docker build script

rolling_update.rb

require 'json'
require 'http'

APP_NAME = ENV['APP_NAME']
DEPLOY_COUNT = ENV['DEPLOY_COUNT']
INNER_PORT = ENV['INNER_PORT']
EXPORT_PORT_START = ENV['EXPORT_PORT_START']

NGINX_CONFIG_PATH = '/etc/nginx/sites/'

class Container
  attr_accessor :image, :container_id, :port
end

# return running containers with name and container id
def current_running
  `docker ps --format='{{json .}}'`.split("\n").map do |j|
    m = JSON.parse(j)
    next unless m['Names'].include?(APP_NAME)
    Container.new.tap do |r|
      r.image, r.port = m['Names'].gsub(APP_NAME, '').split('.').map(&:to_i)
      r.container_id = m['ID']
    end
  end.compact.sort_by(&:port)
end

def port_occupied?(containers, port)
  containers.each do |c|
    return true if c.port == port
  end
  false
end

def start_container(container)
  `docker run --publish=#{container.port}:#{INNER_PORT} --detach=true --name=#{APP_NAME}#{container.image}.#{container.port} --restart=always #{APP_NAME}:#{container.image}`
  puts "start container on port #{container.port}"
  sleep 2
end

def health_check(container, retry_time=5)
  res = HTTP.get("http://localhost:#{container.port}/health").to_s
  if res != 'ok'
    puts "http not health, abort deployment, please check configurations"
    exit(1)
  end
rescue
  if retry_time > 0
    sleep 2
    puts "retry health check"
    health_check(container, retry_time - 1)
  else
    puts "can't connect http health check on container #{container.container_id}|#{container.port} after 5 times try, abort deployment"
    exit(1)
  end
end

def stop_container(container)
  return if container.nil?
  `docker container stop #{container.container_id}`
  # remove it to make sure no duplicate name when rolling back
  `docker container rm #{container.container_id}`
  puts "stop container #{container.container_id} on port #{container.port}"
end

def upstream_conf(containers)
  header = "upstream #{APP_NAME}_server {"
  body = containers.map do |c|
    "    server 127.0.0.1:#{c.port};"
  end
  footer = "}"
  [header, body, footer].flatten.join("\n")
end

def nginx_conf_file
  NGINX_CONFIG_PATH + "#{APP_NAME}.conf"
end

def update_nginx_upstream(containers)
  new_content = File.read(nginx_conf_file).gsub!(/upstream #{APP_NAME}_server {.*?}/m, upstream_conf(containers))
  File.write(nginx_conf_file, new_content)
  `nginx -s reload`
end

def rolling_update(image)
  pendings = []
  runnings = current_running
  (EXPORT_PORT_START.to_i ... (EXPORT_PORT_START.to_i+100)).each do |port|
    if !port_occupied?(runnings, port)
      break if pendings.length >= DEPLOY_COUNT.to_i
      container = Container.new.tap do |c|
        c.image = image
        c.port = port
      end
      pendings << container

      start_container(container)
      health_check(container)

      need_remove = runnings.shift

      update_nginx_upstream(pendings + runnings)
      stop_container(need_remove)
    end
  end

  while !(r = runnings.shift).nil?
    update_nginx_upstream(pendings + runnings)
    stop_container(r)
  end
end

def usage 
  puts "Usage: rolling-update.rb command ...args"
  puts "  upgrade image: rolling-update.rb upgrade [image_tag_version]"
  puts "  get rollback version list: rolling-update.rb rollback list"
  puts "  rollback to specified version: rolling-update.rb rollback [image_tag_version]"
  exit
end

def main(args)
  usage if args.length == 0

  case args[0]
  when 'upgrade'
    usage if args.length == 1
    rolling_update(args[1])
  when 'rollback'
    usage if args.length == 1
    if args[1] == 'list'
      puts `docker images #{APP_NAME} | grep #{APP_NAME} | awk '{print $2}' | sort -r`
      exit
    end
    rolling_update(args[1])
  else
    usage
  end
end

def check_env_by_name!(name)
  if !ENV[name]
    puts "please set #{name} env"
    exit(1)
  end
end

def check_env!
  %w(APP_NAME DEPLOY_COUNT INNER_PORT EXPORT_PORT_START).each do |name|
    check_env_by_name!(name)
  end
end

def check_nginx_conf_path!
  if !File.exist?(nginx_conf_file)
    puts "nginx conf file not exist, please check #{nginx_conf_file}"
    exit(1)
  end
end

check_env!
check_nginx_conf_path!
main(ARGV)