Using Amazon Elasticsearch securely (signed requests) with Rails & searchkick gem on Heroku.

elasticsearch.rb

# config/initializers/elasticsearch.rb
# ensure you set AWS_ES_URL, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY
# change region as needed

require 'patron'
require 'faraday_middleware/aws_signers_v4'

class AmazonElasticSearchClient
  def self.client
    return Elasticsearch::Client.new(url: ENV['AWS_ELASTICSEARCH_URL']) do |f|
      f.request_timeout = 15
      f.request :aws_signers_v4,
                credentials: Aws::Credentials.new(ENV['AWS_ACCESS_KEY_ID'], ENV['AWS_SECRET_ACCESS_KEY']),
                service_name: ENV['AWS_ELASTICSEARCH_SERVICE_NAME'],
                region: ENV['AWS_REGION']
    end
  end
end

Elasticsearch::Model.client = AmazonElasticSearchClient.client unless ENV["AWS_ELASTICSEARCH_URL"].blank?

Gemfile

gem 'elasticsearch', '>= 1.0.15'
gem 'elasticsearch-model'
gem 'elasticsearch-rails'
gem 'patron'
gem 'faraday_middleware-aws-signers-v4'
gem 'searchkick'