kubernetes 客戶端KubeClient使用及經常使用api

KubeClient是kubernetes 的C#語言客戶端簡單易用，KubeClient是.NET Core（目標netstandard1.4）的可擴展Kubernetes API客戶端， github地址： https://github.com/tintoy/dotnet-kube-client/，還有一個官方的SDK https://github.com/kubernetes-client/csharp/  ，這兩個sdk的設計哲學上是不同的， 官方的客戶端使用代碼生成，代碼生成的使用是有限的; 生成的客戶端傾向於非慣用，而且對於像Kubernetes那樣大的Swagger規範，最終會在客戶端類上直接放置太多方法。KubeClient的方法是生成模型類並手動編寫實際操做方法，以提供改進的開發使用體驗（即有用且一致的異常類型）。

Kubernetes API中的某些操做能夠根據傳入的參數返回不一樣的響應。例如，刪除a的請求若是調用者指定則v1/Pod返回現有v1/Pod（做爲PodV1模型）DeletePropagationPolicy.Foreground可是若是任何其餘類型則返回v1/Status（做爲StatusV1模型）的DeletePropagationPolicy指定。

爲了處理這種類型的多態響應，KubeClient使用KubeResultV1模型（及其派生的實現，KubeResourceResultV1<TResource>和KubeResourceListResultV1<TResource>）。

KubeResourceResultV1<TResource>能夠隱式地轉換爲a TResource或a StatusV1，所以消費代碼能夠繼續使用客戶端，就好像它指望操做只返回資源或指望它只返回StatusV1：

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

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

KubeClient設計也易於擴展。它的 KubeApiClient提供了Kubernetes API的頂級入口點，擴展方法用於公開更具體的資源客戶端。Ocelot的kubernetes 集成模塊就是使用KubeClient ，具體代碼參見https://github.com/ThreeMammals/Ocelot/tree/develop/src/Ocelot.Provider.Kubernetes，這個模塊是咱們已經在生產環境下使用過了，最近合併進入Ocelot的主幹代碼，文檔參見：https://ocelot.readthedocs.io/en/latest/features/kubernetes.html

簡單代碼示例參見

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>());
         }
     }
}

經常使用api

1.deployment

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

2.service

參看上面ocelot 的代碼

3.pod

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

總結

通常操做kubernetes ，二次開發的時候只須要對deployment、service作相關工做。操做起來仍是比較簡便的。