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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定義了ServiceInstanceListSupplier，它繼承自Supplier，其泛型為Flux<List<ServiceInstance>>，它定義了getServiceId、get(Request)方法，並提供了builder靜態方法Request
org/springframework/cloud/client/loadbalancer/Request.java
public interface Request<C> {
// Avoid breaking backward compatibility
default C getContext() {
return null;
}
// TODO: define contents
}Request提供了getContext方法，預設返回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;
}
@Override
public T getContext() {
return context;
}
public void setContext(T context) {
this.context = context;
}
@Override
public String toString() {
ToStringCreator to = new ToStringCreator(this);
to.append("context", context);
return to.toString();
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof DefaultRequest<?> that)) {
return false;
}
return Objects.equals(context, that.context);
}
@Override
public int hashCode() {
return Objects.hash(context);
}
}DefaultRequest實現了Request，其定義的泛型為context的型別
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;
}
@Override
public String getServiceId() {
return environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
}
@Override
public abstract Flux<List<ServiceInstance>> get();
}KubernetesServicesListSupplier宣告實現ServiceInstanceListSupplier介面，它是一個抽象類，定義了get方法，這裡忽略了get(Request)，沒有將Request傳遞下來
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();
}
@Override
public 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繼承了KubernetesServicesListSupplier，其構造器依賴KubernetesServiceInstanceMapper、KubernetesDiscoveryProperties、CoreV1Api、KubernetesNamespaceProvider；其get方法使用coreV1Api.listServiceForAllNamespaces或者coreV1Api.listNamespacedService來返回指定serviceId的V1Service資訊，之後透過mapper轉換為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定義了apiVersion、kind、metadata、spec、status屬性
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介面定義了map方法，它提供了createHost、isSecure、getMapWithPrefixedKeys靜態方法
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;
}
@Override
public 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實現了KubernetesServiceInstanceMapper介面，其泛型為V1Service，其map方法先透過service.getSpec().getPorts()獲取port資訊，之後透過createHost返回svc的短域名<servicename>.<namespace>.svc.<clusterdomain>，例如service-a.default.svc.cluster.local，最後建立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設定為SERVICE的時候會自動建立kubernetesServicesListSupplier
小結
spring-cloud-loadbalancer定義了ServiceInstanceListSupplier，它繼承自Supplier，其泛型為Flux<List<ServiceInstance>>，它定義了getServiceId、get(Request)方法，並提供了builder靜態方法；KubernetesServicesListSupplier宣告實現ServiceInstanceListSupplier介面，它是一個抽象類，定義了get方法；KubernetesClientServicesListSupplier繼承了KubernetesServicesListSupplier，其構造器依賴KubernetesServiceInstanceMapper、KubernetesDiscoveryProperties、CoreV1Api、KubernetesNamespaceProvider；其get方法使用coreV1Api.listServiceForAllNamespaces或者coreV1Api.listNamespacedService來返回指定serviceId的V1Service資訊，之後透過mapper轉換為ServiceInstance。
整體來看spring-cloud-kubernetes-client-loadbalancer目前僅支援spring.cloud.kubernetes.loadbalancer.mode為SERVICE的模式，其實內部還是走的k8s的service的域名解析及負載均衡，無法細粒度到個性化的負載均衡。