5使用Ribbon完成应用灰度发布

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使用Ribbon完成应用灰度发布

定义RibbonRequestContext

public class RibbonRequestContext {

    private final Map<String, String> attr = new HashMap<>();

    public String put(String key, String value) {
        return attr.put(key, value);
    }

    public String remove(String key) {
        return attr.remove(key);
    }

    public String get(String key) {
        return attr.get(key);
    }

}

维护一个map，用于透传解析的请求信息。

RibbonRequestContextHolder：

public class RibbonRequestContextHolder {

    private static ThreadLocal<RibbonRequestContext> holder = new ThreadLocal<RibbonRequestContext>() {
        @Override
        protected RibbonRequestContext initialValue() {
            return new RibbonRequestContext();
        }
    };

    public static RibbonRequestContext getCurrentContext() {
        return holder.get();
    }

    public static void setCurrentContext(RibbonRequestContext context) {
        holder.set(context);
    }

    public static void clearContext() {
        holder.remove();
    }

}

持有自定义的RibbonRequestContext

然后定义GrayRequestInterceptor

public class GrayInterceptor implements ClientHttpRequestInterceptor {

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
        throws IOException {
        if (request.getHeaders().containsKey("Gray")) {
            String value = request.getHeaders().getFirst("Gray");
            if (value.equals("true")) {
                RibbonRequestContextHolder.getCurrentContext().put("Gray", Boolean.TRUE.toString());
                ServletRequestAttributes attributes = (ServletRequestAttributes)RequestContextHolder.getRequestAttributes();
                attributes.setAttribute("Gray", Boolean.TRUE.toString(), 0);
            }
        }
        return execution.execute(request, body);
    }

}

GrayRequestInterceptor加入到RestTemplate

		@Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.getInterceptors().add(new GrayInterceptor());
        return restTemplate;
    }

		@Bean
    public IRule myRule() {
        return new GrayRule();
    }

自定义IRule：

ublic class GrayRule extends AbstractLoadBalancerRule {

    private Random random = new Random();

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {

    }

    @Override
    public Server choose(Object key) {
        boolean grayInvocation = false;
        try {
            String grayTag = RibbonRequestContextHolder.getCurrentContext().get("Gray");
            if(!StringUtils.isEmpty(grayTag) && grayTag.equals(Boolean.TRUE.toString())) {
                grayInvocation = true;
            }

            List<Server> serverList = this.getLoadBalancer().getReachableServers();
            List<Server> grayServerList = new ArrayList<>();
            List<Server> normalServerList = new ArrayList<>();
            for(Server server : serverList) {
                NacosServer nacosServer = (NacosServer) server;
                if(nacosServer.getMetadata().containsKey("gray") && nacosServer.getMetadata().get("gray").equals("true")) {
                    grayServerList.add(server);
                } else {
                    normalServerList.add(server);
                }
            }

            if(grayInvocation) {
                return grayServerList.get(random.nextInt(grayServerList.size()));
            } else {
                return normalServerList.get(random.nextInt(normalServerList.size()));
            }
        } finally {
            RibbonRequestContextHolder.clearContext();
        }
    }

}

服务提供者通过spring.cloud.nacos.discovery.metadata.gray=false 配置项决定元数据内容

最后发起服务调用的时候传递Header中的Gray信息，如果为true，只会路由到灰度实例，否则路由到正常实例。

OpenFeign配置拦截：

public class GrayRequestInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        if (template.headers().containsKey("Gray")) {
            String value = template.headers().get("Gray").iterator().next();
            if (value.equals("true")) {
                RibbonRequestContextHolder.getCurrentContext().put("Gray", Boolean.TRUE.toString());
            }
        }
    }
}