Lightsnap

Running Lightsail instances and don't like the auto snapshot AWS provides? Run this python module on Lambda to schedule snapshot creation with more flexibility. By using schedule expression and the module's very own config, you can automate snapshot creation however you like.

INSTALL

Copy the sample config into src, edit it to your liking.

cp doc/config.jsonc src/config.jsonc

The following set up will keep max of 3 snapshots for the instance named "Ubuntu-1".

{
	"boto": { // For local use. On Lambda, "the role will be assumed"
		// "region_name": "",
		// "profile_name": ""
	},
	"snapshot-instance": [
		{
			"instance-name": "Ubuntu-1",
			"prefix": "LIGHTSNAP_Ubuntu-1_", // snapshot name prefix
			"nb-copy": 3
		}
	]
}

IAM Role

Create an IAM role for the Lambda function. Permissions requires in addition to the basic execution permissions.

• GetInstanceSnapshots
• GetInstanceSnapshot
• DeleteInstanceSnapshot
• CreateInstanceSnapshot

Tip: the ARN of a Lightsail instance is made up of a randomly generated UUID that's not exposed on the web management console. In order to get the ARN of an instance for CreateInstanceSnapshot action, you need to use awscli like so.

aws lightsail get-instances

Build and Upload

Run make to generate the layer and the function code bundle. Upload lambda_layer.zip to create the layer for the function and create the Lambda function using lambda_function.zip using following params:

• Runtime: Python 3.12
• Arch: arm64
• Timeout: 5 minutes or more recommended! (AWS APIs are SLOW)

Trigger Rule

Create a rule on EventBridge to trigger the Lambda function. The following cron example will run the function at 16:30 UTC every other day.

30 16 */2 * ? *

So in this example, if nb-copy is set to 3, snapshots spanning 6 days period will be maintained.

DONE!

Now forget that you've ever done this and move on with your life!

Words on SNS Topic and Service Interruption

If you wish, create an SNS topic to receive notification in the event of unsuccessful run. Errors will never occur as long as the service in your region runs smoothly. But you may want to fire the function manually after a service interruption. To manually run the function, use the test tab in the web management console.

WARNING! Make sure you use one key-value pair otherwise the function will run more than once, leaving you with 2 lost snapshots.