SpringCloud Alibaba微服务实战三十二 - 实现网关的灰度发布

<spring-boot.version>2.4.2</spring-boot.version>
<alibaba-cloud.version>2021.1</alibaba-cloud.version>
<springcloud.version>2020.0.0</springcloud.version>

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-loadbalancer</artifactId>
</dependency>

/**
 * Description:
 * 自定义灰度
 * 通过给请求头添加Version 与 Service Instance 元数据属性进行对比
 * @author Jam
 * @date 2021/6/1 17:26
 */
@Log4j2
public class VersionGrayLoadBalancer implements ReactorServiceInstanceLoadBalancer {
    private final ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;
    private final String serviceId;
    private final AtomicInteger position;
    public VersionGrayLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {
        this(serviceInstanceListSupplierProvider,serviceId,new Random().nextInt(1000));
    }
    public VersionGrayLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider,
                                   String serviceId, int seedPosition) {
        this.serviceId = serviceId;
        this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
        this.position = new AtomicInteger(seedPosition);
    }
    @Override
    public Mono<Response<ServiceInstance>> choose(Request request) {
        ServiceInstanceListSupplier supplier = this.serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);
        return supplier.get(request).next()
                .map(serviceInstances -> processInstanceResponse(serviceInstances,request));
    }
    private Response<ServiceInstance> processInstanceResponse(List<ServiceInstance> instances, Request request) {
        if (instances.isEmpty()) {
            log.warn("No servers available for service: " + this.serviceId);
            return new EmptyResponse();
        } else {
            DefaultRequestContext requestContext = (DefaultRequestContext) request.getContext();
            RequestData clientRequest = (RequestData) requestContext.getClientRequest();
            HttpHeaders headers = clientRequest.getHeaders();
            // get Request Header
            String reqVersion = headers.getFirst("version");
            if(StringUtils.isEmpty(reqVersion)){
                return processRibbonInstanceResponse(instances);
            }
            log.info("request header version : {}",reqVersion );
   // filter service instances
            List<ServiceInstance> serviceInstances = instances.stream()
                    .filter(instance -> reqVersion.equals(instance.getMetadata().get("version")))
                    .collect(Collectors.toList());
            if(serviceInstances.size() > 0){
                return processRibbonInstanceResponse(serviceInstances);
            }else{
                return processRibbonInstanceResponse(instances);
            }
        }
    }
    /**
     * 负载均衡器
     * 参考 org.springframework.cloud.loadbalancer.core.RoundRobinLoadBalancer#getInstanceResponse
     * @author javadaily
     */
    private Response<ServiceInstance> processRibbonInstanceResponse(List<ServiceInstance> instances) {
        int pos = Math.abs(this.position.incrementAndGet());
        ServiceInstance instance = instances.get(pos % instances.size());
        return new DefaultResponse(instance);
    }
}

/**
 * Description:
 * 自定义负载均衡器配置实现类
 * @author javadaily
 * @date 2021/6/3 16:02
 */
public class VersionLoadBalancerConfiguration {
    @Bean
    ReactorLoadBalancer<ServiceInstance> versionGrayLoadBalancer(Environment environment,
                                                                 LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new VersionGrayLoadBalancer(
                loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
    }
}

/**
 * 自定义服务实例筛选逻辑
 * @author javadaily
 * 参考：org.springframework.cloud.loadbalancer.core.ZonePreferenceServiceInstanceListSupplier
 */
@Log4j2
public class VersionServiceInstanceListSupplier extends DelegatingServiceInstanceListSupplier {
    public VersionServiceInstanceListSupplier(ServiceInstanceListSupplier delegate) {
        super(delegate);
    }
    @Override
    public Flux<List<ServiceInstance>> get() {
        return delegate.get();
    }
    @Override
    public Flux<List<ServiceInstance>> get(Request request) {
        return delegate.get(request).map(instances -> filteredByVersion(instances,getVersion(request.getContext())));
    }
    /**
     * filter instance by requestVersion
     * @author javadaily
     */
    private List<ServiceInstance> filteredByVersion(List<ServiceInstance> instances, String requestVersion) {
        log.info("request version is {}",requestVersion);
        if(StringUtils.isEmpty(requestVersion)){
            return instances;
        }
        List<ServiceInstance> filteredInstances = instances.stream()
                .filter(instance -> requestVersion.equalsIgnoreCase(instance.getMetadata().getOrDefault("version","")))
                .collect(Collectors.toList());
        if (filteredInstances.size() > 0) {
            return filteredInstances;
        }
        return instances;
    }
    private String getVersion(Object requestContext) {
        if (requestContext == null) {
            return null;
        }
        String version = null;
        if (requestContext instanceof RequestDataContext) {
            version = getVersionFromHeader((RequestDataContext) requestContext);
        }
        return version;
    }
    /**
     * get version from header
     * @author javadaily
     */
    private String getVersionFromHeader(RequestDataContext context) {
        if (context.getClientRequest() != null) {
            HttpHeaders headers = context.getClientRequest().getHeaders();
            if (headers != null) {
                //could extract to the properties
                return headers.getFirst("version");
            }
        }
        return null;
    }
}

public class VersionServiceInstanceListSupplierConfiguration {
    @Bean
    ServiceInstanceListSupplier serviceInstanceListSupplier(ConfigurableApplicationContext context) {
        ServiceInstanceListSupplier delegate = ServiceInstanceListSupplier.builder()
                .withDiscoveryClient()
                .withCaching()
                .build(context);
        return new VersionServiceInstanceListSupplier(delegate);
    }
}