在数据库表中设计一个【灰度发布启用表】（也可以用Apollo配置中心，Redis，Zookeeper实现）。

代码示例

  1. id    |        service_id    |        path    |        enable_gray_release
  2.                         服务ID            路径                是否启用灰度发布
  5. CREATE TABLE `gray_release_config` (
  6.    `id` int(11) NOT NULL AUTO_INCREMENT,
  7.    `service_id` varchar(255) DEFAULT NULL,
  8.    `path` varchar(255) DEFAULT NULL,
  9.    `enable_gray_release` int(11) DEFAULT NULL,
  10.    PRIMARY KEY (`id`)
  11.  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
  1. ## 在zuul里面加入下面的fiter包，可以在zuul的filter里定制ribbon的负载均衡策略
  3. <dependency>
  4.   <groupId>io.jmnarloch</groupId>
  5.   <artifactId>ribbon-discovery-filter-spring-cloud-starter</artifactId>
  6.   <version>2.1.0</version>
  7. </dependency>
  1. ## 写一个zuul的filter，对每一个请求，zuul都会调用这个filter
  3. @Configuration
  4. public class GrayReleaseFilter extends ZuulFilter {
  6. @Autowired
  7. private JdbcTemplate jdbcTemplate;
  9.     @Override
  10.     public int filterOrder() {
  11.         return PRE_DECORATION_FILTER_ORDER - 1;
  12.     }
  14.     @Override
  15.     public String filterType() {
  16.         return PRE_TYPE;
  17.     }
  19.     @Override
  20.     public boolean shouldFilter() {
  22.     }
  24.     @Override
  25.     public Object run() {
  26.         RequestContext ctx = RequestContext.getCurrentContext();
  27.         HttpServletRequest request = ctx.getRequest();
  29. Random random = new Random();
  30. int seed = random.getInt() * 100;
  32.         if (seed = 50) {
  33.             // put the serviceId in `RequestContext`
  34.             RibbonFilterContextHolder.getCurrentContext()
  35.                     .add("version", "new");
  36.         }  else {
  37.             RibbonFilterContextHolder.getCurrentContext()
  38.                     .add("version", "old");
  39.         }
  41.         return null;
  42.     }
  43. }

逻辑流程图