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云原生之容器编排实践-在CentOS7上安装minikube
发布：2022-09-03 Saturday
标签：CloudNative,Docker,Kubernetes
目录[-]
背景
前面做了一些基础的铺垫后，终于进入正题了。
作为初学者，为避免在裸金属主机上搭建 Kubernetes 集群的复杂度，以及使用云服务商提供的容器编排服务的一脸懵逼等打击信心的深坑，建议使用 minikube 来进入 Kubernetes 的世界。
Minikube 是一个用于在本地机器上运行 Kubernetes 集群的工具。使用 Minikube 有以下几个好处：
-
学习和开发环境：
Minikube提供了一个轻量级的Kubernetes环境，可以在本地机器上快速搭建和测试Kubernetes应用程序。这对于学习和开发Kubernetes相关的技术非常有帮助。 -
离线环境：
Minikube可以在没有互联网连接的情况下运行，这对于在没有稳定网络连接的环境中进行开发和测试非常有用。 -
快速部署和验证：使用
Minikube可以快速部署和验证Kubernetes应用程序，而无需依赖复杂的生产环境。这对于快速迭代和验证想法非常有帮助。 -
多平台支持：
Minikube支持在多个操作系统上运行，包括Windows、Mac和Linux。这使得开发人员可以在自己喜欢的操作系统上使用Kubernetes。
总而言之， Minikube 是一个方便、灵活和易于使用的工具，可以帮助开发人员在本地机器上快速搭建和测试 Kubernetes 应用程序。
系统环境
采用一台虚拟机进行实践。。
- 系统信息
[root@k8s0 local]# uname -a
Linux k8s0 3.10.0-1127.el7.x86_64 #1 SMP Tue Mar 31 23:36:51 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
[root@k8s0 local]# cat /proc/version
Linux version 3.10.0-1127.el7.x86_64 (mockbuild@kbuilder.bsys.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-39) (GCC) ) #1 SMP Tue Mar 31 23:36:51 UTC 2020
[root@k8s0 local]# cat /etc/redhat-release
CentOS Linux release 7.8.2003 (Core)
- 配置信息
内存：4G
处理器：2*2
硬盘：100G
安装Minikube
前提是需要具备 Docker 环境
[root@k8s0 ~]# docker -v
Docker version 20.10.17, build 100c701
[root@k8s0 ~]# systemctl status docker
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Docs: https://docs.docker.com
[root@k8s0 ~]# systemctl start docker
[root@k8s0 ~]# systemctl enable docker
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
[root@k8s0 ~]# systemctl stop firewalld
[root@k8s0 ~]# systemctl disable firewalld
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
下载安装并启动
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube
按照官方文档：https://minikube.sigs.k8s.io/docs/start/，我们下载安装后，直接通过 minikube start 就结束战斗了。然而，我就是死活起不来，报出各种错误。
后来，参考了 GitHub 上的 Issue ：https://github.com/kubernetes/minikube/issues/14477，启动时指定 Kubernetes 的版本号就可以启动了。
minikube start --force --kubernetes-version=v1.23.1
不过，如果关闭防火墙后没有重启Docker，就会遇到下面的错误信息。
Error response from daemon: Failed to Setup IP tables: Unable to enable SKIP DNAT rule: (iptables failed: iptables –wait -t nat -I DOCKER -i br-af6aa0eafdec -j RETURN: iptables: No chain/target/match by that name.
解决方案：关闭防火墙后需要重启 Docker 服务，然后再指定 Kubernetes 的版本号启动 minikube 即可。
[root@k8s0 local]# systemctl restart docker
[root@k8s0 local]# minikube start --force --kubernetes-version=v1.23.1
* Centos 7.8.2003 上的 minikube v1.26.0
! minikube skips various validations when --force is supplied; this may lead to unexpected behavior
* 自动选择 docker 驱动。其他选项：none, ssh
* The "docker" driver should not be used with root privileges. If you wish to continue as root, use --force.
* If you are running minikube within a VM, consider using --driver=none:
* https://minikube.sigs.k8s.io/docs/reference/drivers/none/
* Using Docker driver with root privileges
* Starting control plane node minikube in cluster minikube
* Pulling base image ...
> index.docker.io/kicbase/sta...: 0 B [_____________________] ?% ? p/s 2m1s
! minikube was unable to download gcr.io/k8s-minikube/kicbase:v0.0.32, but successfully downloaded docker.io/kicbase/stable:v0.0.32 as a fallback image
* Creating docker container (CPUs=2, Memory=2200MB) ...
! This container is having trouble accessing https://k8s.gcr.io
* To pull new external images, you may need to configure a proxy: https://minikube.sigs.k8s.io/docs/reference/networking/proxy/
* 正在 Docker 20.10.17 中准备 Kubernetes v1.23.1…
- Generating certificates and keys ...
- Booting up control plane ...
- Configuring RBAC rules ...
* Verifying Kubernetes components...
- Using image gcr.io/k8s-minikube/storage-provisioner:v5
* Enabled addons: default-storageclass, storage-provisioner
* kubectl not found. If you need it, try: 'minikube kubectl -- get pods -A'
* Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default
安装kubectl
直接通过 kubectl 命令无法访问，可通过 minikube kubectl 或者单独安装 kubectl ，或者起别名： alias kubectl="minikube kubectl --"
下载地址：https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/
[root@k8s0 local]# kubectl get node
-bash: kubectl: 未找到命令
[root@k8s0 local]# minikube kubectl -- get pods -A
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-64897985d-rcrjq 1/1 Running 0 8m31s
kube-system etcd-minikube 1/1 Running 0 8m43s
kube-system kube-apiserver-minikube 1/1 Running 0 8m43s
kube-system kube-controller-manager-minikube 1/1 Running 0 8m43s
kube-system kube-proxy-6ffnk 1/1 Running 0 8m32s
kube-system kube-scheduler-minikube 1/1 Running 0 8m43s
kube-system storage-provisioner 1/1 Running 1 (8m9s ago) 8m40s
# 下载安装kubectl
[root@k8s0 local]# curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 154 100 154 0 0 217 0 --:--:-- --:--:-- --:--:-- 217
100 43.5M 100 43.5M 0 0 7820k 0 0:00:05 0:00:05 --:--:-- 10.1M
[root@k8s0 local]# install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
# 查看版本，验证安装
[root@k8s0 local]# kubectl version --client
WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short. Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"1", Minor:"24", GitVersion:"v1.24.3", GitCommit:"aef86a93758dc3cb2c658dd9657ab4ad4afc21cb", GitTreeState:"clean", BuildDate:"2022-07-13T14:30:46Z", GoVersion:"go1.18.3", Compiler:"gc", Platform:"linux/amd64"}
Kustomize Version: v4.5.4
minikube基本使用
kubectl 是一个用来跟 K8S 集群进行交互的命令行工具。显然，这里只有一个节点。
常用控制命令
# 查看节点
[root@k8s0 local]# kubectl get node
NAME STATUS ROLES AGE VERSION
minikube Ready control-plane,master 10m v1.23.1
# 启动集群
minikube start
# 停止集群
minikube stop
# 清空集群
minikube delete --all
# 安装集群可视化 Web UI 控制台
minikube dashboard
Dashboard
[root@k8s0 local]# minikube dashboard
* 正在开启 dashboard ...
- Using image kubernetesui/dashboard:v2.6.0
- Using image kubernetesui/metrics-scraper:v1.0.8
* 正在验证 dashboard 运行情况 ...
* Launching proxy ...
* 正在验证 proxy 运行状况 ...
http://127.0.0.1:36124/api/v1/namespaces/kubernetes-dashboard/services/http:kubernetes-dashboard:/proxy/
# 新开一个tab
[root@k8s0 ~]# kubectl proxy --port=8000 --address='192.168.44.142' --accept-hosts='^.*' &
然后通过链接访问：http://192.168.44.142:8000/api/v1/namespaces/kubernetes-dashboard/services/http:kubernetes-dashboard:/proxy/#/workloads?namespace=default
部署应用
# 根据官方文档，部署一个已有应用
[root@k8s0 ~]# kubectl create deployment hello-minikube --image=k8s.gcr.io/echoserver:1.4
# 查看pod
[root@k8s0 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube-7bc9d7884c-bz4q8 0/1 ImagePullBackOff 0 51s
# 状态错误：ErrImagePull
[root@k8s0 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube-7bc9d7884c-bz4q8 0/1 ErrImagePull 0 56s
# 排查原因，查看事件
[root@k8s0 ~]# kubectl get events
5m43s Warning Failed pod/hello-minikube-7bc9d7884c-bz4q8 Error: ErrImagePull
5m32s Normal BackOff pod/hello-minikube-7bc9d7884c-bz4q8 Back-off pulling image "k8s.gcr.io/echoserver:1.4"
5m32s Warning Failed pod/hello-minikube-7bc9d7884c-bz4q8 Error: ImagePullBackOff
6m52s Warning Failed pod/hello-minikube-7bc9d7884c-bz4q8 Failed to pull image "k8s.gcr.io/echoserver:1.4": rpc error: code = Unknown desc = Error response from daemon: Get "https://k8s.gcr.io/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
49m Normal SuccessfulCreate replicaset/hello-minikube-7bc9d7884c Created pod: hello-minikube-7bc9d7884c-bz4q8
49m Normal ScalingReplicaSet deployment/hello-minikube Scaled up replica set hello-minikube-7bc9d7884c to 1
从事件信息中可以看到，拉取镜像失败，怀疑是网络问题。以下我们改为国内容器镜像进行拉取部署。
# 先删除deployment和pod
[root@k8s0 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube-7bc9d7884c-bz4q8 0/1 ErrImagePull 0 41m
[root@k8s0 ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
hello-minikube 0/1 1 0 44m
[root@k8s0 ~]# kubectl delete deployment hello-minikube
deployment.apps "hello-minikube" deleted
[root@k8s0 ~]# kubectl get deployment
No resources found in default namespace.
[root@k8s0 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube-7bc9d7884c-bz4q8 0/1 Terminating 0 45m
[root@k8s0 ~]# kubectl get pod
No resources found in default namespace.
# 更改为国内镜像，重新部署应用，成功
[root@k8s0 ~]# kubectl create deployment hello-minikube --image=registry.cn-hangzhou.aliyuncs.com/google_containers/echoserver:1.4
deployment.apps/hello-minikube created
[root@k8s0 ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
hello-minikube 0/1 1 0 12s
[root@k8s0 ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-minikube-58647b77b8-srpbq 1/1 Running 0 18s
暴露并访问服务
# 将部署暴露为服务
[root@k8s0 ~]# kubectl expose deployment hello-minikube --type=NodePort --port=8080
service/hello-minikube exposed
# 获取服务的URL
[root@k8s0 ~]# minikube service --url hello-minikube
http://192.168.76.2:31061
# 如果终端有浏览器，直接打开
[root@k8s0 ~]# minikube service hello-minikube
|-----------|----------------|-------------|---------------------------|
| NAMESPACE | NAME | TARGET PORT | URL |
|-----------|----------------|-------------|---------------------------|
| default | hello-minikube | 8080 | http://192.168.76.2:31061 |
|-----------|----------------|-------------|---------------------------|
* 正通过默认浏览器打开服务 default/hello-minikube...
http://192.168.76.2:31061
# 查看所有服务
[root@k8s0 ~]# kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-minikube NodePort 10.107.201.188 <none> 8080:31061/TCP 34d
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 34d
# 查看指定服务
[root@k8s0 ~]# kubectl get services hello-minikube
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-minikube NodePort 10.107.201.188 <none> 8080:31061/TCP 34d
# 访问服务
[root@k8s0 ~]# curl http://192.168.76.2:31061
CLIENT VALUES:
client_address=172.17.0.1
command=GET
real path=/
query=nil
request_version=1.1
request_uri=http://192.168.76.2:8080/
SERVER VALUES:
server_version=nginx: 1.10.0 - lua: 10001
HEADERS RECEIVED:
accept=*/*
host=192.168.76.2:31061
user-agent=curl/7.29.0
BODY:
-no body in request-
Reference
If you have any questions or any bugs are found, please feel free to contact me.
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