247 lines
9.2 KiB
Markdown
247 lines
9.2 KiB
Markdown
# client-go示例
|
||
|
||
访问kubernetes集群有几下几种方式：
|
||
|
||
| 方式 | 特点 | 支持者 |
|
||
| ---------------------------------------- | ---------------------------------------- | ------ |
|
||
| Kubernetes dashboard | 直接通过Web UI进行操作，简单直接，可定制化程度低 | 官方支持 |
|
||
| kubectl | 命令行操作，功能最全，但是比较复杂，适合对其进行进一步的分装，定制功能，版本适配最好 | 官方支持 |
|
||
| [client-go](https://github.com/kubernetes/client-go) | 从kubernetes的代码中抽离出来的客户端包，简单易用，但需要小心区分kubernetes的API版本 | 官方支持 |
|
||
| [client-python](https://github.com/kubernetes-incubator/client-python) | python客户端，kubernetes-incubator | 官方支持 |
|
||
| [Java client](https://github.com/fabric8io/kubernetes-client) | fabric8中的一部分，kubernetes的java客户端 | redhat |
|
||
|
||
下面，我们基于[client-go](https://github.com/kubernetes/client-go)，对Deployment升级镜像的步骤进行了定制，通过命令行传递一个Deployment的名字、应用容器名和新image名字的方式来升级。代码和使用方式见 https://github.com/rootsongjc/kubernetes-client-go-sample 。
|
||
|
||
## kubernetes-client-go-sample
|
||
|
||
代码如下：
|
||
|
||
```go
|
||
package main
|
||
|
||
import (
|
||
"flag"
|
||
"fmt"
|
||
"os"
|
||
"path/filepath"
|
||
|
||
"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"
|
||
)
|
||
|
||
func main() {
|
||
var kubeconfig *string
|
||
if home := homeDir(); home != "" {
|
||
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
|
||
} else {
|
||
kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
|
||
}
|
||
deploymentName := flag.String("deployment", "", "deployment name")
|
||
imageName := flag.String("image", "", "new image name")
|
||
appName := flag.String("app", "app", "application name")
|
||
|
||
flag.Parse()
|
||
if *deploymentName == "" {
|
||
fmt.Println("You must specify the deployment name.")
|
||
os.Exit(0)
|
||
}
|
||
if *imageName == "" {
|
||
fmt.Println("You must specify the new image name.")
|
||
os.Exit(0)
|
||
}
|
||
// use the current context in kubeconfig
|
||
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
|
||
if err != nil {
|
||
panic(err.Error())
|
||
}
|
||
|
||
// create the clientset
|
||
clientset, err := kubernetes.NewForConfig(config)
|
||
if err != nil {
|
||
panic(err.Error())
|
||
}
|
||
deployment, err := clientset.AppsV1beta1().Deployments("default").Get(*deploymentName, metav1.GetOptions{})
|
||
if err != nil {
|
||
panic(err.Error())
|
||
}
|
||
if errors.IsNotFound(err) {
|
||
fmt.Printf("Deployment not found\n")
|
||
} else if statusError, isStatus := err.(*errors.StatusError); isStatus {
|
||
fmt.Printf("Error getting deployment%v\n", statusError.ErrStatus.Message)
|
||
} else if err != nil {
|
||
panic(err.Error())
|
||
} else {
|
||
fmt.Printf("Found deployment\n")
|
||
name := deployment.GetName()
|
||
fmt.Println("name ->", name)
|
||
containers := &deployment.Spec.Template.Spec.Containers
|
||
found := false
|
||
for i := range *containers {
|
||
c := *containers
|
||
if c[i].Name == *appName {
|
||
found = true
|
||
fmt.Println("Old image ->", c[i].Image)
|
||
fmt.Println("New image ->", *imageName)
|
||
c[i].Image = *imageName
|
||
}
|
||
}
|
||
if found == false {
|
||
fmt.Println("The application container not exist in the deployment pods.")
|
||
os.Exit(0)
|
||
}
|
||
_, err := clientset.AppsV1beta1().Deployments("default").Update(deployment)
|
||
if err != nil {
|
||
panic(err.Error())
|
||
}
|
||
}
|
||
}
|
||
|
||
func homeDir() string {
|
||
if h := os.Getenv("HOME"); h != "" {
|
||
return h
|
||
}
|
||
return os.Getenv("USERPROFILE") // windows
|
||
}
|
||
```
|
||
|
||
我们使用`kubeconfig`文件认证连接kubernetes集群，该文件默认的位置是`$HOME/.kube/config`。
|
||
|
||
该代码编译后可以直接在kubernetes集群之外，任何一个可以连接到API server的机器上运行。
|
||
|
||
**编译运行**
|
||
|
||
```bash
|
||
$ go get github.com/rootsongjc/kubernetes-client-go-sample
|
||
$ cd $GOPATH/src/github.com/rootsongjc/kubernetes-client-go-sample
|
||
$ make
|
||
$ ./update-deployment-image -h
|
||
Usage of ./update-deployment-image:
|
||
-alsologtostderr
|
||
log to standard error as well as files
|
||
-app string
|
||
application name (default "app")
|
||
-deployment string
|
||
deployment name
|
||
-image string
|
||
new image name
|
||
-kubeconfig string
|
||
(optional) absolute path to the kubeconfig file (default "/Users/jimmy/.kube/config")
|
||
-log_backtrace_at value
|
||
when logging hits line file:N, emit a stack trace
|
||
-log_dir string
|
||
If non-empty, write log files in this directory
|
||
-logtostderr
|
||
log to standard error instead of files
|
||
-stderrthreshold value
|
||
logs at or above this threshold go to stderr
|
||
-v value
|
||
log level for V logs
|
||
-vmodule value
|
||
comma-separated list of pattern=N settings for file-filtered logging
|
||
```
|
||
|
||
**使用不存在的image更新**
|
||
|
||
```bash
|
||
$ ./update-deployment-image -deployment filebeat-test -image harbor-001.jimmysong.io/library/analytics-docker-test:Build_9
|
||
Found deployment
|
||
name -> filebeat-test
|
||
Old image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_8
|
||
New image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_9
|
||
```
|
||
|
||
查看Deployment的event。
|
||
|
||
```bash
|
||
$ kubectl describe deployment filebeat-test
|
||
Name: filebeat-test
|
||
Namespace: default
|
||
CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800
|
||
Labels: k8s-app=filebeat-test
|
||
Selector: k8s-app=filebeat-test
|
||
Replicas: 2 updated | 3 total | 2 available | 2 unavailable
|
||
StrategyType: RollingUpdate
|
||
MinReadySeconds: 0
|
||
RollingUpdateStrategy: 1 max unavailable, 1 max surge
|
||
Conditions:
|
||
Type Status Reason
|
||
---- ------ ------
|
||
Available True MinimumReplicasAvailable
|
||
Progressing True ReplicaSetUpdated
|
||
OldReplicaSets: filebeat-test-2365467882 (2/2 replicas created)
|
||
NewReplicaSet: filebeat-test-2470325483 (2/2 replicas created)
|
||
Events:
|
||
FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage
|
||
--------- -------- ----- ---- ------------- -------- ------------
|
||
2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2
|
||
1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1
|
||
1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 2
|
||
```
|
||
|
||
可以看到老的ReplicaSet从3个replica减少到了2个，有2个使用新配置的replica不可用，目前可用的replica是2个。
|
||
|
||
这是因为我们指定的镜像不存在，查看Deployment的pod的状态。
|
||
|
||
```bash
|
||
$ kubectl get pods -l k8s-app=filebeat-test
|
||
NAME READY STATUS RESTARTS AGE
|
||
filebeat-test-2365467882-4zwx8 2/2 Running 0 33d
|
||
filebeat-test-2365467882-rqskl 2/2 Running 0 33d
|
||
filebeat-test-2470325483-6vjbw 1/2 ImagePullBackOff 0 4m
|
||
filebeat-test-2470325483-gc14k 1/2 ImagePullBackOff 0 4m
|
||
```
|
||
|
||
我们可以看到有两个pod正在拉取image。
|
||
|
||
**还原为原先的镜像**
|
||
|
||
将image设置为原来的镜像。
|
||
|
||
```bash
|
||
$ ./update-deployment-image -deployment filebeat-test -image harbor-001.jimmysong.io/library/analytics-docker-test:Build_8
|
||
Found deployment
|
||
name -> filebeat-test
|
||
Old image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_9
|
||
New image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_8
|
||
```
|
||
|
||
现在再查看Deployment的状态。
|
||
|
||
```bash
|
||
$ kubectl describe deployment filebeat-test
|
||
Name: filebeat-test
|
||
Namespace: default
|
||
CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800
|
||
Labels: k8s-app=filebeat-test
|
||
Selector: k8s-app=filebeat-test
|
||
Replicas: 3 updated | 3 total | 3 available | 0 unavailable
|
||
StrategyType: RollingUpdate
|
||
MinReadySeconds: 0
|
||
RollingUpdateStrategy: 1 max unavailable, 1 max surge
|
||
Conditions:
|
||
Type Status Reason
|
||
---- ------ ------
|
||
Available True MinimumReplicasAvailable
|
||
Progressing True NewReplicaSetAvailable
|
||
OldReplicaSets: <none>
|
||
NewReplicaSet: filebeat-test-2365467882 (3/3 replicas created)
|
||
Events:
|
||
FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage
|
||
--------- -------- ----- ---- ------------- -------- ------------
|
||
2h 8m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2
|
||
8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1
|
||
8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 2
|
||
2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2365467882 to 3
|
||
1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2470325483 to 0
|
||
```
|
||
|
||
可以看到available的replica个数恢复成3了。
|
||
|
||
其实在使用该命令的过程中，通过kubernetes dashboard的页面上查看Deployment的状态更直观，更加方便故障排查。
|
||
|
||
|
||
|
||
这也是dashboard最大的优势，简单、直接、高效。
|