在Kubernetes中，所有对象都会被指定一个唯一的Name和UID。
用户还可以指定一些不要求唯一性的数据附加到对象上，例如Label和Annotation。
1. Name
Name是创建一个Kubernetes对象时必须指定的，无论是Pod，ReplicaSet或者Deployment等等。如果通过REST API访问的话，形式就如/api/v1/pods/some-name。
一个Name只能由小写字母，-和.组成，并且长度不能超过253个字符。
在同一个命名空间下，同种类型的对象，其Name必须唯一。
2. UID
Kubernetes在创建一个对象时，除了拥有Name以外，还会为其分配一个全局唯一的UID。
参考文章
https://kubernetes.io/docs/concepts/overview/working-with-objects/names/
Kubernetes基本概念之Namespace
Namespace类似于Linux系统中用户的概念，通过将系统内部的对象分配到不同的Namespace中，形成逻辑上的分，便于不同的分组在共享集群资源的同时还能被分别管理。同一Namespace下的Kubenetes对象的Name必须唯一。
常见的 pod, service, replication controller 和 deployment 等都是属于某一个 namespace 的（默认是 default），而 node, persistent volume，namespace 等资源则不属于任何 namespace。
1. Namespace操作
1.1 查看
$ kubectl get namespaces
NAME STATUS AGE
default Active 1d
kube-system Active 1d
kube-public Active 1d 通过上述命令，可以查看到Kubernetes为我们初始化的三个Namespace：
- default：所有未指定Namespace的对象都会被分配在default命名空间。
- kube-system：所有由Kubernetes系统创建的资源都处于这个命名空间。
- kube-public：此命名空间下的资源可以被所有人访问（包括未认证用户）。
1.2 设置Namespace
通过--namespace参数可以在一条命令中指定Namespace，只对单条命令有效。
$ kubectl --namespace=<insert-namespace-name-here> run nginx --image=nginx
$ kubectl --namespace=<insert-namespace-name-here> get pods
还可以绑定一个Namespace到特定的上下文，这样在此上下文中执行的kubectl命令都处于绑定的Namespace下。
$ kubectl config set-context $(kubectl config current-context) --namespace=<insert-namespace-name-here>
# Validate it
$ kubectl config view | grep namespace:
1.3 Namespace和DNS
当你创建一个Service时，Kubernetes会自动创建一个形如<service-name>.<namespace-name>.svc.cluster.local的DNS项。如果集群中另一个服务调用这个服务时，仅仅指定了<service-name>，那么Kubernetes会使用调用方所在的Namespace将<service-name>补全。因此如果调用方和被调用方不处于同一个Namespace，你必须使用包含Namespace的service name（fully qualified domain name (FQDN)）。
参考文章
https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/
https://blog.csdn.net/qq_34701586/article/details/78732470
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 <none> 443/TCP 7d
my-nginx 10.254.255.103 <nodes> 80:32589/TCP 7s
宿主主机内访问该服务
同网段的机器访问该服务
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: <none>
Annotations: <none>
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: <none>
Status: Succeeded
IP:
Controllers: <none>
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: <none>
Environment Variables:
SPECIAL_LEVEL_KEY: <set to the key 'special.how' of config map 'special-config'>
SPECIAL_TYPE_KEY: <set to the key 'special.type' of config map 'special-config'>
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
No volumes.
QoS Class: BestEffort
Tolerations: <none>
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
1
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}
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)
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
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kubernetes一步一步搭建（一）安装与http访问
19297
众所周知，kubernetes（简称k8s）是用于管理docker集群的，最近一段时间一直在折腾环境问题，在此写一篇博客，来帮助像我一样的小白，避免走弯路。一、环境集群环境角色IP地址版本号Doc...
来自： xxb249
helloworld_scut： my-nginx.yaml格式是错的。
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx-demo
spec:
replicas: 3
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80