put CloudWatchLogs with X_CLOUDWATCH_LOG header

x_cloudwatchlog_filter.rb

=begin
require 'grape'
require 'uuid'
require 'ltsv'

class Hello < Grape::API
  post 'teapot' do
    status 201
    id = UUID.generate
    header XCloudwatchLogFilter::X_CLOUDWATCH_LOG, LTSV.dump({user_id:id, resource:'/teapot'})
    body = request.body.read
    {id:id}
  end
end

use XCloudwatchLogFilter
run Hello
=end


require 'aws-sdk'

class XCloudwatchLogFilter
  LOG_GROUP_NAME = 'example'
  LOG_STREAM_NAME = 'api_calls'
  X_CLOUDWATCH_LOG = 'x_cloudwatch_log'

  @@client = nil
  @@next_sequence_token = nil
  def self.put_log_event(message)
    @@client ||= Aws::CloudWatchLogs::Client.new(region:ENV['AWS_REGION'], http_proxy:ENV['HTTPS_PROXY']||ENV['HTTP_PROXY'])
    param = {
      log_group_name:LOG_GROUP_NAME,
      log_stream_name:LOG_STREAM_NAME,
      log_events:[{
        timestamp:(Time.now.to_f*1000).to_i,
        message:message
      }]
    }
    param.merge!(sequence_token:@@next_sequence_token) if @@next_sequence_token
    begin
      res = @@client.put_log_events(param)
    rescue Aws::CloudWatchLogs::Errors::InvalidSequenceTokenException=>e
      seq = e.to_s.scan(/\d{48,}/)[0]
      param.merge!(sequence_token:seq)
      retry
    end
    p(log:res)
    @@next_sequence_token = res.next_sequence_token
  end

  def initialize(app)
    @app = app
  end

  def call(env)
    res = @app.call(env)
    apicall = res[1][X_CLOUDWATCH_LOG]
    if apicall
      XCloudwatchLogFilter.put_log_event(apicall)
      res[1].delete(X_CLOUDWATCH_LOG)
    end
    res
  end
end