Practical Microservices-Packt Publishing(2017) 读书笔记

Practical Microservices-Packt Publishing(2017)-ReadingNotes.md

微服务架构介绍

• boot2docker依赖于VirtualBox？那么docker的图形化界面app呢？docker命令是否自动从hub上下载镜像？
• Spring Boot：从maven pom.xml文件开始吗？starter项目可以自动生成的吧？

定义微服务组件

• 发现服务：
  • Etcd by CoreOS
  • Eureka by Netflix
  • Consul by HashiCorp
  • Apache ZooKeeper
  • SkyDNS
  • SmartStack by Airbnb
• Self-registration
• 客户端发现：如Netflix Eureka，这违反了单一职责原则
  • vs 服务器端发现：LB网关
• 外部化配置：NFS or AWS S3
  • Spring Boot属性查找顺序：*
    1. 命令行参数
    2. SPRING_APPLICATION_JSON环境变量
    3. JNDI java:comp/env
    4. System.getProperties()
    5. OS特定的环境变量
    6. RandomValuePropertySources ？
    7. application-{profile}.properties ？
    8. “Application properties inside/outside of your packaged JAR
    9. @PropertySource 支持从多个文件中加载？
    10. SpringApplication.setDefaultProperties
• API网关 (缺点：...)
  • 认证
  • 不同协议的适配
  • LB
  • Response transform
  • Circuit breaker：Hystrix (by Netflix)，5秒内20个失败请求，fall back to dummy
  • 例子：Zuul
    • 生成初始代码模板
• Sample应用：Credit risk engine
  • “Flyway is an open source database migration tool.”

   @SpringBootApplication public class UserServiceApplication {      @Value("${spring.datasource.url}")      private String url;      @Value("${spring.datasource.username}")      private String userName;      @Value("${spring.datasource.password}")      private String password;     @Bean(initMethod = "migrate")  public Flyway flyway() { ...

微服务节点间通信

• Orchestration（有leader） versus choreography（分布式自治）
  • 第一种：The mediator service
• 同步 vs 异步通信
  • 同步：断路器

   @RestController  @SpringBootApplication  @EnableCircuitBreaker  public class ConsumingApplication { @Autowired  private ConsumingService consumingService;  @RequestMapping(method = RequestMethod.POST,value = "/book/{movieId}",produces = "application/json")  public String book ticket(@PathVariable("userId") String userId, @PathVariable("movieId") String movieId){  return consumingService.bookAndRespond(userId,movieId);  } ... } @Service  public class ConsumingService {     @Autowired     private  RestTemplate restTemplate;     @HystrixCommand(fallbackMethod = "getAnotherCurentlyShowingMovie")    public String bookAndRespond() {      URI uri = URI.create("http://<application Ip:port>/bookingapplication/{userId}/{movieId}");     //？这里的userId、movieId参数是怎么注入的？？？示例代码有误？？？  return this.restTemplate.getForObject(uri, String.class);    }

  • 异步
    • “message-based works on p2p communication, and event-based works based on publisher/subscriber.”
    • “Spring has inbuilt support for Kafka, RabbitMQ, and some other messaging brokers.”

安全

• JWT（JSON Web Token）
• OpenID
• OAuth 2.0

创建有效的数据模型

• The Saga pattern（可逆的消息流）
  • routing slip

   When an activity fails, it cleans up locally and then sends the routing slip backwards to the last completed activity's compensation address to unwind the transaction outcome.

  • initiator
  • Command Query Responsibility Segregation (CQRS)
• Migrating a data model from monolithic to microservices
  • DDD
    • “For example, one user could have two or three addresses, so we need address management.”
  • Methods of data model migration
    • View
    • Clone table using trigger
    • Event sourcing（高级业务层log & replay）

     “The success of microservices architecture success lies in the secret of how good one can decompose bigger problems into smaller ones.”

测试

• “Contract testing is different as compared to integration testing”（头一回听说‘合同测试’）
  • Pact
• End-to-end testing mostly refers to testing the whole application, ...

部署

• CI/CD：POM goals？
• Linux系统上安装Docker（不像Mac／Windows那样，需要VirtualBox）
  • sudo apt-get install docker-engine
• maven-docker plugin？
  • after pom.xml edit:
    • $ mvn package docker:build
  • FROM maven:3.3-jdk-8-onbuild

现存系统的演化

• “The proper tools should be used for database migration; FlyBase and Liquibase are two such tools that will help you to upgrade your database automatically.”

监控和伸缩

• Principles in scaling a microservices system
  • 'The Art of Scalability'里的scalecube：
    • X axis：scale out
    • Y：组件分解
    • Z：“a cross between x and y scaling strategies, using a data sharding based approach.” ？
• Tools
  • QBit
  • ELK
  • Dynatrace
  • Sensu
  • AppDynamics
  • Instana
  • OpsClarity
  • 其他APM：“Prometheus, Netsil, Nagios, New Relic APM, Foglight, Compuware APM”
  • More：“etcd、Deis、Spotify Helios、Tutum、Project Atomic、Geard、Docker OpenStack、Coreos、Flynn、Tsuru”

故障排除

• “Zipkin is an open source tool developer by Twitter to trace and debug into microservice. This is inspired by Google's Dapper Idea”