This will use Stuart's retention service (which pulls from Redis and stores in Cassandra) to get DAU for the specified dates and apps.

dau.rb

require 'faraday'
require 'faraday_middleware'
require 'active_support/all'

def period(app_id, start_date, end_date)
  date = start_date
  results = []
  while date <= end_date do
    results << { date: date.strftime("%F"), dau: day(app_id, date) }
    date = (date + 1)
  end
  results
end

def day(app_id, date)
  results = get("/api/v1/apps/#{app_id}/active-users", start: date.strftime("%F"), end: date.strftime("%F"))
  results["active_users"]
end

def get(path, params = nil)
  path = "#{path}?#{params.to_param}" if params
  request(path)
end

def request(path, params = nil)
  response = faraday.get(path, params)

  case response.status
  when 200..299
    JSON.parse(response.body)
  when 401
    { "error" => "Unauthorized" }
  else
    raise ServiceException, "Error making request to EKG: #{response.status}: #{response.body}"
  end
end

def faraday
  @faraday ||= Faraday.new("http://internal-af7ff2860324d11e6b25e0a4adb5302e-1847371008.us-east-1.elb.amazonaws.com/api/v1") do |config|
    # config.response :json
    config.adapter Faraday.default_adapter
  end
end

start_date = Date.parse("2016-12-01")
end_date = Date.parse("2016-12-10")

["54233298c74eda808c000434"].each do |app_id|
  period(app_id, start_date, end_date).each do |datum|
    puts [app_id, datum[:date], datum[:dau]].join(', ')
  end
end