zsprackett/cloudwatchtographite

# _*_ coding: utf-8 _*_
# frozen_string_literal: true
# == Synopsis
# CloudwatchToGraphite retrieves metrics from the Amazon CloudWatch APIs
# and passes them on to a graphite server
#
# == Author
# S. Zachariah Sprackett <zac@sprackett.com>
#
# == License
# The MIT License (MIT)
#
# == Copyright
# Copyright (C) 2013 - S. Zachariah Sprackett <zac@sprackett.com>
#
require 'json'
require 'yaml'

module CloudwatchToGraphite
  # Load metrics from a file and parse them into a
  # CloudwatchToGraphite::MetricDefinition object
  #
  class LoadMetrics
    def self.from_json_file(filename)
      if !File.readable?(filename)
        warn 'Unable to read %s' % filename
        []
      else
        File.open(filename, 'r') do |f|
          begin
            contents = JSON.load(f)
            load_content(contents)
          rescue Exception
            warn 'Failed to parse %s' % filename
            []
          end
        end
      end
    end

    def self.from_yaml_file(filename)
      if !File.readable?(filename)
        warn 'Unable to read %s' % filename
        []
      else
        begin
          contents = YAML.load_file(filename)
          load_content(contents)
        rescue Exception
          warn 'Failed to parse %s' % filename
          []
        end
      end
    end

    private

    def self.load_content(contents, _strict = false)
      metrics = []
      Validator.hash_with_key_of_type(contents, 'metrics', Array)
      contents['metrics'].each do |m|
        parsed = MetricDefinition.create_and_fill m
        if parsed != false
          metrics.push(parsed)
        else
          warn "Failed to parse #{m}."
        end
      end
      metrics
    end
  end
end