S3 buckets size

cloudwatch_s3.rb

require  'aws-sdk-cloudwatch'
require 'aws-sdk-s3'

START_DATE = Time.new(2018,1,21).utc
END_DATE = Time.new(2018,1,22).utc
REGION = "eu-west-1"

CW = Aws::CloudWatch::Client.new(region: REGION)
S3 = Aws::S3::Resource.new(region: REGION)

def bytes_to_s(s)
    return "0 bytes" if s.nil?
    suffix = "bytes"
    if s >= 1024
        s = (s/1024).to_f
        suffix = "kb"
    end
    if s >= 1024
        s = (s/1024).to_f
        suffix = "MB"
    end
    if s >= 1024
        s = (s/1024).to_f
        suffix = "GB"
    end
    if s >= 1024
        s = (s/1024).to_f
        suffix = "TB"
    end
    "#{s.round(2)} #{suffix}"
end

def get_size(bucket)
    a = CW.get_metric_statistics({namespace: "AWS/S3", metric_name:"BucketSizeBytes", dimensions: [{name:'StorageType', value:'StandardStorage'}, 
    {name:"BucketName", value:bucket}],
    start_time: START_DATE, end_time: END_DATE, 
    period:86400, statistics:["Maximum"], unit: "Bytes"}).datapoints.first

    return 0 if a.nil?
    a.maximum
end

buckets = S3.buckets.map{|b| b.name}
puts "buckets #: #{buckets.count}"


tot = buckets.reduce({}){|acc, b| acc[b] = get_size(b); acc}
tot.sort_by{|_, v| -v}.each do |k, v|
    puts "#{k}: #{bytes_to_s(v)}"
end