docker statsの結果を整形

check_stats.rb

require 'bigdecimal'

# while true; do TZ="Asia/Tokyo" ruby check_stats.rb; sleep 3; done > stat_log.txt

cmd = <<EOS
sudo docker stats --no-stream --format '{{.Name}}\t{{.ID | printf "%.10s" }}\t{{.CPUPerc}}\t{{.MemUsage}}'
EOS

def to_mib(str)
  val = BigDecimal.new(str[0..-3])
  if str.end_with?('GiB')
    val * 1000
  else
    val
  end
end

def memory_info(str)
  current, max = str.split(/\//).map(&:strip)
  [to_mib(current).to_f, to_mib(max).to_f]
end

now = Time.now.strftime('%Y-%m-%d %H:%M:%S')
`#{cmd}`.lines.map(&:chomp).each do |line|
  name, id, cpu, mem = line.split(/\t/)
  cpu = cpu[0..-1].to_f
  mem_use, mem_total = memory_info(mem)

  puts [now, name, id, cpu, mem_use, mem_total].join("\t")
end