3、网关和BFF

一、网关和BFF的演进

1. v1 使用nginx负载均衡简单的微服务体系；

   

2. v2 nginx直接暴露

3. v2.5无线BFF

4. v3 集群BFF+无线网关

5. v4无线网关、无线BFF根据业务集群化，废弃nginx集群

   二、网关和反向代理

网关和反向代理的选择：

关于网关集群问题：需要根据公司业务大小进行选择 

 三、设计简单网关-faraday

1.核心思想

2.代码实现

• 路由映射表模块 

  • MappingsProvider路由映射表

    package xyz.staffjoy.faraday.core.mappings;
     
    import com.github.structlog4j.ILogger;
    import com.github.structlog4j.SLoggerFactory;
    import org.springframework.boot.autoconfigure.web.ServerProperties;
    import xyz.staffjoy.faraday.config.FaradayProperties;
    import xyz.staffjoy.faraday.config.MappingProperties;
    import xyz.staffjoy.faraday.core.http.HttpClientProvider;
     
    import javax.annotation.PostConstruct;
    import javax.servlet.http.HttpServletRequest;
    import java.util.List;
    import java.util.stream.Collectors;
     
    import static org.springframework.util.CollectionUtils.isEmpty;
     
    public abstract class MappingsProvider {
     
        private static final ILogger log = SLoggerFactory.getLogger(MappingsProvider.class);
     
        protected final ServerProperties serverProperties;
        protected final FaradayProperties faradayProperties;
        protected final MappingsValidator mappingsValidator;
        protected final HttpClientProvider httpClientProvider;
        protected List mappings;
     
        public MappingsProvider(
                ServerProperties serverProperties,
                FaradayProperties faradayProperties,
                MappingsValidator mappingsValidator,
                HttpClientProvider httpClientProvider
        ) {
            this.serverProperties = serverProperties;
            this.faradayProperties = faradayProperties;
            this.mappingsValidator = mappingsValidator;
            this.httpClientProvider = httpClientProvider;
        }
     
        public MappingProperties resolveMapping(String originHost, HttpServletRequest request) {
            if (shouldUpdateMappings(request)) {
                updateMappings();
            }
            List resolvedMappings = mappings.stream()
                    .filter(mapping -> originHost.toLowerCase().equals(mapping.getHost().toLowerCase()))
                    .collect(Collectors.toList());
            if (isEmpty(resolvedMappings)) {
                return null;
            }
            return resolvedMappings.get(0);
        }
     
        @PostConstruct
        protected synchronized void updateMappings() {
            List newMappings = retrieveMappings();
            mappingsValidator.validate(newMappings);
            mappings = newMappings;
            httpClientProvider.updateHttpClients(mappings);
            log.info("Destination mappings updated", mappings);
        }
     
        protected abstract boolean shouldUpdateMappings(HttpServletRequest request);
     
        protected abstract List retrieveMappings();
    }
    

    resolveMapping：根据主机头获取路由映射；

    updateMappings：更新路由表；

• http映射表
  • 根据路由映射表获取到的路由，通过http映射表对目标服务发起调用

    package xyz.staffjoy.faraday.core.http;
     
    import org.apache.http.impl.client.CloseableHttpClient;
    import org.apache.http.impl.client.HttpClientBuilder;
    import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
    import org.springframework.web.client.RestTemplate;
    import xyz.staffjoy.faraday.config.MappingProperties;
     
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
     
    import static java.util.stream.Collectors.toMap;
    import static org.apache.http.impl.client.HttpClientBuilder.create;
     
    public class HttpClientProvider {
        protected Map httpClients = new HashMap<>();
     
        public void updateHttpClients(List mappings) {
            httpClients = mappings.stream().collect(toMap(MappingProperties::getName, this::createRestTemplate));
        }
     
        public RestTemplate getHttpClient(String mappingName) {
            return httpClients.get(mappingName);
        }
     
        protected RestTemplate createRestTemplate(MappingProperties mapping) {
            CloseableHttpClient client = createHttpClient(mapping).build();
            HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory(client);
            requestFactory.setConnectTimeout(mapping.getTimeout().getConnect());
            requestFactory.setReadTimeout(mapping.getTimeout().getRead());
            return new RestTemplate(requestFactory);
        }
     
        protected HttpClientBuilder createHttpClient(MappingProperties mapping) {
            return create().useSystemProperties().disableRedirectHandling().disableCookieManagement();
        }
    }
    

四、大型网关扩展

• 限流熔断：保障用户体验，保障服务不会挂断
• 动态路由和负载均衡：当服务多时，采用动态服务发现机制，k8s内部支持
• 基于Path的路由：通过域名映射到服务
• 截获器链：多个截获器构成的链状
• 日志采集和Metrics埋点：日志+日志分析；掌握后台性能状况
• 响应流优化：响应速度大时，内核态无需拷贝到用户态，直接以流的形式提供给网关

五、主流网关概览