k8s中文文档
- k8s概念比较多，有什么概念的疑惑的推 荐看k8s中文文档。
me的环境
- 操作系统：centos7
- docker：1.12.6
环境跟me的不一致？不要慌，基本大部分操作都是行的通的。
还慌？那就直接用网页在线版的kubernets吧
kubernets单机版安装部署
kubernetes部署算是有一定门槛的。为了不从入门到放弃，推荐一开始安装单机版作为入门熟悉kubectl指令、了解工作原理。
安装流程，切换成root
# 关闭centos自带的防火墙
$ sudo systemctl disable firewalld
$ sudo systemctl stop firewalld
# 安装etcd和kubernetes软件（会自动安装docker）
$ sudo yum install -y etcd kubernetes
修改两处配置
- Docker配置文件/etc/sysconfig/docker, OPTIONS=’–selinux-enabled=false –insecure-registry gcr.io’
# Modify these options if you want to change the way the docker daemon runs
OPTIONS='--selinux-enabled=false --insecure-registry gcr.io'
if [ -z "${DOCKER_CERT_PATH}" ]; then
DOCKER_CERT_PATH=/etc/docker
fi
# Do not add registries in this file anymore. Use /etc/containers/registries.conf
# from the atomic-registries package.
#
# docker-latest daemon can be used by starting the docker-latest unitfile.
# To use docker-latest client, uncomment below lines
#DOCKERBINARY=/usr/bin/docker-latest
#DOCKERDBINARY=/usr/bin/dockerd-latest
#DOCKER_CONTAINERD_BINARY=/usr/bin/docker-containerd-latest
#DOCKER_CONTAINERD_SHIM_BINARY=/usr/bin/docker-containerd-shim-latest
- Kubernetes apiservce配置文件/etc/kubernetes/apiserver,把–admission_control参数钟的ServiceAccount删除
###
# kubernetes system config
#
# The following values are used to configure the kube-apiserver
#
# The address on the local server to listen to.
KUBE_API_ADDRESS="--insecure-bind-address=0.0.0.0"
# The port on the local server to listen on.
# KUBE_API_PORT="--port=8080"
# Port minions listen on
# KUBELET_PORT="--kubelet-port=10250"
# Comma separated list of nodes in the etcd cluster
KUBE_ETCD_SERVERS="--etcd-servers=http://127.0.0.1:2379"
# Address range to use for services
KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"
# default admission control policies
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota"
# Add your own!
KUBE_API_ARGS=""
启动所有服务
# systemctl start etcd
# systemctl start docker
# systemctl start kube-apiserver
# systemctl start kube-controller-manager
# systemctl start kube-scheduler
# systemctl start kubelet
# systemctl start kube-proxy
初入门小实例
-
部署nginx服务
$ kubectl run my-nginx --image=nginx --port=80
$ kubectl get pod # 查看pod
发现pod状态无论多久都是处于pending。READY字段一直是0/1,服务部署失败的原因是”中国墙“的问题导致无法下载pod启动时需要的谷歌镜像，所以我们得间接的创建所需的镜像。
补充： Pending状态表示API Server已经创建Pod，但Pod内还有一个或者多个容器没有创建，或者正在下载镜像的过程。详细的参考
Pod声明周期和重启策略
-
创建gcr.io/google_containers/pause-amd64:3.0镜像
$ docker pull googlecontainer/pause-amd64:3.0
$ docker tag googlecontainer/pause-amd64:3.0 gcr.io/google_containers/pause-amd64:3.0
kubernets指令
- 实例流程
# 查看版本
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}
# 显示集群信息
$ kubectl cluster-info
Kubernetes master is running at http://localhost:8080
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
# 查看集群中有几个Node
$ kubectl get nodes
NAME STATUS AGE
127.0.0.1 Ready 18h
# 运行一个镜像
$ kubectl run my-nginx --image=nginx --replicas=2 --port=80
deployment "my-nginx" created
# 查看pod
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
my-nginx-379829228-cwlbb 0/1 ContainerCreating 0 20s
my-nginx-379829228-czk6w 1/1 Running 0 20s
# 查看服务详情信息
$ kubectl describe pod my-nginx-379829228-cwlbb
# 查看已部署
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-nginx 2 2 2 2 3m
# 删除pod
$ kubectl delete pod my-nginx-379829228-cwlbb
pod "my-nginx-379829228-cwlbb" deleted
# 再次查看pod，发现由于replicas机制，pod又生成一个新的
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
my-nginx-379829228-czk6w 1/1 Running 0 11m
my-nginx-379829228-gjd7d 0/1 ContainerCreating 0 5s
# 删除部署的my-nginx服务。彻底删除pod
$ kubectl delete deployment my-nginx
deployment "my-nginx" deleted
对比docker命令
k8s的学习路线基本都是从docker[容器]到k8s的，因此两个对比理解有助于记忆
# docker run
$ docker run -d -e DOMAIN=cluster --name my-nginx -p 80:80 nginx
$ kubectl run my-nginx --image=nginx --port=80 --env="DOMAIN=cluster"
# docker ps
$ docker ps
$ kubectl get pods
# docker exec
$ docker exec [容器id] ls
$ kubectl exec [pod_id] ls
# docker exec 交互式
$ docker exec -it [容器id] /bin/sh
$ kubectl exec -it [pod_id] -- /bin/sh
# docker info
$ docker info
$ kubectl cluster-info
重要名词
| 名词 | 翻译 |
|---|---|
| Namespace | 命名空间 |
| Endpoint | 服务端点 |
| Controller Manager | 管理控制中心 |
| Replication | 副本控制器 |
yaml文件管理服务
-
用yaml文件来创建服务
# vi nginx.yaml
piVersion: extensions/v1beta1
kind: Deployment
metadata:
name: my-nginx
spec:
replicas: 3
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
-
启动管理服务
# 根据yaml文件创建服务
$ kubectl create -f nginx.yaml
deployment "my-nginx" created
# 查看deployment
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-nginx 3 3 3 3 6s
# 查看Pod
$ kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-4087004473-dtrjp 1/1 Running 0 7s
my-nginx-4087004473-jz80p 1/1 Running 0 7s
my-nginx-4087004473-wh576 1/1 Running 0 7s
# 根据yaml文件删除服务
$ kubectl delete -f nginx.yaml
deployment "my-nginx" deleted
$ kubectl get pod
No resources found.
$ kubectl get deployment
No resources found.
Service
-
到此，我们部署一个nginx服务
$ kubectl run my-nginx --image=nginx --port=80
# 创建一个service 且将其暴露到集群外可供访问
$ kubectl expose deployment/my-nginx --type="NodePort" --port 80
service "my-nginx" exposed
# 此时service列表多个my-nginx服务
$ kubectl get services
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes 10.254.0.1
443/TCP 7d my-nginx 10.254.255.103
80:32589/TCP 7s
宿主主机内访问该服务
$ kubectl describe service/my-nginx
# 显示的字段有Endpoints: 172.17.0.2:80
$ curl 172.17.0.2.80
同网段的机器访问该服务
$ curl 192.168.33.101:32589
deployments
# 运行nginx镜像
$ kubectl run my-nginx --image=nginx --port=80
# 交互式 shell 的方式运行 pod
$ kubectl run -i --tty my-nginx --image=nginx --port=80 -- sh
# 链接到运行中的容器
$ kubectl attach my-nginx-532658988-10kxd -i
# 查看deployment
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-nginx 1 1 1 1 25m
# 扩展10个副本
$ kubectl scale deployment my-nginx --replicas=10
deployment "my-nginx" scaled
$ kubectl scale deployment/my-nginx --replicas=10 # 作用效果等同上一条命令
deployment "my-nginx" scaled
# 再次显示deployment
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-nginx 10 10 10 1 26m
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
my-nginx-379829228-38hkg 1/1 Running 0 5m
my-nginx-379829228-7j15l 1/1 Running 0 31m
my-nginx-379829228-c8mt3 1/1 Running 0 5m
my-nginx-379829228-f6mm8 1/1 Running 0 5m
my-nginx-379829228-q1rj0 1/1 Running 0 5m
my-nginx-379829228-qg7lf 1/1 Running 0 5m
my-nginx-379829228-rjfbq 1/1 Running 0 5m
my-nginx-379829228-v581r 1/1 Running 0 5m
my-nginx-379829228-wh49w 1/1 Running 0 5m
my-nginx-379829228-wpn98 1/1 Running 0 5m
# 缩扩到1个副本
$ kubectl scale deployment/my-nginx --replicas=1
deployment "my-nginx" scaled
$ kubectl scale deployment my-nginx --replicas=1 # 作用效果等同上一条命令
deployment的更新回滚
$ kubectl create -f nginx.yaml
$ kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-4087004473-4xj74 1/1 Running 0 3m
my-nginx-4087004473-jkptq 1/1 Running 0 3m
my-nginx-4087004473-m55s1 1/1 Running 0 3m
$ kubectl get deployment
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-nginx 3 3 3 3 4m
# 更新应用的镜像从1.7.9版本——>1.9.1
$ kubectl set image deployment/my-nginx nginx=nginx:1.9.1
deployment "my-nginx" image updated
# 确认是否更新成功
$ kubectl rollout status deployment/my-nginx
deployment "my-nginx" successfully rolled out
# 回滚到上一代版本
$ kubectl rollout undo deployment/my-nginx
deployment "my-nginx" rolled back
ConfigMap-容器应用的配置管理
应用部署的一个最佳实践是将应用所需配置信息和程序进行分离，一则程序可以更好的复用，二则能灵活的更改配置从而实现其他功能。
使用configMap替代环境变量
以yaml文件方式创建ConfigMap
# vi special-config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: special-config
namespace: default
data:
special.how: very
special.type: charm
# vi env-config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: env-config
namespace: default
data:
log_level: INFO
可以在Pod中这样使用ConfigMap
# vi configMap.yaml
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: nginx
command: [ "/bin/sh", "-c", "env" ]
env:
- name: SPECIAL_LEVEL_KEY #定义环境变量名称
valueFrom: #key"special.how"对应的值
configMapKeyRef:
name: special-config #环境变量的值
key: special.how
- name: SPECIAL_TYPE_KEY
valueFrom:
configMapKeyRef:
name: special-config
key: special.type
restartPolicy: Never
启动等一系列操作
$ kubectl create -f special-config.yaml
configmap "special-config" created
$ kubectl create -f env-config.yaml
configmap "env-config" created
# 查看ConfigMap
$ kubectl get configmaps
NAME DATA AGE
env-config 1 38m
special-config 2 39m
# 让我们看一下创建的ConfigMap
$ kubectl describe configmap env-config
Name: env-config
Namespace: default
Labels:
Annotations:
Data
====
log_level: 4 bytes
# 查看ConfigMap键的值
$ kubectl get configmaps env-config -o yaml
apiVersion: v1
data:
log_level: INFO
kind: ConfigMap
metadata:
creationTimestamp: 2017-11-30T07:29:49Z
name: env-config
namespace: default
resourceVersion: "285268"
selfLink: /api/v1/namespaces/default/configmaps/env-config
uid: 3f473adf-d5a0-11e7-9830-0800275ae9e7
$ kubectl create -f configMap.yaml
pod "dapi-test-pod" created
# 查看pod，状态ContainerCreating
$ kubectl get pod
NAME READY STATUS RESTARTS AGE
dapi-test-pod 0/1 ContainerCreating 0 3s
# 隔一段时间再查看pod,发现并没有返回什么
$ kubectl get pod
# 显示所有的权限查看pod
$ kubectl get pod --show-all
NAME READY STATUS RESTARTS AGE
dapi-test-pod 0/1 Completed 0 1m
# 查看详情
$ kubectl describe pod dapi-test-pod
Name: dapi-test-pod
Namespace: default
Node: 127.0.0.1/127.0.0.1
Start Time: Thu, 30 Nov 2017 15:32:00 +0800
Labels:
Status: Succeeded
IP:
Controllers:
Containers:
test-container:
Container ID: docker://1ba533f43ee60c02e03dafb7bcb8495fc12264aaab229872df0b289a3c1b9976
Image: nginx
Image ID: docker-pullable://docker.io/nginx@sha256:b81f317384d7388708a498555c28a7cce778a8f291d90021208b3eba3fe74887
Port:
Command:
/bin/sh
-c
env
State: Terminated
Reason: Completed
Exit Code: 0
Started: Thu, 30 Nov 2017 15:32:25 +0800
Finished: Thu, 30 Nov 2017 15:32:25 +0800
Ready: False
Restart Count: 0
Volume Mounts:
Environment Variables:
SPECIAL_LEVEL_KEY:
SPECIAL_TYPE_KEY:
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
No volumes.
QoS Class: BestEffort
Tolerations:
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
3m 3m 1 {default-scheduler } Normal Scheduled Successfully assigned dapi-test-pod to 127.0.0.1
3m 3m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Pulling pulling image "nginx"
3m 2m 2 {kubelet 127.0.0.1} Warning MissingClusterDNS kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Pulled Successfully pulled image "nginx"
2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Created Created container with docker id 1ba533f43ee6; Security:[seccomp=unconfined]
2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Started Started container with docker id 1ba533f43ee6
# 可知container started 成功，进一步查看日志
$ docker logs 1ba
KUBERNETES_SERVICE_PORT=443
KUBERNETES_PORT=tcp://10.254.0.1:443
MY_SERVICE_PORT_80_TCP=tcp://10.254.110.249:80
MY_SERVICE_PORT_443_TCP_ADDR=10.254.110.249
HOSTNAME=dapi-test-pod
MY_SERVICE_PORT_443_TCP_PORT=443
HOME=/root
MY_SERVICE_PORT_443_TCP_PROTO=tcp
MY_SERVICE_SERVICE_PORT_HTTP=80
SPECIAL_TYPE_KEY=charm
MY_SERVICE_SERVICE_PORT_HTTPS=443
MY_SERVICE_PORT_443_TCP=tcp://10.254.110.249:443
MY_SERVICE_SERVICE_HOST=10.254.110.249
KUBERNETES_PORT_443_TCP_ADDR=10.254.0.1
NGINX_VERSION=1.13.7-1~stretch
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
KUBERNETES_PORT_443_TCP_PORT=443
NJS_VERSION=1.13.7.0.1.15-1~stretch
KUBERNETES_PORT_443_TCP_PROTO=tcp
MY_SERVICE_SERVICE_PORT=80
MY_SERVICE_PORT=tcp://10.254.110.249:80
SPECIAL_LEVEL_KEY=very
MY_SERVICE_PORT_80_TCP_ADDR=10.254.110.249
KUBERNETES_PORT_443_TCP=tcp://10.254.0.1:443
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_SERVICE_HOST=10.254.0.1
MY_SERVICE_PORT_80_TCP_PORT=80
PWD=/
MY_SERVICE_PORT_80_TCP_PROTO=tcp
ConfigMap的限制条件
- ConfigMap必须在Pod之前创建才能被使用。
- ConfigMap可以定义其属于哪个Namspece，只有在同一个Namespace中的pod才能引用。
删除Pod
- 有时候deployment、rs、rc、services都为0，但是Pod确存在着。则重启kubelet服务即可。
$ systemctl restart kubelet
补充
# 列出当前节点名
kubectl get node
NAME STATUS AGE
127.0.0.1 Ready 6d
# 已知当前节点名为127.0.0.1,用如下命令即可获得该节点上所有运行节点
$ curl localhost:8080/api/v1/proxy/nodes/127.0.0.1/pods
{"kind":"PodList","apiVersion":"v1","metadata":{},"items":null}
报错
$ sudo kubectl create -f file.yaml
YAML error: found character that cannot start any token
# or
error:yaml: line 15: found a tab character that violate indentation
#file.yaml不可用tab键来空格
$ sudo kubectl create -f mysql-rc.yaml
error: error validating "mysql-rc.yaml": error validating data: [found invalid field app for v1.ObjectMeta, found invalid field value for v1.Container]; if you choose to ignore these errors, turn validation off with --validate=false
---------------------
# kubectl get pod --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
default my-nginx-379829228-b796w 1/1 Running 0 12m
kube-system kubernetes-dashboard-2397086622-46tvx 0/1 ContainerCreating 0 8s
[root@node01 ~]# kubectl logs -f kubernetes-dashboard-2397086622-46tvx --namespace=kube-system
Using HTTP port: 9090
Using apiserver-host location: http://127.0.0.1:8080
Creating API server client for http://127.0.0.1:8080
Error while initializing connection to Kubernetes apiserver. This most likely means that the cluster is misconfigured (e.g., it has invalid apiserver certificates or service accounts configuration) or the --apiserver-host param points to a server that does not exist. Reason: Get http://127.0.0.1:8080/version: dial tcp 127.0.0.1:8080: getsockopt: connection refused
Refer to the troubleshooting guide for more information: https://github.com/kubernetes/dashboard/blob/master/docs/user-guide/troubleshooting.md
我们最好不要越过RC而直接创建Pod,因为Replication Controller会通过RC管理Pod副本。实现自动创建、补足、替换、删除Pod副本，大大提高系统的容灾能力
- 重新调度(Rescheduling)
- 弹性伸缩(Scaling)
- 滚动更新(Rolling Updates)