kubernetes 客户端KubeClient使用及经常使用api

KubeClient是kubernetes 的C#语言客户端简单易用，KubeClient是.NET Core（目标netstandard1.4）的可扩展Kubernetes API客户端， github地址： https://github.com/tintoy/dotnet-kube-client/，还有一个官方的SDK https://github.com/kubernetes-client/csharp/  ，这两个sdk的设计哲学上是不同的， 官方的客户端使用代码生成，代码生成的使用是有限的; 生成的客户端倾向于非惯用，而且对于像Kubernetes那样大的Swagger规范，最终会在客户端类上直接放置太多方法。KubeClient的方法是生成模型类并手动编写实际操做方法，以提供改进的开发使用体验（即有用且一致的异常类型）。

Kubernetes API中的某些操做能够根据传入的参数返回不一样的响应。例如，删除a的请求若是调用者指定则v1/Pod返回现有v1/Pod（做为PodV1模型）DeletePropagationPolicy.Foreground可是若是任何其余类型则返回v1/Status（做为StatusV1模型）的DeletePropagationPolicy指定。

为了处理这种类型的多态响应，KubeClient使用KubeResultV1模型（及其派生的实现，KubeResourceResultV1<TResource>和KubeResourceListResultV1<TResource>）。

KubeResourceResultV1<TResource>能够隐式地转换为a TResource或a StatusV1，所以消费代码能够继续使用客户端，就好像它指望操做只返回资源或指望它只返回StatusV1：

PodV1 existingPod = await client.PodsV1().Delete("mypod", propagationPolicy: DeletePropagationPolicy.Foreground);

// OR: StatusV1 deleteStatus = await client.PodsV1().Delete("mypod", propagationPolicy: DeletePropagationPolicy.Background);

KubeClient设计也易于扩展。它的 KubeApiClient提供了Kubernetes API的顶级入口点，扩展方法用于公开更具体的资源客户端。Ocelot的kubernetes 集成模块就是使用KubeClient ，具体代码参见https://github.com/ThreeMammals/Ocelot/tree/develop/src/Ocelot.Provider.Kubernetes，这个模块是咱们已经在生产环境下使用过了，最近合并进入Ocelot的主干代码，文档参见：https://ocelot.readthedocs.io/en/latest/features/kubernetes.html

简单代码示例参见

using KubeClient;
using KubeClient.Models;
using Ocelot.Logging;
using Ocelot.ServiceDiscovery.Providers;
using Ocelot.Values;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Ocelot.Provider.Kubernetes
{
     public class Kube : IServiceDiscoveryProvider
     {
         private KubeRegistryConfiguration kubeRegistryConfiguration;
         private IOcelotLogger logger;
         private IKubeApiClient kubeApi;

 

        public Kube(KubeRegistryConfiguration kubeRegistryConfiguration, IOcelotLoggerFactory factory, IKubeApiClientFactory kubeClientFactory)
         {
             this.kubeRegistryConfiguration = kubeRegistryConfiguration;
             this.logger = factory.CreateLogger<Kube>();
             this.kubeApi = kubeClientFactory.Get(kubeRegistryConfiguration);
         }

 

        public async Task<List<Service>> Get()
         {
             var service = await kubeApi.ServicesV1()
                 .Get(kubeRegistryConfiguration.KeyOfServiceInK8s, kubeRegistryConfiguration.KubeNamespace);
             var services = new List<Service>();
             if (IsValid(service))
             {
                 services.Add(BuildService(service));
             }
             else
             {
                 logger.LogWarning($"namespace:{kubeRegistryConfiguration.KubeNamespace }service:{kubeRegistryConfiguration.KeyOfServiceInK8s} Unable to use ,it is invalid. Address must contain host only e.g. localhost and port must be greater than 0");
             }
             return services;
         }

 

        private bool IsValid(ServiceV1 service)
         {
             if (string.IsNullOrEmpty(service.Spec.ClusterIP) || service.Spec.Ports.Count <= 0)
             {
                 return false;
             }

            return true;
         }

 

        private Service BuildService(ServiceV1 serviceEntry)
         {
             var servicePort = serviceEntry.Spec.Ports.FirstOrDefault();
             return new Service(
                 serviceEntry.Metadata.Name,
                 new ServiceHostAndPort(serviceEntry.Spec.ClusterIP, servicePort.Port),
                 serviceEntry.Metadata.Uid,
                 string.Empty,
                 Enumerable.Empty<string>());
         }
     }
}

经常使用api

1.deployment

https://github.com/tintoy/dotnet-kube-client/blob/develop/samples/DeploymentWithRollback/Program.cs

2.service

参看上面ocelot 的代码

3.pod

https://github.com/tintoy/dotnet-kube-client/blob/develop/samples/noob-exec/Program.cs

总结

通常操做kubernetes ，二次开发的时候只须要对deployment、service作相关工做。操做起来仍是比较简便的。