java实现kubernates API的访问调用

1. 前言

kubernetes及各开源社区为开发人员提供了各种语言版的Client Library，让我们可以通过编程的方式可以实现调用Kubernetes API，从而完成pod、service、RC等资源的图形化创建和管理。本篇主要介绍使用java语言的实现

2. 使用场景

开发基于kubernetes的容器云管理平台

3. 基于的框架

用java语言开发的有两种，一个是基于Jersey的，一个是基于Fabric8。
-Jersey是一个方便简化开发RESRFul Web Service的框架，契合kubernetesAPI的设计，所以采用jersey会比较省力，但还是需要开发者自己做很多工作。
-Fabric8中的kubernates-client.xx.jar，kubernates-model.xx.jar等工具包包对kubernates api做了很好的封装，访问代码比较简单。
本篇将选择fabric8实现

4. 使用步骤

4.1 首先导入核心jar包

4.2 创建连接API-Server的client

package org.demo.framework.engine.k8s.util;

import io.fabric8.kubernetes.api.model.*;
import io.fabric8.kubernetes.api.model.extensions.*;
import io.fabric8.kubernetes.api.model.extensions.Deployment;
import io.fabric8.kubernetes.client.Config;
import io.fabric8.kubernetes.client.ConfigBuilder;
import io.fabric8.kubernetes.client.*;
import okhttp3.TlsVersion;
import org.apache.log4j.Logger;

import java.io.Closeable;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

public class Fabric8KubeUtils implements KubeUtils {
    private KubernetesClient client;
    private static final int CONNECTION_TIMEOUT = 3 * 1000;
    private static final int REQUEST_TIMEOUT = 3 * 1000;

    private static Logger logger = Logger.getLogger(Fabric8KubeUtils.class);


    @Override
    public KubernetesClient getClient() {
        return client;
    }

    @Override
    public void setClient(KubernetesClient client) {
        this.client = client;
    }


    private Fabric8KubeUtils(KubernetesClient client) {
        this.client = client;
    }


    /**传入参数，连接k8s的api server**/
    public static KubeUtils buildKubeUtils(Cluster cluster, String namespace) throws K8sDriverException {
        if (cluster == null) {
            throw new K8sDriverException("cluster is null");
        }
        String key = cluster.md5Key(namespace);
        if (KUBEUTILSMAP.containsKey(key)) {
            return KUBEUTILSMAP.get(key);
        }
        String master = cluster.getApi();
        master = CommonUtil.fullUrl(master);
        if (StringUtils.isBlank(master)) {
            throw new K8sDriverException("master api is null, cluster id=" + cluster.getId() + ", cluster name=" + cluster.getName());
        }

        Config config;
        if (master.toLowerCase().startsWith("https://")) {
            config = new ConfigBuilder().withMasterUrl(master)
                    .withTrustCerts(true)
                    .withNamespace(namespace)
                    .withOauthToken(cluster.getOauthToken())
                    .withUsername(cluster.getUsername())
                    .withPassword(cluster.getPassword())
                    .removeFromTlsVersions(TlsVersion.TLS_1_0)
                    .removeFromTlsVersions(TlsVersion.TLS_1_1)
                    .removeFromTlsVersions(TlsVersion.TLS_1_2)
                    .withRequestTimeout(REQUEST_TIMEOUT)
                    .withConnectionTimeout(CONNECTION_TIMEOUT)
                    .build();
        } else {
            config = new ConfigBuilder().withMasterUrl(master)
                    .withNamespace(namespace)
                    .withOauthToken(cluster.getOauthToken())
                    .withUsername(cluster.getUsername())
                    .withPassword(cluster.getPassword())
                    .removeFromTlsVersions(TlsVersion.TLS_1_0)
                    .removeFromTlsVersions(TlsVersion.TLS_1_1)
                    .removeFromTlsVersions(TlsVersion.TLS_1_2)
                    .withTrustCerts(true)
                    .withRequestTimeout(REQUEST_TIMEOUT)
                    .withConnectionTimeout(CONNECTION_TIMEOUT)
                    .build();
        }
        KubeUtils kubeUtils = buildKubeUtils(config);
        KUBEUTILSMAP.putIfAbsent(key, kubeUtils);
        return kubeUtils;
    }

    /**创建client**/
    public static KubeUtils buildKubeUtils(Config config) throws K8sDriverException {
        KubernetesClient client;
        try {
            client = new DefaultKubernetesClient(config);
        } catch (Exception e) {
            throw new K8sDriverException("instantialize kubernetes client error");
        }
        return new Fabric8KubeUtils(client);
    }


}

4.3 创建k8s的资源对象，作为参传给client操作k8s（增删改时需要）

// 可以通过k8s??Builder()来创建资源对象
// 如下创建一个service对象，lb为包含service必要信息的实体类对象
Service newService = new K8sServiceBuilder(lb).build();

4.4 通过得到的client，可以对k8s的各种资源增删改查各种操作：
Nodes
Namespaces
Services
Replicationcontrollers
Pods
Deployments
Resourcequotas

/**创建pod**/
@Override
    public Pod createPod(Pod pod)
            throws K8sDriverException {
        logger.debug("create pod with specify=" + pod.toString());
        try {
            return client.pods().create(pod);
        } catch (KubernetesClientException e) {
            throw new K8sDriverException(e.getMessage());
        }
    }

/**创建service**/
@Override
public Service createService(Service service)
            throws K8sDriverException {
    logger.debug("create service=" + service);
    if (service == null) {
         return null;
    }
    try {
         return client.services().create(service);
    } catch (KubernetesClientException e) {
        throw new K8sDriverException(e.getMessage());
    }
}

/**创建RC**/
 @Override
    public ReplicationController createReplicationController(ReplicationController rc)
            throws K8sDriverException {
        if (rc == null) {
            return null;
        }
        logger.debug("create replication controller with rc=\n" + rc);
        try {
            return client.replicationControllers().create(rc);
        } catch (KubernetesClientException e) {
            throw new K8sDriverException(e.getMessage());
        }

    }

/**创建deployment**/
@Override
    public Deployment createDeployment(Deployment deployment) throws K8sDriverException {
        if (deployment == null) {
            return null;
        }
        logger.debug("create deployment with deployment=\n" + deployment);
        try {
            return client.extensions().deployments().create(deployment);
        } catch (KubernetesClientException e) {
            throw new K8sDriverException(e.getMessage());
        }
    }


/**按条件列出所有node**/
@Override
    public NodeList listNode(Map labelSelector) throws K8sDriverException {
        logger.debug("list node with selector=" + labelSelector);
        try {
            return client.nodes().withLabels(labelSelector).list();
        } catch (KubernetesClientException e) {
            throw new K8sDriverException(e.getMessage());
        }
    }