如何在kops中为AWS单可用区配置单主节点？多AZ集群主节点配置问题

Hey there! I’ve helped lots of folks work through kops master node configuration issues, so let’s get yours sorted out. First, we’ll fix the extra master in us-east-1c, then cover how to deploy a single master in one AZ.

Looking at your instance group details, the master-us-east-1c group is stuck at 2 nodes—let’s adjust that to 1 to match your other AZs. Here’s how:

Step 1: Inspect the current instance group config #

First, pull the full configuration for the problematic group to confirm its settings:

kops get ig master-us-east-1c -o yaml

You’ll see fields like minSize, maxSize, and subnets—we only need to tweak the size values here.

Step 2: Edit the instance group configuration #

Export the config to a file so you can modify it easily:

kops get ig master-us-east-1c -o yaml > master-us-east-1c.yaml

Open the file in your editor, then update both minSize and maxSize from 2 to 1. Double-check that the subnets field still only lists us-east-1c (which it does in your current setup).

Step 3: Apply the changes to your cluster #

Replace the existing instance group with your edited config:

kops replace -f master-us-east-1c.yaml

Then push the update to your cluster:

kops update cluster --yes

Step 4: Roll out the change gracefully #

To ensure the cluster scales down without disruption, run a rolling update:

kops rolling-update cluster --yes

This will terminate the extra master node in us-east-1c and set the group to 1 node, matching your other AZs.

Why this works: #

Kops requires the total number of master nodes to be an odd number (to prevent split-brain scenarios in high-availability setups). Your desired setup (1 master per AZ, total 3 nodes) is an odd count, which is valid—this is why kops will allow the adjustment from 2 to 1.

If you want to create a new cluster with just one master in a single AZ (ideal for testing or non-production environments), follow these steps:

Create the cluster with single master and AZ #

Use the --zones flag to specify only one AZ, and --master-count 1 to set the master node count:

kops create cluster \
  --name your-cluster-name.example.com \
  --zones us-east-1a \
  --master-count 1 \
  --master-size m3.medium \
  --node-size m4.xlarge \
  --node-count 3

Verify the setup #

After creating the cluster, check the instance groups to confirm everything is configured correctly:

kops get ig

You’ll see a single master instance group with MIN and MAX set to 1, tied exclusively to your chosen AZ.

Important Note: #

A single master cluster lacks high availability—if that master node goes down, your cluster control plane will be unavailable. This setup is not recommended for production workloads.

内容的提问来源于stack exchange，提问作者Xiang Zhang