Google Cloud Compute Create Snapshot with Rotate

gistfile1.rb

#!/bin/ruby
require 'json'
require 'time'
require 'syslog'


class Snapshot

  def initialize()
    @format = 'json'
    @zone = get_zone
    @hostname = hostname
    @time = Time.now.to_i
    @regex = ".*#{@hostname}.*"
    @snapshot_name = "#{@hostname}-#{@time}"
    @rotate_days = 3
    @rotate_period = @rotate_days * 60 * 60 *24
    @disk_name = get_primary_disk
  end

  def get_zone
    output = `curl --silent "http://metadata.google.internal/computeMetadata/v1/instance/zone" -H "Metadata-Flavor: Google"`
    output.split("/").last
  end

  def hostname
    hostname = `curl --silent "http://metadata.google.internal/computeMetadata/v1/instance/hostname" -H "Metadata-Flavor: Google"`
    hostname.split(".").first
  end

  def get_primary_disk
    instance = `gcloud compute instances describe #{@hostname} --format json --zone #{@zone}`
    instance = JSON.parse instance
    instance["disks"][0]["deviceName"]
  end

  def run_backup
    create_snapshot
    delete_old_snapshots
    msg = "Finished the snapshots"
    Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS) { |s| s.info msg }
  end

  def create_snapshot
    msg = "Creating snapshot #{@snapshot_name}"
    Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS) { |s| s.info msg }
    `gcloud compute disks snapshot #{@disk_name} --snapshot-name #{@snapshot_name} --zone #{@zone}`
  end

  def delete_old_snapshots
    snapshots = get_snapshots
    if snapshots.length > 0
      snapshots.each do |name|
        msg = "Deleting snapshot #{name}"
        Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS) { |s| s.info msg }
        `gcloud compute snapshots delete #{name} --quiet`
      end
    else
      msg = "No snapshots to delete"
      Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS) { |s| s.info msg }
    end
  end

  def get_snapshots
    msg = "Finding snapshots older than #{Time.now - @rotate_period}"
    Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS) { |s| s.info msg }
    instances = `gcloud compute snapshots list --format #{@format} --regex #{@regex}`
    instances = JSON.parse instances
    instances.select { |instance| Time.parse(instance["creationTimestamp"]) <= Time.now - (@rotate_period) }.map { |instance| instance["name"] }
  end
end


snapshot = Snapshot.new
snapshot.run_backup

Requires service account on the instance running this

Now logs to syslog and gets the disk name from gcloud.