kubernetes之Kubeadm快速安裝v1.12.0版

通過Kubeadm隻需幾條指令即起一個單機版kubernetes叢集系統，而後快速上手k8s。

在kubeadm中，需手動安裝Docker和kubeket服務，Docker運作容器引擎，kubelet是啟動Pod的核心元件，每一個節點都安裝好kubelet和Docker，那麼運作容器和Pod的環境就準備好了，在此基礎之上，使用Kubeadm工具自動配置kubelet并啟動kubelet服務，将Master所有元件和Node上剩餘的kube-proxy元件都運作為Pod，托管在k8s之上。

伺服器規劃

三台機器：一台master、兩個Node：

k8s-master：10.3.1.20
k8s-node01：10.3.1.21
k8s-node02：10.3.1.25
OS：Ubuntu16.04
Docker：17.03.2-ce

安裝前準備

1、master節點到各Node節點SSH免密登入。

2、時間同步。

3、各Node必須關閉swap：swapoff -a，否則kubelet啟動失敗。

4、各節點主機名和IP加入/etc/hosts解析

安裝Docker

所有k8s節點安裝Docker Daemon：

apt-get update
apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
apt-key fingerprint 0EBFCD88
add-apt-repository \
    "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
    $(lsb_release -cs) \
    stable"
apt-get update
## 列出可安裝的Docker版本
apt-cache madison docker-ce

apt-get install -y docker-ce=17.03.2~ce-0~ubuntu-xenial

安裝完Docker後，設定FORWARD規則為ACCEPT

#預設為DROP
 iptables -P FORWARD ACCEPT

安裝kubeadm工具

所有節點都需要安裝kubeadm

apt-get update && apt-get install -y apt-transport-https curl
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
echo 'deb http://apt.kubernetes.io/ kubernetes-xenial main' >/etc/apt/sources.list.d/kubernetes.list
apt-get update
apt-get install -y  kubeadm

#它會自動安裝kubeadm、kubectl、kubelet、kubernetes-cni、socat

預設情況下，将會安裝目前kubernetes最新版本的kubeadm，也可以安裝指定版本的kubeadm

apt install kubeadm=1.11.3-00

kubeadm init 安裝的kubernetes是哪個版本，取決于 kubeadm 的版本，兩者預設且必須一緻。

安裝完後，設定kubelet服務開機自啟：

systemctl enable kubelet

必須設定Kubelet開機自啟動，才能讓k8s叢集各元件在系統重新開機後自動運作。

部署叢集

有了上面這些基礎設定後，就可以開始用kubeadm init部署k8s叢集了。

在k8s-master上操作

這一步之前確定swap已關閉。

kubeadm init -h可檢視幫助資訊：

root@k8s-master:~# kubeadm  init -h
 ##檢視init可用的參數，這裡使用這兩個參數：
   --pod-network-cidr string ： 自定義Pod網絡
   --ignore-preflight-errors strings： 忽略一些錯誤

開始初始化叢集

root@k8s-master:~# kubeadm init  --pod-network-cidr 192.168.0.0/16 --ignore-preflight-errors=all

輸出如下資訊：

#初始化kubernetes，Kubeadm預設安裝目前最新版本kubernetes
[init] using Kubernetes version: v1.12.0
#安裝之前檢測目前是否符合k8s運作環境，因為忽略了所有錯誤是以這裡很快就通過了。
[preflight] running pre-flight checks
[preflight/images] Pulling images required for setting up a Kubernetes cluster
[preflight/images] This might take a minute or two, depending on the speed of your internet connection
[preflight/images] You can also perform this action in beforehand using 'kubeadm config images pull'
#寫入kubelet相關配置檔案，并啟動kubelet服務
[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[preflight] Activating the kubelet service
#自動生成叢集用到的證書
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [127.0.0.1 ::1]
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [10.3.1.20 127.0.0.1 ::1]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.3.1.20]
[certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"
[certificates] Generated sa key and public key.
#生成kubelet配置資訊寫入相應的檔案
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
#生成pod清單檔案，kubelet将根據此清單檔案建立各元件的Pod
[controlplane] wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
#根據清單目錄開始啟動Pod
[init] waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests" 
[init] this might take a minute or longer if the control plane images have to be pulled
[apiclient] All control plane components are healthy after 20.003530 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.12" in namespace kube-system with the configuration for the kubelets in the cluster
#給Master設定一個labele且設定一個taint
[markmaster] Marking the node k8s-master as master by adding the label "node-role.kubernetes.io/master=''"
[markmaster] Marking the node k8s-master as master by adding the taints [node-role.kubernetes.io/master:NoSchedule]
#叢集的一些基礎設定
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "k8s-master" as an annotation
#設定了一個引導令牌，在節點加入時使用
[bootstraptoken] using token: mwfr7m.57rmd56ghjyu0716
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
#提示master已初始化成功
Your Kubernetes master has initialized successfully!

To start using your cluster, you need to run the following as a regular user:
#需要執行下面三條指令
  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

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/

You can now join any number of machines by running the following on each node
as root:

  kubeadm join 10.3.1.20:6443 --token mwfr7m.57rmd56ghjyu0716 --discovery-token-ca-cert-hash sha256:8fbd33519b0203e9aa03cc882cb5489b5e6ad455f97581b1abf8ceb1dca8f622

#把上面kubeadm join這一句話把這個記錄下來，否則以後找起來有點麻煩，在node端加入時用到。

初始化完成，一台Master節點就部署好了，初始化過程中需要一定時間來pull鏡像，也可以使用下面的指令提前下載下傳好鏡像：

root@k8s-master:~# kubeadm  config images pull 

[config/images] Pulled k8s.gcr.io/kube-apiserver:v1.12.0
[config/images] Pulled k8s.gcr.io/kube-controller-manager:v1.12.0
[config/images] Pulled k8s.gcr.io/kube-scheduler:v1.12.0
[config/images] Pulled k8s.gcr.io/kube-proxy:v1.12.0
[config/images] Pulled k8s.gcr.io/pause:3.1
[config/images] Pulled k8s.gcr.io/etcd:3.2.24
[config/images] Pulled k8s.gcr.io/coredns:1.2.2

#
root@k8s-master:~# docker images 
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-apiserver            v1.12.0             ab60b017e34f        16 hours ago        194 MB
k8s.gcr.io/kube-controller-manager   v1.12.0             07e068033cf2        16 hours ago        164 MB
k8s.gcr.io/kube-scheduler            v1.12.0             5a1527e735da        16 hours ago        58.3 MB
k8s.gcr.io/kube-proxy                v1.12.0             9c3a9d3f09a0        16 hours ago        96.6 MB
k8s.gcr.io/etcd                      3.2.24              3cab8e1b9802        7 days ago          220 MB
k8s.gcr.io/coredns                   1.2.2               367cdc8433a4        4 weeks ago         39.2 MB
k8s.gcr.io/pause                     3.1                 da86e6ba6ca1        9 months ago        742 kB

根據提示執行：

root@k8s-master:~# mkdir -p $HOME/.kube
root@k8s-master:~# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
root@k8s-master:~# sudo chown $(id -u):$(id -g) $HOME/.kube/config

在Node上操作

在所有Node上使用kubeadm join加入叢集：

#確定swap已關閉
#複制在master節點上記錄下的那句話，以加入叢集
root@k8s-node01:~# kubeadm join 10.3.1.20:6443 --token mwfr7m.57rmd56ghjyu0716 --discovery-token-ca-cert-hash sha256:8fbd33519b0203e9aa03cc882cb5489b5e6ad455f97581b1abf8ceb1dca8f622

#加入時也會做一些預檢
[preflight] running pre-flight checks
    [WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs_rr ip_vs_wrr ip_vs_sh ip_vs] or no builtin kernel ipvs support: map[ip_vs:{} ip_vs_rr:{} ip_vs_wrr:{} ip_vs_sh:{} nf_conntrack_ipv4:{}]
you can solve this problem with following methods:
 1. Run 'modprobe -- ' to load missing kernel modules;
2. Provide the missing builtin kernel ipvs support

[discovery] Trying to connect to API Server "10.3.1.20:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://10.3.1.20:6443"
[discovery] Requesting info from "https://10.3.1.20:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "10.3.1.20:6443"
[discovery] Successfully established connection with API Server "10.3.1.20:6443"
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace
[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[preflight] Activating the kubelet service
[tlsbootstrap] Waiting for the kubelet to perform the TLS Bootstrap...
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "k8s-node01" as an annotation

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 master to see this node join the cluster.

init完後，節點已加入群集。

最後，在master節點檢視：

root@k8s-master:~# kubectl get node
NAME          STATUS     ROLES    AGE     VERSION
k8s-master    NotReady   master   6m39s   v1.12.0
k8s-node01   NotReady   <none>   4m31s   v1.12.0
k8s-node02   NotReady   <none>   97s     v1.12.0

去除master的taint，使用master也能被排程pod

root@k8s-master:~# kubectl taint nodes k8s-master node-role.kubernetes.io/master-
node/k8s-master untainted

安裝CNI插件

各Node節點處于"NotReady" ，需要安裝一個CNI網絡插件：

root@k8s-master:~#  kubectl apply -f https://docs.projectcalico.org/v3.1/getting-started/kubernetes/installation/hosted/kubeadm/1.7/calico.yaml
configmap/calico-config configured
daemonset.extensions/calico-etcd created
service/calico-etcd created
daemonset.extensions/calico-node created
deployment.extensions/calico-kube-controllers created
clusterrolebinding.rbac.authorization.k8s.io/calico-cni-plugin created
clusterrole.rbac.authorization.k8s.io/calico-cni-plugin created
serviceaccount/calico-cni-plugin created
clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrole.rbac.authorization.k8s.io/calico-kube-controllers created
serviceaccount/calico-kube-controllers unchanged
root@k8s-master:~#

幾分鐘後，各Node全部Ready：

#各節點已正常運作
root@k8s-master:~# kubectl get node
NAME         STATUS   ROLES    AGE   VERSION
k8s-master   Ready    master   1h   v1.12.0
k8s-node01   Ready    <none>   1h   v1.12.0
k8s-node02   Ready    <none>   1h   v1.12.0

至此，所有元件全部運作：

root@k8s-master:~# kubectl get pod -n kube-system
NAME                                       READY   STATUS    RESTARTS   AGE
calico-etcd-d7v6w                          1/1     Running   0          3m21s
calico-kube-controllers-75fb4f8996-dg7hd   1/1     Running   0          3m20s
calico-node-794nd                          2/2     Running   0          3m19s
calico-node-b852z                          2/2     Running   0          3m19s
calico-node-z7f4n                          2/2     Running   0          3m19s
coredns-576cbf47c7-7svmm                   1/1     Running   0          15h
coredns-576cbf47c7-kzbv2                   1/1     Running   0          15h
etcd-k8s-master                            1/1     Running   0          15h
kube-apiserver-k8s-master                  1/1     Running   0          15h
kube-controller-manager-k8s-master         1/1     Running   0          15h
kube-proxy-7n5z9                           1/1     Running   0          15h
kube-proxy-rwq9g                           1/1     Running   0          15h
kube-proxy-v7qnx                           1/1     Running   0          15h
kube-scheduler-k8s-master                  1/1     Running   0          15h
root@k8s-master:~#

測試叢集

配置kubectl的指令補全功能

指令補全功能由安裝包"bash-completion"提供，Ubuntu系統中預設已安裝。

目前shell生效：
source <(kubectl completion bash)
永久生效：
echo "source <(kubectl completion bash)" >> ~/.bashrc

啟動一個pod驗證叢集是否正常運作。

#run一個deployment
kubectl run -h
Usage:
  kubectl run NAME --image=image [--env="key=value"] [--port=port] [--replicas=replicas] [--dry-run=bool]
[--overrides=inline-json] [--command] -- [COMMAND] [args...] [options]

啟動一個nginx

kubectl run nginx --image=nginx:1.10 --port=80
deployment.apps/nginx created
#檢視
root@k8s-master:~# kubectl get pod -w -o wide
NAME                     READY   STATUS              RESTARTS   AGE   IP       NODE         NOMINATED NODE
nginx-787b58fd95-p9jwl   0/1     ContainerCreating   0          59s   <none>   k8s-node02   <none>
nginx-787b58fd95-p9jwl   1/1   Running   0     70s   192.168.58.193   k8s-node02   <none>

測試nginx正常通路

root@k8s-master:~# curl  -I 192.168.58.193
HTTP/1.1 200 OK
Server: nginx/1.10.3
Date: Sat, 29 Sep 2018 02:42:06 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 31 Jan 2017 15:01:11 GMT
Connection: keep-alive
ETag: "5890a6b7-264"
Accept-Ranges: bytes

把nginx暴露一個端口出來，以使叢集之外能通路

kubectl expose -h 
Usage:
kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name]
[--name=name] [--external-ip=external-ip-of-service] [--type=type] [options]

root@k8s-master:~# kubectl expose deployment nginx --port=801 --target-port=80 --type=NodePort --name nginx-svc
service/nginx-svc exposed
root@k8s-master:~#

檢視服務：

root@k8s-master:~# kubectl get svc
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)         AGE
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP         16h
nginx-svc    NodePort    10.100.84.207   <none>        801:30864/TCP   25s

root@k8s-node01:~# curl 10.3.1.21:30864

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>

iptables -P FORWARD ACCEPT

kubernetes之Kubeadm快速安裝v1.12.0版

伺服器規劃

安裝前準備

安裝Docker

安裝kubeadm工具

部署叢集

在k8s-master上操作

在Node上操作

安裝CNI插件

測試叢集

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