Add support for fast snapshot restore

[ziggythehamster]

Community Note

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Description

When images are taken and snapshots copied, Packer users should be able to enable EBS fast snapshot restore on those snapshots for some list of availability zones. Note that the list of AZs would be per snapshot, which could span regions, so the configuration syntax might get a little hairy.

Use Case(s)

Make instance launches not suffer from the degraded performance that comes with launching from an AMI or EBS snapshot while the volume is initializing.

Potential configuration

source "amazon-ebssurrogate" "foo" {
  ami_regions = ["us-east-1", "us-west-2"]

  ami_fast_snapshot_restore {
    region             = "us-east-1"
    availability_zones = ["us-east-1a", "us-east-1b"]
  }

  ami_fast_snapshot_restore {
    region             = "us-west-2"
    availability_zones = ["us-west-2a", "us-west-2b"]
  }
}

Potential References

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-fast-snapshot-restore.html