class Aws::Rails::EbsSqsActiveJobMiddleware

Middleware to handle requests from the SQS Daemon present on Elastic Beanstalk worker environments.

def app_runs_in_docker_container? 

def app_runs_in_docker_container?
  @app_runs_in_docker_container ||= `[ -f /proc/1/cgroup ] && cat /proc/1/cgroup` =~ /docker/
end

def call(env) 

def call(env)
  request = ActionDispatch::Request.new(env)
  # Pass through unless user agent is the SQS Daemon
  return @app.call(env) unless from_sqs_daemon?(request)
  @logger.debug('aws-sdk-rails middleware detected call from Elastic Beanstalk SQS Daemon.')
  # Only accept requests from this user agent if it is from localhost or a docker host in case of forgery.
  unless request.local? || sent_from_docker_host?(request)
    @logger.warn("SQSD request detected from untrusted address #{request.ip}; returning 403 forbidden.")
    return FORBIDDEN_RESPONSE
  end
  # Execute job or periodic task based on HTTP request context
  periodic_task?(request) ? execute_periodic_task(request) : execute_job(request)
end

def default_gw_ips 

def default_gw_ips
  default_gw_ips = ['172.17.0.1']
  if File.exist?('/proc/net/route')
    File.open('/proc/net/route').each_line do |line|
      fields = line.strip.split
      next if fields.size != 11
      # Destination == 0.0.0.0 and Flags & RTF_GATEWAY != 0
      if fields[1] == '00000000' && (fields[3].hex & 0x2) != 0
        default_gw_ips << IPAddr.new_ntoh([fields[2].hex].pack('L')).to_s
      end
    end
  end
  default_gw_ips
end

def execute_job(request) 

def execute_job(request)
  # Jobs queued from the Active Job SQS adapter contain the JSON message in the request body.
  job = Aws::Json.load(request.body.string)
  job_name = job['job_class']
  @logger.debug("Executing job: #{job_name}")
  begin
    ActiveJob::Base.execute(job)
  rescue NoMethodError, NameError => e
    @logger.error("Job #{job_name} could not resolve to a class that inherits from Active Job.")
    @logger.error("Error: #{e}")
    return INTERNAL_ERROR_RESPONSE
  end
  [200, { 'Content-Type' => 'text/plain' }, ["Successfully ran job #{job_name}."]]
end

def execute_periodic_task(request) 

def execute_periodic_task(request)
  # The beanstalk worker SQS Daemon will add the 'X-Aws-Sqsd-Taskname' for periodic tasks set in cron.yaml.
  job_name = request.headers['X-Aws-Sqsd-Taskname']
  @logger.debug("Creating and executing periodic task: #{job_name}")
  begin
    job = job_name.constantize.new
    job.perform_now
  rescue NoMethodError, NameError => e
    @logger.error("Periodic task #{job_name} could not resolve to an Active Job class - check the spelling in cron.yaml.")
    @logger.error("Error: #{e}.")
    return INTERNAL_ERROR_RESPONSE
  end
  [200, { 'Content-Type' => 'text/plain' }, ["Successfully ran periodic task #{job_name}."]]
end

def from_sqs_daemon?(request)

The beanstalk worker SQS Daemon sets a specific User-Agent headers that begins with 'aws-sqsd'. 
def from_sqs_daemon?(request)
  current_user_agent = request.headers['User-Agent']
  !current_user_agent.nil? && current_user_agent.start_with?('aws-sqsd')
end

def initialize(app) 

def initialize(app)
  @app = app
  @logger = ::Rails.logger
end

def periodic_task?(request)

The beanstalk worker SQS Daemon will add the custom 'X-Aws-Sqsd-Taskname' header for periodic tasks set in cron.yaml. 
def periodic_task?(request)
  !request.headers['X-Aws-Sqsd-Taskname'].nil? && request.headers['X-Aws-Sqsd-Taskname'].present?
end

def sent_from_docker_host?(request) 

def sent_from_docker_host?(request)
  app_runs_in_docker_container? && default_gw_ips.include?(request.ip)
end