of worker nodes in the cluster.

Example

apiVersion: v1
kind: ConfigMap
metadata:
  name: mini-hosts-conf
  namespace: kubean-system
data:
  hosts.yml: |
    all:
      hosts:
        node1:
          ip: 10.6.175.10 # Your node's IP
          access_ip: 10.6.175.10 # Your node's IP
          ansible_host: 10.6.175.10 # Your node's IP
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node
          ansible_password: password01 # The password to log in to the node
      children:
        kube_control_plane:
          hosts:
            node1:
        kube_node:
          hosts:
            node1:
        etcd:
          hosts:
            node1:
        k8s_cluster:
          children:
            kube_control_plane:
            kube_node:
        calico_rr:
          hosts: {}

apiVersion: v1
kind: ConfigMap
metadata:
  name: mini-hosts-conf
  namespace: kubean-system
data:
  hosts.yml: |
    all:
      hosts:
        node1:
          ip: 10.6.175.10 # Your node's IP
          access_ip: 10.6.175.10 # Your node's IP
          ansible_host: 10.6.175.10 # Your node's IP
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node
          ansible_password: password01 # The password to log in to the node
        node2:
          ip: 10.6.175.20 # Your node's IP
          access_ip: 10.6.175.20 # Your node's IP
          ansible_host: 10.6.175.20 # Your node's IP
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node
          ansible_password: password01 # The password to log in to the node
      children:
        kube_control_plane:
          hosts:
            node1:
        kube_node:
          hosts:
            node1:
            node2:
        etcd:
          hosts:
            node1:
        k8s_cluster:
          children:
            kube_control_plane:
            kube_node:
        calico_rr:
          hosts: {}

2. Add Scaling Task through ClusterOperation.yml

Go to the path kubean/examples/scale/1.addWorkNode/ and edit the template ClusterOperation.yml,replacing the following parameter with your actual parameter:

The template content of ClusterOperation.yml in the kubean/examples/scale/1.addWorkNode/ path is as follows:

apiVersion: kubean.io/v1alpha1
kind: ClusterOperation
metadata:
  name: cluster-mini-awn-ops
spec:
  cluster: cluster-mini
  image: ghcr.m.daocloud.io/kubean-io/spray-job:<TAG> # Please replace <TAG> with the specified version, such as v0.4.9
  actionType: playbook
  action: scale.yml
  extraArgs: --limit=node2
Important Parameters:

  • spec.cluster: specifies the name of the cluster to be scaled. The above example specifies the cluster named cluster-mini as the scaling target.
  • spec.action:: specifies the kubespray script for scaling the node, which is set to scale.yml here.
  • spec.extraArgs: specifies the limit of the nodes to be scaled. Here, the --limit= parameter is used to limit the scaling to the node2.

For example, the following is an example of ClusterOperation.yml:

ClusterOperation.yml Example 
---
apiVersion: kubean.io/v1alpha1
kind: ClusterOperation
metadata:
  name: cluster-mini-awn-ops
spec:
  cluster: cluster-mini
  image: ghcr.m.daocloud.io/kubean-io/spray-job:v0.5.2
  actionType: playbook
  action: scale.yml
  extraArgs: --limit=node2

3.Apply all configurations under scale/1.addWorkNode folder

After completing the above steps and saving the HostsConfCM.yml and ClusterOperation.yml files, run the following command:

$ kubectl apply -f examples/install/scale/1.addWorkNode/

At this point, you have completed the scaling of a working node in a cluster.

Shrink Working Nodes

1. Add Scaling Task through ClusterOperation.yml

Go to the path kubean/examples/scale/2.delWorkNode/ and edit the template ClusterOperation.yml, replacing the following parameter with your actual parameter:

The template content of ClusterOperation.yml in the kubean/examples/scale/2.delWoorkNode/ path is as follows:

apiVersion: kubean.io/v1alpha1
kind: ClusterOperation
metadata:
  name: cluster-mini-dwn-ops
spec:
  cluster: cluster-mini
  image: ghcr.m.daocloud.io/kubean-io/spray-job:<TAG> # Please replace <TAG> with the specified version, such as v0.4.9
  actionType: playbook
  action: remove-node.yml
  extraArgs: -e node=node2
重要参数：

  • spec.cluster: specifies the name of the cluster to be scaled. The above example specifies the cluster named cluster-mini as the scaling target.
  • spec.action: specifies the kubespray script for scaling the node, which is set to remove-node.yml here.
  • spec.extraArgs: specifies the nodes to be scaled down. Here, the -e parameter is used to specify the node2 to be scaled down.

For example, the following is an example of ClusterOperation.yml:

ClusterOperation.yml Example 
apiVersion: kubean.io/v1alpha1
kind: ClusterOperation
metadata:
  name: cluster-mini-dwn-ops
spec:
  cluster: cluster-mini
  image: ghcr.m.daocloud.io/kubean-io/spray-job:v0.5.2
  actionType: playbook
  action: remove-node.yml
  extraArgs: -e node=node2

2.Apply the ClusterOperation scaling task list under the scale/2.delWorkNode directory

After completing the above steps and saving the ClusterOperation.yml file, run the following command:

$ kubectl apply -f examples/install/scale/2.delWorkNode/ClusterOperation.yml

By default, enter the kubean-system namespace and check the execution status of the scaling task: 

$ kubectl -n kubean-system get pod | grep cluster-mini-dwn-ops
To learn about the progress of the scaling task, you can view the logs of the pod.

3. Delete the working node host parameters through HostsConfCM.yml

We have executed the scaling task through the above two steps. After the scaling task is completed, node2 will be permanently removed from the existing cluster. Then, we need to complete the final step, which is to remove the node2 information from the node configuration related Configmap.

Go to the path kubean/examples/scale/2.delWorkNode/ and edit the prepared node configuration template HostsConfCM.yml to remove the configuration of the working node that needs to be removed.

The deleted parameters are as follows:

  • all.hosts: The node2 node access parameters.
  • all.children.kube_node.hosts: The node name node2.

Example

apiVersion: v1
kind: ConfigMap
metadata:
  name: mini-hosts-conf
  namespace: kubean-system
data:
  hosts.yml: |
    all:
      hosts:
        node1:
          ip: 10.6.175.10 # Your node's IP
          access_ip: 10.6.175.10 # Your node's IP
          ansible_host: 10.6.175.10 # Your node's IP
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node
          ansible_password: password01 # The password to log in to the node
        node2:
          ip: 10.6.175.20 # The IP address of node 2 is added
          access_ip: 10.6.175.20 # The IP address of node 2 is added
          ansible_host: 10.6.175.20 # The IP address of node 2 is added
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node2
          ansible_password: password01 # password to log in to the node2
      children:
        kube_control_plane:
          hosts:
            node1:
        kube_node:
          hosts:
            node1:
            node2:
        etcd:
          hosts:
            node1:
        k8s_cluster:
          children:
            kube_control_plane:
            kube_node:
        calico_rr:
          hosts: {}

apiVersion: v1
kind: ConfigMap
metadata:
  name: mini-hosts-conf
  namespace: kubean-system
data:
  hosts.yml: |
    all:
      hosts:
        node1:
          ip: 10.6.175.10 # Your node's IP
          access_ip: 10.6.175.10 # Your node's IP
          ansible_host: 10.6.175.10 # Your node's IP
          ansible_connection: ssh
          ansible_user: root # The username to log in to the node
          ansible_password: password01 # The password to log in to the node
      children:
        kube_control_plane:
          hosts:
            node1:
        kube_node:
          hosts:
            node1:
        etcd:
          hosts:
            node1:
        k8s_cluster:
          children:
            kube_control_plane:
            kube_node:
        calico_rr:
          hosts: {}

After completing the above steps and saving the HostsConfCM.yml file, execute the following command:

$ kubectl apply -f examples/install/scale/2.delWorkNode/HostsConfCM.yml

At this point, we have removed the node2 worker node from the cluster and cleaned up all the host information related to node2. The entire scaling down operation is now complete.