CloudWatchのAPI叩いてメトリクスを手に入れる

こんな感じで取得できます。

与える値と返ってくる値の中で、手に入れたい値(例えば対象のメトリクスの最新の数値)
を取り出すまでに苦労しました。

get_cloudwatch_rds.rb

#!/usr/bin/env ruby

require 'aws-sdk'

ACCESS_KEY_ID     = "YOUR_AWS_KEY_ID"
SECRET_ACCESS_KEY = "YOUR_AWS_SECRET_KEY"
ENDPOINT          = "YOURENDPOINT"

cw = AWS::CloudWatch.new(
  :access_key_id        => ACCESS_KEY_ID,
  :secret_access_key    => SECRET_ACCESS_KEY,
  :cloud_watch_endpoint => ENDPOINT
).client

statistics = cw.get_metric_statistics({
  :namespace   => 'AWS/RDS',
  :metric_name => 'CPUUtilization',
  # default RDS metric
  # CPUUtilization, FreeStorageSpace, DiskQueueDepth, FreeableMemory, SwapUsage, ReadIOPS, ReadLatency, ReadThroughput, WriteIOPS, WriteLatency, WriteThroughput
  dimensions_name DBInstanceIdentifier
  :statistics  => ['Average'],
  :dimensions  => [
    { :name => "DBInstanceIdentifier", :value => "RDSNAME" },
  ],
  :start_time  => (Time.now - 120).iso8601,
  :end_time    => Time.now.iso8601,
  :period      => 60
})
# p statistics[:datapoints][0][:average]
p statistics

get_cloudwatch_ec2.rb

#!/usr/bin/env ruby

require 'aws-sdk'

ACCESS_KEY_ID     = "YOUR_AWS_KEY_ID"
SECRET_ACCESS_KEY = "YOUR_AWS_SECRET_KEY"
ENDPOINT          = "YOURENDPOINT"

cw = AWS::CloudWatch.new(
  :access_key_id        => ACCESS_KEY_ID,
  :secret_access_key    => SECRET_ACCESS_KEY,
  :cloud_watch_endpoint => ENDPOINT
).client

statistics = cw.get_metric_statistics({
  :namespace   => 'AWS/EC2',
  :metric_name => 'CPUUtilization',
  # default EC2 metric
  # CPUUtilization, FreeStorageSpace, DiskQueueDepth, FreeableMemory, SwapUsage, ReadIOPS, ReadLatency, ReadThroughput, WriteIOPS, WriteLatency, WriteThroughput
  :statistics  => ['Average'],
  :dimensions  => [
    { :name => "InstanceId", :value => "YOURINSTANCEID" },
  ],
  :start_time  => (Time.now - 120).iso8601,
  :end_time    => Time.now.iso8601,
  :period      => 60
})
p statistics[:datapoints][0][:average]
# p statistics