postgres_snapshot.rb

#!/usr/bin/env ruby
require 'date'
require 'pg'

# 設定
TARGET = 'zroot/postgres' # 対象パーティション
DAYS = 7 # 保管する日数
DSN = 'postgres://postgres@localhost/mastodon' # PG形式の接続文字列

def snapshots(target = TARGET)
  return `zfs list -t snapshot`
    .each_line
    .map {|line| line.split(/\s+/).first}
    .select {|v| v.split('@').first == target}
    .map do |name|
      date = Date.parse(name.match(/[0-9]{4}-[0-9]{2}-[0-9]{2}/)[0]) rescue nil
      {name:, date:}
    end
end

def clean(snapshots)
  snapshots.each do |snapshot|
    if snapshot[:date].nil? || snapshot[:date] < Date.today - DAYS
      system "zfs destroy #{snapshot[:name]}"
      puts "destroy snapshot: #{snapshot[:name]}"
    end
  end
end

def create_snapshot
  name = "#{TARGET}@#{Time.now.strftime('%F_%T')}"
  pg = PG::Connection.new(DSN)
  pg.exec_params(%{SELECT * FROM pg_backup_start($1, false)}, [name])
  system "zfs snapshot #{name}"
  puts "create snapshot: #{name}"
  pg.exec(%{SELECT * FROM pg_backup_stop(true)})
end

begin
  clean(snapshots)
  create_snapshot
rescue => e
  warn e.message
  exit 1
end