使用Terraform搭建VPS集群后，如何实现垂直扩容？

Hey there! Glad to hear your Terraform-managed VPS cluster is running smoothly. Let's break down how to perform vertical scaling (upgrading the instance size) for your 3 DigitalOcean Droplets.

Step 1: Update the Instance Size Configuration #

You've defined the swarm_instance_size variable to control your Droplet size, so we'll start here. You have two flexible options to adjust this:

Option 1: Modify the Variable's Default Value

Edit your Terraform variable definition to set the new desired size (e.g., 2gb, 4gb, or any valid DigitalOcean instance size):

variable "swarm_instance_size" {
  default = "2gb" # Replace with your target instance size
}

Option 2: Pass the New Size via Command Line (No Code Change)

If you prefer not to modify your code (for example, a one-off scaling test), use the -var flag when running terraform apply:

terraform apply -var "swarm_instance_size=2gb"

Step 2: Preview the Change (Always Do This First!) #

Before making any live changes, run terraform plan to verify exactly what Terraform will do:

terraform plan

You should see output indicating that all 3 digitalocean_droplet.server resources will be updated in-place. This is critical—it means Terraform will resize your existing Droplets instead of destroying and recreating them, so your data and setup stay intact.

Important: While DigitalOcean's resize operation is generally safe, it's smart to take snapshots of your Droplets before scaling, just as a precaution.

Step 3: Execute the Scaling #

Once you're comfortable with the plan, run the apply command to trigger the resize:

terraform apply

Confirm the change when prompted, and Terraform will handle resizing all 3 Droplets to the new size. Keep in mind your Droplets may restart during this process, so schedule this during a maintenance window if your application can't tolerate brief downtime.

Key Notes to Keep in Mind #

• Region Availability: Ensure your target instance size is available in the sfc1 region you're using. Some sizes are region-specific, so double-check compatibility first.
• Billing: Resizing will adjust your billing rate to match the new instance size—review DigitalOcean's pricing for your target size beforehand.
• Partial Scaling: If you only want to resize a subset of Droplets, you'll need to split your resource definition. For example, create a separate digitalocean_droplet block using for_each instead of count to specify individual sizes for different instances.

内容的提问来源于stack exchange，提问作者Snowball