issues.rb

require 'octokit'
require 'csv'

client = Octokit::Client.new(access_token: 'ACCESS_TOKEN')
client.auto_paginate = true
open = client.issues('namely/issues', headers: { 'x-oauth-basic' => 'ACCESS_TOKEN' })
closed = client.issues('namely/issues', headers: { 'x-oauth-basic' => 'ACCESS_TOKEN' }, state: 'closed')
issues = open + closed

CSV.open("filename.csv", "wb") do |csv|
  # Github API Documentation on Issues: https://developer.github.com/v3/issues/ 
  csv << ['number', 'title', 'user', 'labels', 'state', 'assignee', 'milestone', 'created_at', 'closed_at']

  issues.each do |issue|
    hash = issue.to_hash
    csv << [
      hash[:number],
      hash[:title],
      hash[:user][:login],
      hash[:labels].collect { |label| label[:name] }.join(' ,'),
      (hash[:assignee] || {})[:login] || '',
      hash[:milsetone],
      hash[:created_at],
      hash[:closed_at]
    ]
  end
end