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使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

时间：2021-09-16 00:52     来源/作者：运维董伟振

说明

可以调取k8s api 接口的工具有很多，这里我就介绍下client-go

gitlab上client-go项目地址: https://github.com/kubernetes/client-go  

这个工具是由kubernetes官方指定维护的，大家可以放心使用

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

效果

运行完成后，可以直接获取k8s集群信息等

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

实现

1、拉取工具源码

注意事项：https://github.com/kubernetes/client-go/blob/master/install.md

总结：一定要拉取跟集群对应版本的工具源码，比如我这里集群是1.17版本，那我就拉取17版本

go get k8s.io/client-go@v0.17.0

我是1.17版本的集群，所有依赖文件放在这了，可以直接使用client-go k8s1.17 api

2、创建目录结构

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

集群的角色配置文件（默认在/root/.kube/config）
kube/config

查询代码实例

查询pod信息

查看ferry命名空间下pod的信息，pod名字、pod的ip

vim kube-api.go

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package main
 
import (
    "fmt"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
    "k8s.io/client-go/kubernetes"
 
    "k8s.io/client-go/tools/clientcmd"
)
 
func main() {
 
    config, err := clientcmd.buildconfigfromflags("", "kube/config")
    if err != nil {
        panic(err)
    }
    client, _ := kubernetes.newforconfig(config)
    pods ,err := client.corev1().pods("ferry").list(metav1.listoptions{})
    if err != nil {
        fmt.println(err)
        return
    }
 
    for _,v := range  pods.items {
        fmt.printf(" 命名空间是：%v\n pod名字：%v\n ip：%v\n\n",v.namespace,v.name,v.status.podip)
    }
}

自动关联依赖

go mod tidy

运行结果

$ go run kube-api.go

 命名空间是：ferry
 pod名字：ferry-backend-7949596679-h8lxb
 ip：10.42.1.14

 命名空间是：ferry
 pod名字：ferry-mysql-8db8d49f7-6psbv
 ip：10.42.1.11

查询一个pod是否在一个命名空间下

https://github.com/kubernetes/client-go/blob/master/examples/in-cluster-client-configuration/main.go
每3秒检查下nginx-74959fc858-cp48w是否在default命名空间下

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package main
 
import (
    "context"
    "fmt"
    "k8s.io/apimachinery/pkg/api/errors"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "time"
)
 
func main() {
 
    config, err := clientcmd.buildconfigfromflags("", "kube/config")
    if err != nil {
        panic(err)
    }
    clientset, err := kubernetes.newforconfig(config)
    if err != nil {
        panic(err.error())
    }
    for {
        // get pods in all the namespaces by omitting namespace
        // or specify namespace to get pods in particular namespace
        pods, err := clientset.corev1().pods("").list(context.todo(), metav1.listoptions{})
        if err != nil {
            panic(err.error())
        }
        fmt.printf("there are %d pods in the cluster\n", len(pods.items))
 
        // examples for error handling:
        // - use helper functions e.g. errors.isnotfound()
        // - and/or cast to statuserror and use its properties like e.g. errstatus.message
        _, err = clientset.corev1().pods("default").get(context.todo(), "nginx-74959fc858-cp48w", metav1.getoptions{})
        if errors.isnotfound(err) {
            fmt.printf("pod nginx-74959fc858-cp48w not found in default namespace\n")
        } else if statuserror, isstatus := err.(*errors.statuserror); isstatus {
            fmt.printf("error getting pod %v\n", statuserror.errstatus.message)
        } else if err != nil {
            panic(err.error())
        } else {
            fmt.printf("found nginx-74959fc858-cp48w pod in default namespace\n")
        }
 
     time.sleep(3 * time.second)
    }
}

运行结果

$ go run kube-api.go
there are 22 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 22 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 22 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 23 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 22 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 22 pods in the cluster
found nginx-74959fc858-cp48w pod in default namespace
there are 21 pods in the cluster
\\在集群种手动删除了这个pod
pod nginx-74959fc858-cp48w not found in default namespace
there are 21 pods in the cluster
pod nginx-74959fc858-cp48w not found in default namespace

查询deployment服务类型信息

查询default命名空间下的deployment服务信息，服务名字、服务副本数

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package main
 
import (
    "fmt"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
    "k8s.io/client-go/kubernetes"
 
    "k8s.io/client-go/tools/clientcmd"
)
 
func main() {
 
    config, err := clientcmd.buildconfigfromflags("", "kube/config")
    if err != nil {
        panic(err)
    }
    client, _ := kubernetes.newforconfig(config)
    deploymentlist, err := client.appsv1().deployments("default").list(metav1.listoptions{})
    if err != nil {
        fmt.println(err)
        return
    }
 
    for _,v := range deploymentlist.items {
        fmt.printf(" 命名空间是：%v\n deployment服务名字：%v\n 副本个数：%v\n\n",v.namespace,v.name,v.status.replicas)
    }
 
}

运行结果

$ go run kube-api.go
 命名空间是：default
 deployment服务名字：nginx
 副本个数：2

创建deployment资源

https://github.com/kubernetes/client-go/blob/master/examples/create-update-delete-deployment/main.go

复制一个config文件到当前目录下

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

创建一个deployment类型的nginx服务

vim deployment-create.go

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package main
 
import (
    "context"
    "flag"
    "fmt"
 
    "path/filepath"
 
    appsv1 "k8s.io/api/apps/v1"
    apiv1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/util/homedir"
    //
    // uncomment to load all auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth"
    //
    // or uncomment to load specific auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth/azure"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/openstack"
)
 
func main() {
    var kubeconfig *string
    if home := homedir.homedir(); home != "" {
        kubeconfig = flag.string("kubeconfig", filepath.join("config"), "(optional) absolute path to the kubeconfig file")
    } else {
        kubeconfig = flag.string("kubeconfig", "", "absolute path to the kubeconfig file")
    }
    flag.parse()
 
    config, err := clientcmd.buildconfigfromflags("", *kubeconfig)
    if err != nil {
        panic(err)
    }
    clientset, err := kubernetes.newforconfig(config)
    if err != nil {
        panic(err)
    }
 
    deploymentsclient := clientset.appsv1().deployments(apiv1.namespacedefault)
 
    deployment := &appsv1.deployment{
        objectmeta: metav1.objectmeta{
            name: "nginx-deployment",
        },
        spec: appsv1.deploymentspec{
            replicas: int32ptr(2),
            selector: &metav1.labelselector{
                matchlabels: map[string]string{
                    "app": "nginx",
                },
            },
            template: apiv1.podtemplatespec{
                objectmeta: metav1.objectmeta{
                    labels: map[string]string{
                        "app": "nginx",
                    },
                },
                spec: apiv1.podspec{
                    containers: []apiv1.container{
                        {
                            name:  "web",
                            image: "nginx:1.12",
                            ports: []apiv1.containerport{
                                {
                                    name:          "http",
                                    protocol:      apiv1.protocoltcp,
                                    containerport: 80,
                                },
                            },
                        },
                    },
                },
            },
        },
    }
 
    // create deployment
    fmt.println("creating deployment nginx...")
    result, err := deploymentsclient.create(context.todo(), deployment, metav1.createoptions{})
    if err != nil {
        panic(err)
    }
    fmt.printf("created deployment %q.\n", result.getobjectmeta().getname())
 
}

运行结果

$ go run deployment-create.go
creating deployment nginx...
created deployment "nginx-deployment".

更新deployment类型服务

https://github.com/kubernetes/client-go/blob/master/examples/create-update-delete-deployment/main.go
更改服务的副本数，由上一步创建的2修改成1，并修改镜像由nginx1.12–>nginx1.13

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package main
 
import (
    "context"
    "flag"
    "fmt"
    "path/filepath"
 
    apiv1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/util/homedir"
    "k8s.io/client-go/util/retry"
    //
    // uncomment to load all auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth"
    //
    // or uncomment to load specific auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth/azure"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/openstack"
)
 
func main() {
    var kubeconfig *string
    if home := homedir.homedir(); home != "" {
        kubeconfig = flag.string("kubeconfig", filepath.join("config"), "(optional) absolute path to the kubeconfig file")
    } else {
        kubeconfig = flag.string("kubeconfig", "", "absolute path to the kubeconfig file")
    }
    flag.parse()
 
    config, err := clientcmd.buildconfigfromflags("", *kubeconfig)
    if err != nil {
        panic(err)
    }
    clientset, err := kubernetes.newforconfig(config)
    if err != nil {
        panic(err)
    }
 
    deploymentsclient := clientset.appsv1().deployments(apiv1.namespacedefault)
 
    retryerr := retry.retryonconflict(retry.defaultretry, func() error {
        // retrieve the latest version of deployment before attempting update
        // retryonconflict uses exponential backoff to avoid exhausting the apiserver
        result, geterr := deploymentsclient.get(context.todo(), "nginx-deployment", metav1.getoptions{})
        if geterr != nil {
            panic(fmt.errorf("failed to get latest version of deployment: %v", geterr))
        }
 
        result.spec.replicas = int32ptr(1)                           // reduce replica count
        result.spec.template.spec.containers[0].image = "nginx:1.13" // change nginx version
        _, updateerr := deploymentsclient.update(context.todo(), result, metav1.updateoptions{})
        return updateerr
    })
    if retryerr != nil {
        panic(fmt.errorf("update failed: %v", retryerr))
    }
    fmt.println("updated deployment nginx")
 
}
func int32ptr(i int32) *int32 { return &i }

运行结果

$ go run deployment-update.go
updated deployment nginx

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

删除deployment类型服务

删除上面创建的nginx-deployment资源，删除之前添加了确认语句

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package main
 
import (
    "bufio"
    "context"
    "flag"
    "fmt"
    "os"
    "path/filepath"
 
    apiv1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/util/homedir"
    //
    // uncomment to load all auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth"
    //
    // or uncomment to load specific auth plugins
    // _ "k8s.io/client-go/plugin/pkg/client/auth/azure"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
    // _ "k8s.io/client-go/plugin/pkg/client/auth/openstack"
)
 
func main() {
    var kubeconfig *string
    if home := homedir.homedir(); home != "" {
        kubeconfig = flag.string("kubeconfig", filepath.join( "config"), "(optional) absolute path to the kubeconfig file")
    } else {
        kubeconfig = flag.string("kubeconfig", "", "absolute path to the kubeconfig file")
    }
    flag.parse()
 
    config, err := clientcmd.buildconfigfromflags("", *kubeconfig)
    if err != nil {
        panic(err)
    }
    clientset, err := kubernetes.newforconfig(config)
    if err != nil {
        panic(err)
    }
 
    deploymentsclient := clientset.appsv1().deployments(apiv1.namespacedefault)
 
     prompt()
    fmt.println("deleting deployment nginx...")
    deletepolicy := metav1.deletepropagationforeground
    if err := deploymentsclient.delete(context.todo(), "nginx-deployment", metav1.deleteoptions{
        propagationpolicy: &deletepolicy,
    }); err != nil {
        panic(err)
    }
    fmt.println("deleted deployment.")
}
 
func prompt() {
    fmt.printf("-> press return key to continue, will delete!")
    scanner := bufio.newscanner(os.stdin)
    for scanner.scan() {
        break
    }
    if err := scanner.err(); err != nil {
        panic(err)
    }
    fmt.println()
}
 
func int32ptr(i int32) *int32 { return &i }

运行结果

$ go run deployment-delete.go
-> press return key to continue, will delete! 这里点击回车后继续删除资源

deleting deployment nginx...
deleted deployment.

使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)

到此这篇关于使用client-go工具调kubernetes api接口(v1.17版本)的文章就介绍到这了,更多相关client-go调用kubernetes api内容请搜索服务器之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持服务器之家！

原文链接：https://blog.csdn.net/zhanremo3062/article/details/119888687

标签：
API Kubernetes client-go 

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