通过命令学习k8s

1、kubectl 命令可以列出所有命令

2、kubectl version 命令可以查看版本号

3、kubectl cluster-info命令可以查看集群信息 （192.168.218.136:6443 即为kube-apiserver的IP和端口。）

[root@k8s-master ~]# kubectl cluster-info

Kubernetes master is running at https://192.168.218.136:6443

KubeDNS is running at https://192.168.218.136:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

4、也可以通过用户主目录下的.kube/config文件查看集群信息

用户主目录下的.kube/config

[root@k8s-master ~]# cat .kube/config

apiVersion: v1

clusters:

cluster:

certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FUR...0VSVElGSUNBVEUtLS0tLQo=

server: https://192.168.218.136:6443

contexts:

context:

cluster: kubernetes

user: kubernetes-admin

current-context: kubernetes-admin@kubernetes

kind: Config

preferences: {}

users:

name: kubernetes-admin

user:

client-certificate-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1J....BVEUtLS0tLQo=

client-key-data: LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS...QVRFIEtFWS0tLS0tCg==

5、还可以通过config view命令查看配置

[root@k8s-master ~]# kubectl config view

apiVersion: v1

clusters:

cluster:

certificate-authority-data: DATA+OMITTED

server: https://192.168.218.136:6443

contexts:

context:

cluster: kubernetes

user: kubernetes-admin

current-context: kubernetes-admin@kubernetes

kind: Config

preferences: {}

users:

name: kubernetes-admin

user:

client-certificate-data: REDACTED

client-key-data: REDACTED

---然后可以通过curl访问 api server api接口。也可以使用 10中的proxy访问api接口。
curl -k https://192.168.218.136:6443 --cert /etc/kubernetes/pki/apiserver-kubelet-client.crt --key /etc/kubernetes/pki/apiserver-kubelet-client.key

6、通过kubectl get node 查看节点信息
7、可通过kubectl get ns 拆开所有命名空间
8、通过kubectl get pod -A 查看所有命名空间下的pod
9、通过kubectl get svc-A 查看所有命名空间下的svc
10、kubectl proxy 命令开启代理

[root@k8s-master ~]# kubectl proxy --port=8080

Starting to serve on 127.0.0.1:8080
11、通过proxy http接口访问k8s

[root@k8s-master ~]# curl 127.0.0.1:8080

{

"paths": [

"/api",

"/api/v1",

"/apis",

"/apis/",

"/apis/apps",

"/apis/apps/v1",

"/apis/autoscaling",

"/apis/autoscaling/v1",

"/apis/autoscaling/v2beta1",

"/apis/autoscaling/v2beta2",

"/apis/batch",

"/apis/batch/v1",

"/apis/extensions",

"/apis/extensions/v1beta1",

"/apis/networking.k8s.io",

"/apis/networking.k8s.io/v1",

"/apis/networking.k8s.io/v1beta1",

"/apis/node.k8s.io",

"/apis/node.k8s.io/v1beta1",

"/apis/policy",

"/apis/policy/v1beta1",

"/healthz",

"/healthz/autoregister-completion",

"/healthz/etcd",

"/healthz/log",

"/healthz/ping",

"/livez",

"/livez/autoregister-completion",

"/livez/etcd",

"/livez/log",

"/livez/ping",

"/logs",

"/metrics",

"/openapi/v2",

"/readyz",

"/readyz/autoregister-completion",

"/readyz/etcd",

"/readyz/log",

"/readyz/ping",

"/readyz/shutdown",

"/version"

......

[root@k8s-master ~]# curl 127.0.0.1:8080/livez/ping

[root@k8s-master ~]# curl 127.0.0.1:8080/version

{

"major": "1",

"minor": "18",

"gitVersion": "v1.18.0",

"gitCommit": "9e991415386e4cf155a24b1da15becaa390438d8",

"gitTreeState": "clean",

"buildDate": "2020-03-25T14:50:46Z",

"goVersion": "go1.13.8",

"compiler": "gc",

"platform": "linux/amd64"

}

[root@k8s-master ~]# curl 127.0.0.1:8080/healthz

[root@k8s-master ~]# curl 127.0.0.1:8080/healthz/etcd

[root@k8s-master ~]# curl 127.0.0.1:8080/healthz/log

[root@k8s-master ~]# curl 127.0.0.1:8080/api

{

"kind": "APIVersions",

"versions": [

"v1"

"serverAddressByClientCIDRs": [

{

"clientCIDR": "0.0.0.0/0",

"serverAddress": "192.168.218.136:6443"

}

]

}

[root@k8s-master ~]# curl 127.0.0.1:8080/api/v1

{

"kind": "APIResourceList",

"groupVersion": "v1",

"resources": [

{

"name": "bindings",

"singularName": "",

"namespaced": true,

"kind": "Binding",

"verbs": [

"create"

]

{

"name": "componentstatuses",

"singularName": "",

"namespaced": false,

"kind": "ComponentStatus",

"verbs": [

"get",

"list"

"shortNames": [

"cs"

]

curl 127.0.0.1:8080/api/v1/pods --查看所有pods
curl 127.0.0.1:8080/api/v1/namespaces/kube-system/pods/kube-scheduler-k8s-master --查看某个命名空间下的某个pod

20、kubelet，kube-scheduler-k8s-master、kube-controller-manager-k8s-master、kube-proxy-s8v4t 是如何找到知道kubeapiserver的接口地址的呢？

他们都挂载了自己的配置文件，在 /etc/kubernetes/ 目录下。

其中 admin.conf 会被拷贝到用户家目录下的 .kube/config 文件中。

即cp /etc/kubernetes/admin.conf ~/.kube/config

[root@k8s-master ~]# ll /etc/kubernetes/

-rw------- 1 root root 5451 7月 28 19:38 admin.conf

-rw------- 1 root root 5491 7月 28 19:38 controller-manager.conf

-rw------- 1 root root 1879 7月 28 19:38 kubelet.conf

drwxr-xr-x 2 root root 113 7月 28 19:38 manifests

drwxr-xr-x 3 root root 4096 7月 28 19:38 pki

-rw------- 1 root root 5439 7月 28 19:38 scheduler.conf

另外，证书文件都放在pki目录下。

21、kubeapiserver 也可以开启http端口，这样就不需要证书了。
22、查看日志

kubectl logs kube-scheduler-k8s-master -n kube-system

kubectl logskube-scheduler-k8s-master -c kube-scheduler -n kube-system

22、proxy的代理功能

curl http://ip:8080/api/v1/proxy/namespace/{namespace}/services/{name} 相当于访问services 的url

curl http://ip:8080/api/v1/proxy/namespace/{namespace}/pods/{name} 相当于访问pod的url

23、访问etcd数据库

登录到k8s的etcd容器中，设置下面的环境变量

export ETCDCTL_ENDPOINTS=https://127.0.0.1:2379

export ETCDCTL_CACERT=/etc/kubernetes/pki/etcd/ca.crt

export ETCDCTL_CERT=/etc/kubernetes/pki/etcd/healthcheck-client.crt

export ETCDCTL_KEY=/etc/kubernetes/pki/etcd/healthcheck-client.key

export ETCDCTL_API=3

然后就可以通过etcdctl命令访问etcd数据库了

etcdctl get /gaofeng/name

etcdctl put /gaofeng/name gg

etcdctl get --prefix --keys-only /

etcdctl get /registry/services/specs/default/kubernetes