Openstack设计与实现阅读笔记

Posted by Xuan Peng on September 14, 2019

OpenStack设计与实现阅读笔记

  • OpenStack is implemented according to Amazon Web Service. AWS
  • 与运行在物理节点上的hypervisor进行交互，实现对硬件资源的管理和控制
  • Nova - ec2
  • swift - s3
  • cinder - ebs
  • keystone - iam

Componenrt Overview

Nova

  • provide VM service. The overall controller. Compatible to EC2 api as well.
  • Nova components:
    1. Nova-api: provide services to outside (including both client-user and admin). Compatible with AWS EC2 API
    2. Nova-compute: the process installed in every physical node. It receives request and translate the request to a set of operations provided by the API from Hypervisor. For example:
      • Hypervisor XenServer - XenAPI
      • KVM, QEMU - libvirt
      • VMware - VMware api
    3. Nova-scheduler: receives the request of creating a new VM and decide which physical node will be chosen as the place.
    4. Nova-conductor: between Nova-compute and Nova-db, served as the forwarding role.
    5. Nova-db: contains a lot of DB tables to record the state of VM, the mappings of VM and physic nodes and the infos of tenants.
    6. Nova-console/Nova-consoleauth: the services that allows the user to access the console of the VMs
    7. Nova-cert and Nova-objectstore

Swift - object storage

  • used to stored and retrieve object
  • Swift components
    1. Proxy-server: between the inside and outside of Swift. It receives api or HTTP requests like uploading, modifying metadata and creating a container.
    2. Account-server: used for account management
    3. Container-server: manage the mappings between containers to directories.
    4. Object-server: manage the object stored on the storing node, like files.

Keystone - Identity service

  • Provide services of certification and authorization for users and manage their privileges. Giving a list of available services
  • Keystone components:
    1. Keystone-API: receives requests
    2. Keystone-db

Cinder - Volume storage

  • Cinder-api: receives requests and forwarding them to Cinder-volume
  • CInder-volume: Interact with the lower-level block storage service. Different Storage service provider implemented different driver for Cinder-volume,
  • Cinder-scheduler: Like Nova-scheduler, to determine which storage node should be chosen for creating a new volume.
  • Cinder-db: maintain inner infos.

Neutron - Network service

  • Provides support for net-device providers via ‘plugins’
  • Neutron components:
    1. Neutron-server: receives API requests and forwarding them to corresponding neutron plugin

Glance - image service

  • Provides services of storing, retrieving and searching for images

**a classic paragraph to desc the relationships btw components **

image-20190914025158498

  • 插播：看了linus torvalds早年在google做的git宣传pre，发现原来linus是个narcissist hhhh. Git的设计理念确实很强：分布式+branch的想法让不同expertise的人各司其职。

  • 橡皮鸭调试法hhhhh

  • image-20190914163625725

  • image-20190914225046493

    • 虚拟化的主流实现方式

      1. 直接在硬件驱动上进行封装(Xen)
      2. 在操作系统上进行封装(KVM, VirtualBox)

      image-20190914225620568

    • 主流虚拟化服务提供商

      1. VMware, 基于操作系统的虚拟化
      2. Xen，通过修改linux kernel，实现硬件的虚拟化
      3. KVM，也是基于硬件的虚拟化，作为模块运行在linux内核上

    • 虚拟化管理工具：VMM本身只提供虚拟化的基础架构，最后和用户相关的工作还是要通过虚拟化管理工具来实现

      1. XenAPI image-20190914231537188
      2. libvirt image-20190914231647429

    • RESTful: Representation State Transfer表现层状态迁移

      • 用URI表示资源，用HTML谓词（get, post, delete, update, etc.）表示描述操作

    • 协程(coroutine): 是进城的子单位

      1. 拥有自己的栈和局部变量
      2. 与统一进程下的其他协程共享全局变量
      3. 与线程不一样：不会并发执行，而是被执行协程阻塞了，另一个协程接手执行
      4. 不需要考虑锁的问题，舒服
      5. 执行顺序和时间长短由用户自己决定，舒服（线程由OS决定）
      6. 本质是线程内的伪并发

    • Eventlet: python lib to provide coroutine support

Nova

  • architecture image-20190915005250712
  • four core module:
    1. API
    2. compute: interact with VMM
    3. scheduler: choose the phy node to deploy new VM
    4. conductor: abstraction for DB acces
      • Communicate through AMQP(advanced message queue protocol)
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