基本概念的理解

k8s是一种编排工具，类似于docker-compose，但是应用比后者广泛。

k8s水平扩展访问，本质上是增加pod，且新增的pod均匀分布在不同的机器上。

概念的层级关系k8s–node(对应一台物理机器)–pod。

容器有docker，rocket。k8s与docker的组合最常用。

pod是k8s最小调度单元。每个pod有自己独立的ip。一个pod里面多个docker container的ip都是一样的。pod里面可以开多个docker container。一般情况下一个pod只开一个container，当同一个pod开多个container的时候，多个容器的协作关系采用localhost的方式通信。

节点中的kubelet相当于node server的作用，会上报节点中不同pod的信息。

kublet-pod-docker-container三者之间的关系，类似操作系统中的调度器-进程-线程之间的关系。

所有的数据交互都是通过server-api组件来完成。

etcd默认在master节点上。

service是用来统一管理pod的组件，怎样将pod分发到不同的node。对外表现为一个访问入口，可以认为是一个用来做负载均衡的网管。

参考书：《k8s权威指南》

实操

准备工作

1. 禁用swap

sudo swapoff -a #无输出

注释掉/etc/fstab中关于swap语句

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-UmKR3G1L-1664502154890)(D:\Documents\fiberhome\MarkDown\Images\0voice\2022-09-19 194506.png)]

2. 关闭防火墙

master@ubuntu:~$ sudo systemctl stop firewalld #提示防火墙服务没有导入
Failed to stop firewalld.service: Unit firewalld.service not loaded.
master@ubuntu:~$ sudo systemctl disable firewalld
Failed to disable unit: Unit file firewalld.service does not exist.

3. 禁用selinux

更新ubuntu源

sudo apt install selinux-utils #安装不成功，跟mysql有关系
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. 

这里属于历史遗留问题，参考另一篇解决方法。解决后，更新软件源，用来更快安装selinux。

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

更新文件内容，用阿里源替换

sudo gedit /etc/apt/sources.list
#  阿里源
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

selinux安装完成后，执行

master@ubuntu:~$ sudo setenforce 0
setenforce: SELinux is disabled

4. 修改主机名

master@ubuntu:~$ sudo vim /etc/hosts
master@ubuntu:~$ sudo /etc/init.d/networking restart 
[ ok ] Restarting networking (via systemctl): networking.service.

设置主机名

sudo hostnamectl set-hostname qiu-k8s-m

键入hostnamectl显示主机名已修改成功

master@ubuntu:~$ hostnamectl
   Static hostname: qiu-k8s-m
         Icon name: computer-vm
           Chassis: vm
               ... ...

经过重启后，终端中会显示改过后的主机名

master@qiu-k8s-m:~$ 

5. 安装docker

已经安装，输入docker -v可显示版本

master@qiu-k8s-m:~$ docker -v
Docker version 20.10.17, build 100c701

将当前用户加入docker组，避免每次docker命令都用sudo。但是要使修改后的/etc/group生效得重启机器。

sudo groupadd docker #打开/etc/group最后一行会有docker:x:GID:
sudo usermod -aG docker $USER #将当前用户加入到GID:后面

测试docker能否正常拉取镜像

master@qiu-k8s-m:~$ docker run -it ubuntu bash
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
2b55860d4c66: Pull complete 
Digest: sha256:20fa2d7bb4de7723f542be5923b06c4d704370f0390e4ae9e1c833c8785644c1
Status: Downloaded newer image for ubuntu:latest
root@32cfec738c47:/# 

能正常显示以上信息，则表示docker安装成功。

如果拉取速度太慢，是因为要从Docker Hub上下载，可修改相关文件

sudo vim /etc/docker/daemon.json
#添加
{ "registry-mirrors": ["https://alzgoonw.mirror.aliyuncs.com"], "live-restore": true }

并且执行

sudo systemctl daemon-reload 
sudo systemctl restart docker

来重启docker服务。更新后再拉取镜像就快很多了。

如果启动docker服务出现问题，可能是/etc/docker/daemon.json改的有问题，使用dockerd --debug排查

master@qiu-k8s-m:~$ sudo dockerd --debug
unable to configure the Docker daemon with file /etc/docker/daemon.json: the following directives don't match any configuration option: __registry-mirrors

准备安装kubectl，kubelet，kubeadm

添加秘钥

master@qiu-k8s-m:~$ curl https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | sudo apt-key add -
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2537  100  2537    0     0    898      0  0:00:02  0:00:02 --:--:--   898
OK

添加Kubernetes软件源，采用ustc源

sudo vim /etc/apt/source.list.d/kubernetes.list

添加内容

deb http://mirrors.ustc.edu.cn/kubernetes/apt kubernetes-xenial main

由于xenial是ubuntu16.04的代号，而实验的机器是18.04，理应将xenial替换成bionic，但换过之后反而找不到源，于是再换回来。

安装kubelet，kubelet，kubeadm

更新源，然后使用apt-get install的方式安装

sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo systemctl enable kubelet

查看节点试试

master@qiu-k8s-m:~$ kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?

或者报这个错误

master@qiu-k8s-m:~$ sudo kubectl get nodes
Unable to connect to the server: dial tcp 192.168.230.246:6443: connect: no route to host

因为还没有布置节点，所以无节点显示。

将其他两个节点按同样的步骤过一遍。

配置master

配置环境变量

sudo vim /etc/profile

末尾加入

export KUBECONFIG=/etc/kubernetes/admin.conf

立即生效

source /etc/profile

重启kubelet

sudo systemctl daemon-reload 
sudo systemctl restart kubelet

初始化kubeadm

sudo kubeadm init --image-repository registry.aliyuncs.com/google_containers --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.230.246 --ignore-preflight-errors=NumCPU

报错

W0921 11:13:33.282440    3157 version.go:104] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get "https://dl.k8s.io/release/stable-1.txt": context deadline exceeded (Client.Timeout exceeded while awaiting headers)
W0921 11:13:33.282636    3157 version.go:105] falling back to the local client version: v1.25.1
[init] Using Kubernetes version: v1.25.1
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR CRI]: container runtime is not running: output: E0921 11:13:33.473505    3198 remote_runtime.go:948] "Status from runtime service failed" err="rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
time="2022-09-21T11:13:33+08:00" level=fatal msg="getting status of runtime: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
, error: exit status 1
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

解决办法，删掉/etc/containerd/config.toml文件，重启容器服务

sudo rm -rf /etc/containerd/config.toml 
systemctl restart containerd

可以跑起来，但是很慢，不过提示可以先执行sudo kubeadm config images pull这个命令

master@qiu-k8s-m:~$ sudo kubeadm init --image-repository registry.aliyuncs.com/google_containers --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.230.246 --ignore-preflight-errors=NumCPU
[sudo] password for master: 
[init] Using Kubernetes version: v1.25.1
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
^C

于是先拉镜像，同样很慢，不过还是熬结束了

master@qiu-k8s-m:~$ sudo kubeadm config images pull --image-repository registry.aliyuncs.com/google_containers
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-apiserver:v1.25.1
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-controller-manager:v1.25.1
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-scheduler:v1.25.1
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-proxy:v1.25.1
[config/images] Pulled registry.aliyuncs.com/google_containers/pause:3.8
[config/images] Pulled registry.aliyuncs.com/google_containers/etcd:3.5.4-0
[config/images] Pulled registry.aliyuncs.com/google_containers/coredns:v1.9.3

再回来执行init那条语句，但是遇到错误

...
[kubelet-check] Initial timeout of 40s passed.

Unfortunately, an error has occurred:
	timed out waiting for the condition

This error is likely caused by:
	- The kubelet is not running
	- The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)

If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
	- 'systemctl status kubelet'
	- 'journalctl -xeu kubelet'
...

说是kubelet没有跑起来？那就再执行下reload

error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-apiserver.yaml]: /etc/kubernetes/manifests/kube-apiserver.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-controller-manager.yaml]: /etc/kubernetes/manifests/kube-controller-manager.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-scheduler.yaml]: /etc/kubernetes/manifests/kube-scheduler.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-etcd.yaml]: /etc/kubernetes/manifests/etcd.yaml already exists
	[ERROR Port-10250]: Port 10250 is in use

仍然报错，显示端口已在使用。键入kubeadm reset，会删掉一些东西。重新执行init语句，会在

[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[kubelet-check] Initial timeout of 40s passed

等好一会，然后重新出现

Unfortunately, an error has occurred:
	timed out waiting for the condition
...

查来查去，可能是之前删除/etc/containerd/config.toml文件导致，因此再新建，加入一些信息

先在当前目录生成这个文件

containerd config default > config.toml

打开文件，将k8s.gcr.io替换为registry.cn-hangzhou.aliyuncs.com/google_containers

 60     restrict_oom_score_adj = false
 61     sandbox_image = "k8s.gcr.io/pause:3.6"
 62     selinux_category_range = 1024

改完后

 60     restrict_oom_score_adj = false
 61     sandbox_image = "registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.6"
 62     selinux_category_range = 1024

将改完后的config.toml文件移动到/etc/containerd/下（当然也可以直接在/etc/containerd/目录下建文件，再修改）

再次执行init那句，仍然报错

....
This error is likely caused by:
	- The kubelet is not running
	- The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)

If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
	- 'systemctl status kubelet'
	- 'journalctl -xeu kubelet'
....

于是决定按照提示在init这句后加上–v=6来获取更详细的信息，可以看到

...
I0926 22:36:31.414225   86362 round_trippers.go:553] GET https://192.168.230.246:6443/healthz?timeout=10s  in 2720 milliseconds
I0926 22:36:34.485995   86362 round_trippers.go:553] GET https://192.168.230.246:6443/healthz?timeout=10s  in 2792 milliseconds
I0926 22:36:37.557797   86362 round_trippers.go:553] GET https://192.168.230.246:6443/healthz?timeout=10s  in 2863 milliseconds
[kubelet-check] Initial timeout of 40s passed.
I0926 22:36:40.630317   86362 round_trippers.go:553] GET https://192.168.230.246:6443/healthz?timeout=10s  in 2935 milliseconds
I0926 22:36:43.701762   86362 round_trippers.go:553] GET https://192.168.230.246:6443/healthz?timeout=10s  in 3007 milliseconds
...

一直重复出现这几句，显然是健康检查时，连接主机地址超时了。通过ifconfig查看自己的ip已经改变，输入了一个不可用的ip，更改后，sudo kubeadm reset，再次init，终于出现了想要的输出

...
[addons] Applied essential addon: kube-proxy
I0926 22:45:05.364595   88564 loader.go:374] Config loaded from file:  /etc/kubernetes/admin.conf
I0926 22:45:05.366180   88564 loader.go:374] Config loaded from file:  /etc/kubernetes/admin.conf

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.230.130:6443 --token 65rht0.rs2weic09flv5o8s \
	--discovery-token-ca-cert-hash sha256:193cc3031acdde64264aba3b186e25462a2c8707b6d9bc27ba92393962d5eece 

如果忘记保存join节点的token值，可输入命令

sudo kubeadm token create --print-join-command

根据以上提示需要输入

mkdir -p $HOME/.kube  
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config  
sudo chown $(id -u):$(id -g) $HOME/.kube/config 

接着安装flannel网络组件

sudo kubectl apply -f  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

稍等一会执行可以看到ready的状态

master@qiu-k8s-m:~$ sudo kubectl get node
NAME        STATUS   ROLES           AGE   VERSION
qiu-k8s-m   Ready    control-plane   20m   v1.25.1

执行init的过程中，由于旧的命令导致端口在使用，可以reset重设

[init] Using Kubernetes version: v1.25.2
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR Port-6443]: Port 6443 is in use
	[ERROR Port-10259]: Port 10259 is in use
	[ERROR Port-10257]: Port 10257 is in use
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-apiserver.yaml]: /etc/kubernetes/manifests/kube-apiserver.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-controller-manager.yaml]: /etc/kubernetes/manifests/kube-controller-manager.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-scheduler.yaml]: /etc/kubernetes/manifests/kube-scheduler.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-etcd.yaml]: /etc/kubernetes/manifests/etcd.yaml already exists
	[ERROR Port-10250]: Port 10250 is in use
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

端口被占用，重置试试

sudo kubeadm reset

重启kubeadm可以解决这个问题。

从节点配置

执行join那句报错

[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR CRI]: container runtime is not running: output: E0927 21:58:31.253378   27048 remote_runtime.go:948] "Status from runtime service failed" err="rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
time="2022-09-27T21:58:31+08:00" level=fatal msg="getting status of runtime: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
, error: exit status 1
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

初步判断是container有关的错误，查到这个资料，解决办法为

rm -rf /etc/containerd/config.toml
systemctl restart containerd

后再执行join那句，最后能看到这个提示

...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
...

表示把当前node加入到集群了，但是输入get nodes这句，仍然有报错

The connection to the server localhost:8080 was refused - did you specify the right host or port?

参考这篇，将主节点/etc/kubenetes/admin.conf拷贝到从节点的指定目录

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

再次执行，可看到节点信息列表

NAME         STATUS     ROLES           AGE   VERSION
qiu-k8s-m    Ready      control-plane   82m   v1.25.1
qiu-k8s-n2   NotReady   <none>          10m   v1.25.1

最后安装flannel网络组件

kubectl apply -f  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

可能是网络连接错误

The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?

那么换种方式，将主节点的/etc/cni拷贝到从节点下的相同目录

cp -r /etc/cni /mnt/
sudo mv  /mnt/cni /etc/

告一段落。

yaml文件里kind有四种类型，Pod，ReolicationController，Deployment，Service。

yaml文件tab和空格不能混用，不支持tab缩进。NodePort是对外提供的端口。

重新配置master节点和从节点，有错误如下

Unable to connect to the server: x509: certificate signed by unknown authority (possibly because of "crypto/rsa: verification error" while trying to verify candidate authority certificate "kubernetes")

这是由于在sudo kubeadm reset时没有删除~/.kube/config文件所致(因为这个文件是手动拷过去的)，解决办法重新拷一份

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

从节点~/.kube/config也需要从主节点拷过去。

为什么配的从节点没有内部的ip?

通过查看pod详情

sudo kubectl describe pod httpd

错误细节

坑太多。。。未完待续