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本文主要研究一下spring-cloud-kubernetes-client-loadbalancer
ServiceInstanceListSupplier
org/springframework/cloud/loadbalancer/core/ServiceInstanceListSupplier.java
public interface ServiceInstanceListSupplier extends Supplier<Flux<List<ServiceInstance>>> {String getServiceId();default Flux<List<ServiceInstance>> get(Request request) {return get();}static ServiceInstanceListSupplierBuilder builder() {return new ServiceInstanceListSupplierBuilder();}}
spring-cloud-loadbalancer定义了ServiceInstanceListSupplier,它继承自Supplier,其泛型为
Flux<List<ServiceInstance>>
,它定义了getServiceId、get(Request)方法,并提供了builder静态方法
Request
org/springframework/cloud/client/loadbalancer/Request.java
public interface Request<C> {// Avoid breaking backward compatibilitydefault C getContext() {return null;}// TODO: define contents}
Request提供了getContext方法,默认返回null
DefaultRequest
org/springframework/cloud/client/loadbalancer/DefaultRequest.java
public class DefaultRequest<T> implements Request<T> {private T context;public DefaultRequest() {new DefaultRequestContext();}public DefaultRequest(T context) {this.context = context;}@Overridepublic T getContext() {return context;}public void setContext(T context) {this.context = context;}@Overridepublic String toString() {ToStringCreator to = new ToStringCreator(this);to.append("context", context);return to.toString();}@Overridepublic boolean equals(Object o) {if (this == o) {return true;}if (!(o instanceof DefaultRequest<?> that)) {return false;}return Objects.equals(context, that.context);}@Overridepublic int hashCode() {return Objects.hash(context);}}
DefaultRequest实现了Request,其定义的泛型为context的类型
ServiceInstanceListSupplier
spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/loadbalancer/KubernetesServicesListSupplier.java
public abstract class KubernetesServicesListSupplier implements ServiceInstanceListSupplier {protected final Environment environment;protected final KubernetesDiscoveryProperties discoveryProperties;protected final KubernetesServiceInstanceMapper mapper;public KubernetesServicesListSupplier(Environment environment, KubernetesServiceInstanceMapper mapper,KubernetesDiscoveryProperties discoveryProperties) {this.environment = environment;this.discoveryProperties = discoveryProperties;this.mapper = mapper;}@Overridepublic String getServiceId() {return environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);}@Overridepublic abstract Flux<List<ServiceInstance>> get();}
KubernetesServicesListSupplier声明实现ServiceInstanceListSupplier接口,它是一个抽象类,定义了get方法,这里忽略了get(Request),没有将Request传递下来
KubernetesClientServicesListSupplier
spring-cloud-kubernetes-client-loadbalancer/src/main/java/org/springframework/cloud/kubernetes/client/loadbalancer/KubernetesClientServicesListSupplier.java
public class KubernetesClientServicesListSupplier extends KubernetesServicesListSupplier {private static final Log LOG = LogFactory.getLog(KubernetesClientServicesListSupplier.class);private CoreV1Api coreV1Api;private KubernetesClientProperties kubernetesClientProperties;private KubernetesNamespaceProvider kubernetesNamespaceProvider;public KubernetesClientServicesListSupplier(Environment environment, KubernetesServiceInstanceMapper mapper,KubernetesDiscoveryProperties discoveryProperties, CoreV1Api coreV1Api,KubernetesNamespaceProvider kubernetesNamespaceProvider) {super(environment, mapper, discoveryProperties);this.coreV1Api = coreV1Api;this.kubernetesNamespaceProvider = kubernetesNamespaceProvider;}private String getNamespace() {return kubernetesNamespaceProvider != null ? kubernetesNamespaceProvider.getNamespace(): kubernetesClientProperties.namespace();}@Overridepublic Flux<List<ServiceInstance>> get() {LOG.info("Getting services with id " + this.getServiceId());List<ServiceInstance> result = new ArrayList<>();List<V1Service> services;try {if (discoveryProperties.allNamespaces()) {services = coreV1Api.listServiceForAllNamespaces(null, null, "metadata.name=" + this.getServiceId(),null, null, null, null, null, null, null, null).getItems();}else {services = coreV1Api.listNamespacedService(getNamespace(), null, null, null,"metadata.name=" + this.getServiceId(), null, null, null, null, null, null, null).getItems();}services.forEach(service -> result.add(mapper.map(service)));}catch (ApiException e) {LOG.warn("Error retrieving service with name " + this.getServiceId(), e);}LOG.info("Returning services: " + result);return Flux.defer(() -> Flux.just(result));}}
KubernetesClientServicesListSupplier继承了KubernetesServicesListSupplier,其构造器依赖KubernetesServiceInstanceMapper、KubernetesDiscoveryProperties、CoreV1Api、KubernetesNamespaceProvider;其get方法使用coreV1Api.listServiceForAllNamespaces或者coreV1Api.listNamespacedService来返回指定serviceId的V1Service信息,之后通过mapper转换为ServiceInstance
V1Service
io/kubernetes/client/openapi/models/V1Service.java
public class V1Service implements io.kubernetes.client.common.KubernetesObject {public static final String SERIALIZED_NAME_API_VERSION = "apiVersion";@SerializedName(SERIALIZED_NAME_API_VERSION)private String apiVersion;public static final String SERIALIZED_NAME_KIND = "kind";@SerializedName(SERIALIZED_NAME_KIND)private String kind;public static final String SERIALIZED_NAME_METADATA = "metadata";@SerializedName(SERIALIZED_NAME_METADATA)private V1ObjectMeta metadata;public static final String SERIALIZED_NAME_SPEC = "spec";@SerializedName(SERIALIZED_NAME_SPEC)private V1ServiceSpec spec;public static final String SERIALIZED_NAME_STATUS = "status";@SerializedName(SERIALIZED_NAME_STATUS)private V1ServiceStatus status;//......
}
V1Service定义了apiVersion、kind、metadata、spec、status属性
KubernetesServiceInstanceMapper
spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/loadbalancer/KubernetesServiceInstanceMapper.java
public interface KubernetesServiceInstanceMapper<T> {KubernetesServiceInstance map(T service);static String createHost(String serviceName, String namespace, String clusterDomain) {return String.format("%s.%s.svc.%s", serviceName, StringUtils.hasText(namespace) ? namespace : "default",clusterDomain);}static boolean isSecure(Map<String, String> labels, Map<String, String> annotations, String servicePortName,Integer servicePort) {if (labels != null) {final String securedLabelValue = labels.getOrDefault("secured", "false");if (securedLabelValue.equals("true")) {return true;}}if (annotations != null) {final String securedAnnotationValue = annotations.getOrDefault("secured", "false");if (securedAnnotationValue.equals("true")) {return true;}}return (servicePortName != null && servicePortName.endsWith("https")) || servicePort.toString().endsWith("443");}static Map<String, String> getMapWithPrefixedKeys(Map<String, String> map, String prefix) {if (map == null) {return new HashMap<>();}if (!StringUtils.hasText(prefix)) {return map;}final Map<String, String> result = new HashMap<>();map.forEach((k, v) -> result.put(prefix + k, v));return result;}}
KubernetesServiceInstanceMapper接口定义了map方法,它提供了createHost、isSecure、getMapWithPrefixedKeys静态方法
KubernetesClientServiceInstanceMapper
spring-cloud-kubernetes-client-loadbalancer/src/main/java/org/springframework/cloud/kubernetes/client/loadbalancer/KubernetesClientServiceInstanceMapper.java
public class KubernetesClientServiceInstanceMapper implements KubernetesServiceInstanceMapper<V1Service> {private KubernetesLoadBalancerProperties properties;private KubernetesDiscoveryProperties discoveryProperties;public KubernetesClientServiceInstanceMapper(KubernetesLoadBalancerProperties properties,KubernetesDiscoveryProperties discoveryProperties) {this.properties = properties;this.discoveryProperties = discoveryProperties;}@Overridepublic KubernetesServiceInstance map(V1Service service) {final V1ObjectMeta meta = service.getMetadata();final List<V1ServicePort> ports = service.getSpec().getPorts();V1ServicePort port = null;if (ports.size() == 1) {port = ports.get(0);}else if (ports.size() > 1 && StringUtils.hasText(this.properties.getPortName())) {Optional<V1ServicePort> optPort = ports.stream().filter(it -> properties.getPortName().endsWith(it.getName())).findAny();if (optPort.isPresent()) {port = optPort.get();}}if (port == null) {return null;}final String host = KubernetesServiceInstanceMapper.createHost(service.getMetadata().getName(),service.getMetadata().getNamespace(), properties.getClusterDomain());final boolean secure = KubernetesServiceInstanceMapper.isSecure(service.getMetadata().getLabels(),service.getMetadata().getAnnotations(), port.getName(), port.getPort());return new DefaultKubernetesServiceInstance(meta.getUid(), meta.getName(), host, port.getPort(),getServiceMetadata(service), secure);}private Map<String, String> getServiceMetadata(V1Service service) {final Map<String, String> serviceMetadata = new HashMap<>();KubernetesDiscoveryProperties.Metadata metadataProps = this.discoveryProperties.metadata();if (metadataProps.addLabels()) {Map<String, String> labelMetadata = KubernetesServiceInstanceMapper.getMapWithPrefixedKeys(service.getMetadata().getLabels(), metadataProps.labelsPrefix());serviceMetadata.putAll(labelMetadata);}if (metadataProps.addAnnotations()) {Map<String, String> annotationMetadata = KubernetesServiceInstanceMapper.getMapWithPrefixedKeys(service.getMetadata().getAnnotations(), metadataProps.annotationsPrefix());serviceMetadata.putAll(annotationMetadata);}return serviceMetadata;}}
KubernetesClientServiceInstanceMapper实现了KubernetesServiceInstanceMapper接口,其泛型为V1Service,其map方法先通过service.getSpec().getPorts()获取port信息,之后通过createHost返回svc的短域名
<servicename>.<namespace>.svc.<clusterdomain>
,例如service-a.default.svc.cluster.local
,最后创建DefaultKubernetesServiceInstance
KubernetesClientLoadBalancerClientConfiguration
spring-cloud-kubernetes-client-loadbalancer/src/main/java/org/springframework/cloud/kubernetes/client/loadbalancer/KubernetesClientLoadBalancerClientConfiguration.java
public class KubernetesClientLoadBalancerClientConfiguration {@Bean@ConditionalOnProperty(name = "spring.cloud.kubernetes.loadbalancer.mode", havingValue = "SERVICE")ServiceInstanceListSupplier kubernetesServicesListSupplier(Environment environment, CoreV1Api coreV1Api,KubernetesClientServiceInstanceMapper mapper, KubernetesDiscoveryProperties discoveryProperties,KubernetesNamespaceProvider kubernetesNamespaceProvider, ConfigurableApplicationContext context) {return ServiceInstanceListSupplier.builder().withBase(new KubernetesClientServicesListSupplier(environment,mapper, discoveryProperties, coreV1Api, kubernetesNamespaceProvider)).withCaching().build(context);}}
KubernetesClientLoadBalancerClientConfiguration在
spring.cloud.kubernetes.loadbalancer.mode
设置为SERVICE
的时候会自动创建kubernetesServicesListSupplier
小结
spring-cloud-loadbalancer定义了ServiceInstanceListSupplier,它继承自Supplier,其泛型为Flux<List<ServiceInstance>>
,它定义了getServiceId、get(Request)方法,并提供了builder静态方法;KubernetesServicesListSupplier声明实现ServiceInstanceListSupplier接口,它是一个抽象类,定义了get方法;KubernetesClientServicesListSupplier继承了KubernetesServicesListSupplier,其构造器依赖KubernetesServiceInstanceMapper、KubernetesDiscoveryProperties、CoreV1Api、KubernetesNamespaceProvider;其get方法使用coreV1Api.listServiceForAllNamespaces或者coreV1Api.listNamespacedService来返回指定serviceId的V1Service信息,之后通过mapper转换为ServiceInstance。
整体来看spring-cloud-kubernetes-client-loadbalancer目前仅支持spring.cloud.kubernetes.loadbalancer.mode为SERVICE的模式,其实内部还是走的k8s的service的域名解析及负载均衡,无法细粒度到个性化的负载均衡。