TechReset

BOSH CLI 是BOSH命令行的入口，所有对BOSH的操作都是通过BOSH CLI进行。本文中将介绍几个常用命令的执行过程。

bosh micro deploy

bosh micro deploy用于部署micro bosh，该命令是扩展的bosh cli 命令，来自包bosh_cli_plugin_micro. 命令入口在/bosh_cli_plugin_micro/lib/bosh/cli/commands/micro.rb. bosh micro deploy的具体对应的方法为Bosh::Cli::Command::Micro#perform 代码片段如下，可查看详细代码

def perform(stemcell=nil)
  update = !!options[:update]

  manifest = load_yaml_file(deployment)
		...
  if update
  	...
    method = :update_deployment
  else
    ...
    method = :create_deployment
  end

  confirm_deployment("#{confirmation} micro BOSH instance #{desc}")
  ...
  deployer.send(method, stemcell)
  ...
  update_target
  ...
end

其中deployer方法返回的Bosh::Deployer::InstanceManager实例，根据IaaS类型有[openstack,aws,vcloud,vsphere]四种，详细代码在/lib/deployer/instance_manager/目录下。代码片段如下

def deployer(manifest_filename=nil)
  ...
  if @deployer.nil?
    ...
    @deployer = Bosh::Deployer::InstanceManager.create(manifest)
  end

  @deployer
end

以及Bosh::Deployer::InstanceManager.create方法

class << self

  include Helpers

  def create(config)
    plugin = cloud_plugin(config)

    begin
      require "deployer/instance_manager/#{plugin}"
    rescue LoadError
      err "Could not find Provider Plugin: #{plugin}"
    end
    Bosh::Deployer::InstanceManager.const_get(plugin.capitalize).new(config)
  end

end

bosh micro deploy基本过程就是加载deployment文件->新建Bosh::Deployer::InstanceManager::Openstack实例，然后执行其update_deployment或create_deployment方法。这里我们深入查看create方法。该方法核心在于Bosh::Deployer::InstanceManager#create方法，代码如下:

def create(stemcell_tgz)
	...
  state.stemcell_cid = create_stemcell(stemcell_tgz) //1
  state.stemcell_name = File.basename(stemcell_tgz, ".tgz")
  save_state

  step "Creating VM from #{state.stemcell_cid}" do
    state.vm_cid = create_vm(state.stemcell_cid)
    update_vm_metadata(state.vm_cid, {"Name" => state.name})
    discover_bosh_ip
  end
  save_state

  step "Waiting for the agent" do
    wait_until_agent_ready
  end

  step "Updating persistent disk" do
    update_persistent_disk
  end

  unless @apply_spec
    step "Fetching apply spec" do
      @apply_spec = Specification.new(agent.release_apply_spec)
    end
  end

  apply

  step "Waiting for the director" do
    wait_until_director_ready
  end
end

由此可见，在create方法时，deployer的过程如下：

create_stemcell : 验证并上传stemcell到openstack glance
create_vm : 新建vm
update_vm_metadata : 通过openstack registry更新vm的metadata
discover_bosh_ip : 分配floating ip给vm
wait_until_agent_ready : 等待vm的agent ready，通过agent_client发送请求
update_persistent_disk : 给vm添加volume
@apply_spec = Specification.new(agent.release_apply_spec) : microbosh的stemcell与bosh不同，在/var/vcap/micro/apply_spec.yml目录下有基本的配置信息，此步骤取回该信息并调整其适合openstack的环境
apply : 上传spec给agent, 使agent根据spec执行操作。
wait_until_director_ready : 等待vm的director进行成功响应

与此同时，在vm instance上的agent随着vm启动而启动，代码片段如下

module Bosh::Agent

  BOSH_APP = BOSH_APP_USER = BOSH_APP_GROUP = "vcap"

  class << self
    def run(options = {})
      Runner.new(options).start
    end
  end

  class Runner < Struct.new(:config)

    def initialize(options)
      self.config = Bosh::Agent::Config.setup(options)
      @logger     = Bosh::Agent::Config.logger
    end

    def start
      $stdout.sync = true
      @logger.info("Starting agent #{Bosh::Agent::VERSION}...")

      if Config.configure
        @logger.info("Configuring agent...")
        Bosh::Agent::Bootstrap.new.configure

        Bosh::Agent::Monit.enable
        Bosh::Agent::Monit.start
        Bosh::Agent::Monit.start_services
      else
        @logger.info("Skipping configuration step (use '-c' argument to configure on start) ")
      end

      if Config.mbus.start_with?("https")
        @logger.info("Starting up https agent")
        require "bosh_agent/http_handler"
        Bosh::Agent::HTTPHandler.start
      else
        Bosh::Agent::Handler.start
      end
    end
  end

end

其中Bosh::Agent::Bootstrap.new.configure代码如下

def configure
      logger.info("Configuring instance")

      load_settings
      logger.info("Loaded settings: #{@settings.inspect}")

      if @settings
        update_iptables
        update_passwords
        update_agent_id
        update_credentials
        update_hostname
        update_mbus
        update_blobstore
        setup_networking
        update_time
        setup_data_disk
        setup_tmp

        Bosh::Agent::Monit.setup_monit_user
        Bosh::Agent::Monit.setup_alerts

        mount_persistent_disk
        harden_permissions
      end
      { "settings" => @settings }
    end

由此可见，当agent获取了configuration信息后，做了这么几个步骤

load_settings : load setting from openstack_registry
update_iptables
update_passwords
update_agent_id
update_credentials
update_hostname
update_mbus
update_blobstore
setup_networking
update_time : ntp
setup_data_disk : mount Ephemeral disk
setup_tmp
mount_persistent_disk : mount persistent disk (此时并没有设定persistent disk，在agent HTTP handler start之后会更新)
monit enable/start/startservice
Bosh::Agent::HTTPHandler.start/Bosh::Agent::Handler.start

在deployer和agent交互的同时，一方面deployer利用agent_client向agent发送命令，并等待执行结束，另一方面由openstack执行的操作，都是通过openstack_cpi线程执行，并通知openstack registry，agent在执行时会从openstack registry获取配置信息，并执行deployer发来的指令。