ebs-snapshot-lambda

AWS lambda function to snapshot EBS volumes and purge old snapshots.

Requirements

The EBS volumes that are to be snapshotted need to be tagged with two keys:

Snapshot (required) - the presence of this key indicates that this EBS volume needs to be snapshotted when the lambda function runs. Ideally, the lambda function will be scheduled once a day.
Retention (optional) - the value of this tag specifies the number of days the snapshot has to be retained before it is purged. Any snapshot that is created is tagged with the date at which it should be deleted, based on this value. If this tag is not present, a defaultRetention value specified in lambda/config.json is used (default: 7 days).

Configuration

The lambda/config.json has the following configurations that can be modified as required:

defaultRetention - A volume that is marked to be snapshotted with the Snapshot tag can also have a Retention tag with the number of days its snapshots have to be retained before purge. If the Retention tag is not present, this value will be used.
copyVolumeTagsToSnapshot - If this is set to true, all the tags of the volume, except Snapshot and Retention, are copied over to the snapshot.

Installation

Manual

Once lambda/config.json has been edited as required, run npm install --production or yarn install --production from lambda/ and zip up the folder. The zip archive can then be deployed like any other lambda function.

Terraform

The repo also comes with terraform plans to setup and install the lambda function, along with the required schedules and IAM role/policy. Verify with terraform plan and deploy with terraform apply.

Using as a module

The terraform plans can also be used as a module within your existing terraform project. Add as a module with something like below:

module "ebs-backup" {
  source = "github.com/manojlds/ebs-snapshot-lambda//terraform"

  lambda_prepared_source_dir = "${path.root}/ebs-backup-temp/source"
  lambda_archive_path = "${path.root}/ebs-backup-temp/dist/ebs_snapshot_lambda.zip"
}

Limitations

The lambda has following limitations / assumptions / compromises. Happy to hear suggestions or PRs addressing these:

Will not work for large number of volumes. AWS API limits and Lambda runtime limits are not take into account yet. I plan to add a "bulk" version that can handle 10s or 100s of volumes.
Assumes that snapshot is taken once a day. The unit is days and not hours. Will not work correctly for taking snapshots for, say, every 6 hours - will purge all the snapshots at once after the retention days.
The lambda will create snapshots twice if it is triggered twice irrespective of whether snasphot was already taken for the day.

License

This is an open source project licensed under the Apache License, Version 2.0.

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