原理：通过请求头埋入指定服务的metadata标识，扩展ribbon的choose策略。

一定要注意hystrix的隔离策略
！！强烈推荐使用信号量隔离。因为一旦使用线程隔离（线程池存在复用），会导致InheritThreadLocal（只会在线程init时拷贝父线程的ThreadLocal值）失效。

下载源码编译

应用集成

maven依赖

<dependency>
  <groupId>io.jmnarloch</groupId> 
  <artifactId>ribbon-discovery-filter-spring-cloud-starter</artifactId>
  <version>2.1.0</version>
</dependency>

应用配置

#AB测试用，网关会根据该参数路由
spring.cloud.nacos.discovery.metadata.launcher=A

拦截器

public class AbTestingFilter extends OncePerRequestFilter {
    private final static String SWITCH_KEY = "launcher",
            SWITCH_HEAD_KEY = "switchTag",
            DEFAULT_ENV = "B";//默认B为线上测试环境
    @Value("${spring.cloud.nacos.discovery.metadata.launcher}")
    private String launcherTag;

    @Override
    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        String switchTag = httpServletRequest.getHeader(SWITCH_HEAD_KEY);
        log.info("head switch tag = {}", switchTag);
        try {
            //不能调度,因为调用链路出现了不一致
            if (!launcherTag.equals(switchTag)) {
                //返回错误即可
                return;
            }
            // 开启ribbon的灰度开关（线程级别）
            RibbonFilterContextHolder.getCurrentContext().add(SWITCH_KEY, switchTag);
            filterChain.doFilter(httpServletRequest, httpServletResponse);
        } finally {
            if (DEFAULT_ENV.equals(switchTag))
                RibbonFilterContextHolder.getCurrentContext().remove(SWITCH_KEY);
        }
    }
}

feign conf
增加请求头,自定义全局的feign interceptor

    @Bean
    public RequestInterceptor newRequestInterceptor(@Value("${spring.cloud.nacos.discovery.metadata.launcher:A}") String tag) {
        return requestTemplate -> requestTemplate.header("switchTag", tag);
    }

zuul网关集成

则参考如下代码

maven依赖同上

拦截器

public class TestingAbFilter extends ZuulFilter {

    @Override
    public String filterType() {
        return FilterConstants.PRE_TYPE;
    }

    @Override
    public int filterOrder() {
        return -1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        //是否需要做AB切换
        if (request.getParameter("foo") != null) {
            //重写请求头新增AB开关透传到下游服务
            ctx.addZuulRequestHeader("switchTag", "A");
            RibbonFilterContextHolder.getCurrentContext().add("launcher", "A");
        } else {
            RibbonFilterContextHolder.getCurrentContext().add("launcher", "B");
        }
        return null;
    }
}

来源：oschina

链接：https://my.oschina.net/u/4177567/blog/4406120

标签

Spring