kubeadm1.13安装

Posted

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了kubeadm1.13安装相关的知识,希望对你有一定的参考价值。

前言

kubeadm 快速安装kubernetes集群,kubeadm 主要功能已经GA,除了高可用 还在alpha。功能如下图

Area Maturity Level
Command line UX GA
Implementation GA
Config file API beta
CoreDNS GA
kubeadm alpha subcommands alpha
High availability alpha
DynamicKubeletConfig alpha
Self-hosting alpha

当前我们线上稳定运行的Kubernetes集群是使用pod形式部署的高可用集群,这里体验Kubernetes 1.13中的kubeadm是为了了解官方对集群初始化和配置方面的最佳方式

1.准备

1.1系统配置

在安装之前,需要先做如下准备。三台CentOS 7.5主机如下:

cat /etc/hosts
192.168.1.57 master
192.168.1.33 node1
192.168.1.34 node2

如果各个主机启用了防火墙,需要开放Kubernetes各个组件所需要的端口,可以查看Installing kubeadm中的”Check required ports”一节。 这里简单起见在各节点禁用防火墙:

systemctl stop firewalld
systemctl disable firewalld

禁用SELINUX:

setenforce 0
vi /etc/selinux/config
SELINUX=disabled

创建/etc/sysctl.d/k8s.conf文件,添加如下内容:

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1

如果准备使用ipvs 模式node节点添加keepalive配置如下

net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 10

相关issue:
https://github.com/moby/moby/issues/31208

执行命令使修改生效。

modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf

##1.2kube-proxy开启ipvs的前置条件
由于ipvs已经加入到了内核的主干,所以为kube-proxy开启ipvs的前提需要加载以下的内核模块:

ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4

在所有的Kubernetes节点node1和node2上执行以下脚本:

cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

上面脚本创建了的/etc/sysconfig/modules/ipvs.modules文件,保证在节点重启后能自动加载所需模块。 使用lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已经正确加载所需的内核模块。

接下来还需要确保各个节点上已经安装了ipset软件包yum install ipset。 为了便于查看ipvs的代理规则,最好安装一下管理工具ipvsadm yum install ipvsadm。

如果以上前提条件如果不满足,则即使kube-proxy的配置开启了ipvs模式,也会退回到iptables模式。

1.3安装Docker

Kubernetes从1.6开始使用CRI(Container Runtime Interface)容器运行时接口。默认的容器运行时仍然是Docker,使用的是kubelet中内置dockershim CRI实现。

安装docker的yum源:

cd /etc/yum.repos.d/
wget https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/docker-ce.repo

查看最新的Docker版本:

yum list docker-ce.x86_64  --showduplicates |sort -r
docker-ce.x86_64            3:18.09.0-3.el7                     docker-ce-stable
docker-ce.x86_64            18.06.1.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.06.0.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.03.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            18.03.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.12.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.12.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.09.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.09.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.2.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.3.ce-1.el7                    docker-ce-stable
docker-ce.x86_64            17.03.2.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.0.ce-1.el7.centos             docker-ce-stable

Kubernetes 1.12已经针对Docker的1.11.1, 1.12.1, 1.13.1, 17.03, 17.06, 17.09, 18.06等版本做了验证,需要注意Kubernetes 1.12最低支持的Docker版本是1.11.1。Kubernetes 1.13对Docker的版本依赖方面没有变化。

确认一下iptables filter表中FOWARD链的默认策略(pllicy)为ACCEPT。

iptables -nvL
Chain INPUT (policy ACCEPT 263 packets, 19209 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 DOCKER-USER  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 DOCKER-ISOLATION-STAGE-1  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ACCEPT     all  --  *      docker0  0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
    0     0 DOCKER     all  --  *      docker0  0.0.0.0/0            0.0.0.0/0
    0     0 ACCEPT     all  --  docker0 !docker0  0.0.0.0/0            0.0.0.0/0
    0     0 ACCEPT     all  --  docker0 docker0  0.0.0.0/0            0.0.0.0/0

Docker从1.13版本开始调整了默认的防火墙规则,禁用了iptables filter表中FOWARD链,这样会引起Kubernetes集群中跨Node的Pod无法通信。docker在后面的18版本又改回来了。

2.使用kubeadm部署Kubernetes

2.1 安装kubeadm和kubelet

下面在各节点安装kubeadm和kubelet:
使用阿里云k8s 仓,记得禁用check

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
       http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF
yum install -y kubelet-1.13.1 kubeadm-1.13.1 kubectl-1.13.1

运行kubelet --help可以看到原来kubelet的绝大多数命令行flag参数都被DEPRECATED了,而官方推荐我们使用--config指定配置文件,并在配置文件中指定原来这些flag所配置的内容。具体内容可以查看这里Set Kubelet parameters via a config file。这也是Kubernetes为了支持动态Kubelet配置(Dynamic Kubelet Configuration)才这么做的,参考Reconfigure a Node’s Kubelet in a Live Cluster

kubelet的配置文件必须是json或yaml格式,具体可查看这里。

Kubernetes 1.8开始要求关闭系统的Swap,如果不关闭,默认配置下kubelet将无法启动。

因为我的机器都开启了swap,关闭swap可能会对其他服务产生影响,所以这里修改kubelet的配置去掉这个限制。 之前的Kubernetes版本我们都是通过kubelet的启动参数--fail-swap-on=false去掉这个限制的。前面已经分析了Kubernetes不再推荐使用启动参数,而推荐使用配置文件。 所以这里我们改成配置文件配置的形式。

查看/etc/systemd/system/kubelet.service.d/10-kubeadm.conf,看到了下面的内容:

# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

上面显示kubeadm部署的kubelet的配置文件--config=/var/lib/kubelet/config.yaml,实际去查看/var/lib/kubelet和这个config.yaml的配置文件都没有被创建。 可以猜想肯定是运行kubeadm初始化集群时会自动生成这个配置文件,而如果我们不关闭Swap的话,第一次初始化集群肯定会失败的。

所以还是老老实实的回到使用kubelet的启动参数--fail-swap-on=false去掉必须关闭Swap的限制。 修改/etc/sysconfig/kubelet,加入:

KUBELET_EXTRA_ARGS=--fail-swap-on=false

2.2 使用kubeadm init初始化集群

在各节点开机启动kubelet服务:

systemctl enable kubelet.service

因为默认初始镜像是gcr.io的,如果机器不×××是pull 不下来的,所以需要我们提前下载下来,并放到私有仓。

查看镜像版本

kubeadm config images list

k8s.gcr.io/kube-apiserver:v1.13.1
k8s.gcr.io/kube-controller-manager:v1.13.1
k8s.gcr.io/kube-scheduler:v1.13.1
k8s.gcr.io/kube-proxy:v1.13.1
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.2.24
k8s.gcr.io/coredns:1.2.6

生成pull命令

kubeadm config images list |sed -e ‘s/^/docker pull /g‘

下载镜像,并且上传到私有仓

docker images|grep gcr.io|awk ‘{print "docker tag ",$1":"$2,$1":"$2}‘|sed ‘s#k8s.gcr.io#docker.foxchan.com/google_containers#2‘

docker tag  k8s.gcr.io/kube-proxy:v1.13.1 docker.foxchan.com/google_containers/kube-proxy:v1.13.1
docker tag  k8s.gcr.io/kube-apiserver:v1.13.1 docker.foxchan.com/google_containers/kube-apiserver:v1.13.1
docker tag  k8s.gcr.io/kube-controller-manager:v1.13.1 docker.foxchan.com/google_containers/kube-controller-manager:v1.13.1
docker tag  k8s.gcr.io/kube-scheduler:v1.13.1 docker.foxchan.com/google_containers/kube-scheduler:v1.13.1
docker tag  k8s.gcr.io/etcd:3.2.24 docker.foxchan.com/google_containers/etcd:3.2.24
docker tag  k8s.gcr.io/coredns:1.2.6 docker.foxchan.com/google_containers/coredns:1.2.6
docker tag  k8s.gcr.io/pause:3.1 docker.foxchan.com/google_containers/pause:3.1

2.2.1通过配置文件安装

kubeadm config print init-defaults >kubeadm.conf

将配置文件的imageRepository: 修改为自己的私有仓
imageRepository: docker.emarbox.com/google_containers

kubernetesVersion 改为自有版本
kubernetesVersion: v1.13.1

kubeadm config images list --config kubeadm.conf
kubeadm config images pull --config kubeadm.conf
kubeadm init --config kubeadm.conf

2.2.2 通过参数化安装

kubeadm init    --kubernetes-version=v1.13.1    --pod-network-cidr=10.244.0.0/16    --apiserver-advertise-address=101.254.242.57    --ignore-preflight-errors=Swap    --token-ttl 0    --image-repository docker.emarbox.com/google_containers

--token-ttl 0 初始化的时候指定token不过期
如果token过期了,用以下步骤重新生成
创建新的token

kubeadm token create

获取ca证书sha256编码hash值

openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed ‘s/^.* //‘

因为我们选择flannel作为Pod网络插件,所以上面的命令指定–pod-network-cidr=10.244.0.0/16。

[init] Using Kubernetes version: v1.13.1
[preflight] Running pre-flight checks
        [WARNING Swap]: running with swap on is not supported. Please disable swap
[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‘
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [node1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.61.11]
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [node1 localhost] and IPs [192.168.61.11 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [node1 localhost] and IPs [192.168.61.11 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[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
[apiclient] All control plane components are healthy after 19.506551 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.13" in namespace kube-system with the configuration for the kubelets in the cluster
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "node1" as an annotation
[mark-control-plane] Marking the node node1 as control-plane by adding the label "node-role.kubernetes.io/master=‘‘"
[mark-control-plane] Marking the node node1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 702gz5.49zhotgsiyqimwqw
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[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

Your Kubernetes master 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

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 192.168.1.57:6443 --token pm5kht.s9fh59lop2m34ge9 --discovery-token-ca-cert-hash sha256:9c0f2cc3ab7c2a4bee0532952600befc0e2faf02794c23fa6227870fef18b18a   --ignore-preflight-errors=Swap

上面记录了完成的初始化输出的内容,根据输出的内容基本上可以看出手动初始化安装一个Kubernetes集群所需要的关键步骤。

其中有以下关键内容:

  • [kubelet-start] 生成kubelet的配置文件”/var/lib/kubelet/config.yaml”
  • [certificates]生成相关的各种证书
  • [kubeconfig]生成相关的kubeconfig文件
  • [bootstraptoken]生成token记录下来,后边使用kubeadm join往集群中添加节点时会用到
  • 下面的命令是配置常规用户如何使用kubectl访问集群:
    mkdir -p $HOME/.kube
    sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
    sudo chown $(id -u):$(id -g) $HOME/.kube/config

    最后给出了将节点加入集群的命令

    kubeadm join 192.168.1.57:6443 --token pm5kht.s9fh59lop2m34ge9 --discovery-token-ca-cert-hash sha256:9c0f2cc3ab7c2a4bee0532952600befc0e2faf02794c23fa6227870fef18b18a --ignore-preflight-errors=Swap

查看一下集群状态:

kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-0               Healthy   {"health": "true"}

确认个组件都处于healthy状态。

集群初始化如果遇到问题,可以使用下面的命令进行清理:

kubeadm reset
ifconfig cni0 down
ip link delete cni0
ifconfig flannel.1 down
ip link delete flannel.1
rm -rf /var/lib/cni/

2.3 安装Pod Network

接下来安装flannel network add-on:

mkdir -p /etc/kubernetes/addons/
cd addons/
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f  kube-flannel.yml

clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

这里注意kube-flannel.yml这个文件里的flannel的镜像是0.10.0,quay.io/coreos/flannel:v0.10.0-amd64

如果Node有多个网卡的话,参考flannel issues 39701,目前需要在kube-flannel.yml中使用--iface参数指定集群主机内网网卡的名称,否则可能会出现dns无法解析。需要将kube-flannel.yml下载到本地,flanneld启动参数加上--iface=<iface-name>

containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.10.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1

使用kubectl get pod --all-namespaces -o wide确保所有的Pod都处于Running状态。

kubectl get pod --all-namespaces -o wide
NAMESPACE       NAME                                            READY   STATUS    RESTARTS   AGE     IP               NODE             NOMINATED NODE   READINESS GATES
default         curl-66959f6557-9dv5g                           1/1     Running   1          6d3h    10.244.0.4       192.168.1.57     <none>           <none>
ingress-nginx   nginx-ingress-controller-79b7dccb-6t2nr         1/1     Running   0          3d3h    10.244.2.15      192.168.1.34   <none>           <none>
ingress-nginx   nginx-ingress-controller-79b7dccb-r7ljd         1/1     Running   0          3d3h    10.244.1.29      192.168.1.33   <none>           <none>
ingress-nginx   nginx-ingress-default-backend-759456dbc-8nrsf   1/1     Running   0          3d3h    10.244.1.28      192.168.1.33   <none>           <none>
kube-system     coredns-5fcfdd4ccd-9bk7q                        1/1     Running   0          6d20h   10.244.0.2       192.168.1.57     <none>           <none>
kube-system     coredns-5fcfdd4ccd-dzw89                        1/1     Running   0          6d20h   10.244.0.3       192.168.1.57     <none>           <none>
kube-system     etcd-192.168.1.57                               1/1     Running   0          6d20h   192.168.1.57   192.168.1.57     <none>           <none>
kube-system     kube-apiserver-192.168.1.57                     1/1     Running   0          6d20h   192.168.1.57   192.168.1.57     <none>           <none>
kube-system     kube-controller-manager-192.168.1.57            1/1     Running   0          6d20h   192.168.1.57   192.168.1.57     <none>           <none>
kube-system     kube-flannel-ds-amd64-226tp                     1/1     Running   0          6d      192.168.1.33   192.168.1.33   <none>           <none>
kube-system     kube-flannel-ds-amd64-7r74j                     1/1     Running   0          6d      192.168.1.34   192.168.1.34   <none>           <none>
kube-system     kube-flannel-ds-amd64-rxzms                     1/1     Running   0          6d3h    192.168.1.57   192.168.1.57     <none>           <none>
kube-system     kube-proxy-5r4mg                                1/1     Running   0          5d23h   192.168.1.34   192.168.1.34   <none>           <none>
kube-system     kube-proxy-82867                                1/1     Running   0          5d23h   192.168.1.33   192.168.1.33   <none>           <none>
kube-system     kube-proxy-hqgkw                                1/1     Running   0          5d23h   192.168.1.57   192.168.1.57     <none>           <none>
kube-system     kube-scheduler-192.168.1.57                     1/1     Running   0          6d20h   192.168.1.57   192.168.1.57     <none>           <none>
kube-system     tiller-deploy-84bcb9978c-2blph                  1/1     Running   0          3d3h    10.244.2.13      192.168.1.34   <none>           <none>

2.4 master node参与工作负载

使用kubeadm初始化的集群,出于安全考虑Pod不会被调度到Master Node上,也就是说Master Node不参与工作负载。这是因为当前的master节点node1被打上了node-role.kubernetes.io/master:NoSchedule的污点:

kubectl describe node node1 | grep Taint
Taints:             node-role.kubernetes.io/master:NoSchedule

因为这里搭建的是测试环境,去掉这个污点使node1参与工作负载:

kubectl taint nodes node1 node-role.kubernetes.io/master-
node "node1" untainted

2.5 测试DNS

kubectl run curl --image=radial/busyboxplus:curl -it
kubectl run --generator=deployment/apps.v1beta1 is DEPRECATED and will be removed in a future version. Use kubectl create instead.
If you don‘t see a command prompt, try pressing enter.
[ [email protected]:/ ]$ 

进入后执行nslookup kubernetes.default确认解析正常:

nslookup kubernetes.default
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes.default
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local

2.6 向Kubernetes集群中添加Node节点

优先级:
/etc/sysconfig/kubelet 参数高于/var/lib/kubelet/config.yaml
这里修改上报节点name为ip,修改kubelet

KUBELET_EXTRA_ARGS=--fail-swap-on=false --hostname-override=192.168.1.33
systemctl daemon-reload
systemctl restart kubelet

下面我们将node2这个主机添加到Kubernetes集群中,因为我们同样在node2上的kubelet的启动参数中去掉了必须关闭swap的限制,所以同样需要--ignore-preflight-errors=Swap这个参数。 在node2上执行:

kubeadm join 192.168.1.57:6443 --token 702gz5.49zhotgsiyqimwqw --discovery-token-ca-cert-hash sha256:2bc50229343849e8021d2aa19d9d314539b40ec7a311b5bb6ca1d3cd10957c2f  --ignore-preflight-errors=Swap

[preflight] Running pre-flight checks
        [WARNING Swap]: running with swap on is not supported. Please disable swap
[discovery] Trying to connect to API Server "192.168.1.57:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.61.11:6443"
[discovery] Requesting info from "https://192.168.1.57:6443" 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 "192.168.1.57:6443"
[discovery] Successfully established connection with API Server "192.168.1.57:6443"
[join] Reading configuration from the cluster...
[join] FYI: You can look at this config file with ‘kubectl -n kube-system get cm kubeadm-config -oyaml‘
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.13" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] 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 "node2" 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.

node2加入集群很是顺利,下面在master节点上执行命令查看集群中的节点:

kubectl get nodes
NAME             STATUS   ROLES    AGE     VERSION
192.168.1.33   Ready    edge     6d      v1.13.1
192.168.1.34   Ready    edge     6d      v1.13.1
192.168.1.57     Ready    master   6d20h   v1.13.1

如何从集群中移除Node
如果需要从集群中移除node2这个Node执行下面的命令:

在master节点上执行:

kubectl drain node2 --delete-local-data --force --ignore-daemonsets
kubectl delete node node2

在node2上执行:

kubeadm reset
ifconfig cni0 down
ip link delete cni0
ifconfig flannel.1 down
ip link delete flannel.1
rm -rf /var/lib/cni/

在master上执行:

kubectl delete node node2

2.7 kube-proxy开启ipvs

修改ConfigMap的kube-system/kube-proxy中的config.conf,mode: "ipvs":

kubectl edit cm kube-proxy -n kube-system

之后重启各个节点上的kube-proxy pod:

kubectl get pod -n kube-system | grep kube-proxy | awk ‘{system("kubectl delete pod "$1" -n kube-system")}‘
kubectl get pod -n kube-system | grep kube-proxy
kube-proxy-pf55q                1/1     Running   0          9s
kube-proxy-qjnnc                1/1     Running   0          14s

kubectl logs kube-proxy-pf55q -n kube-system
I1208 06:12:23.516444       1 server_others.go:189] Using ipvs Proxier.
W1208 06:12:23.516738       1 proxier.go:365] IPVS scheduler not specified, use rr by default
I1208 06:12:23.516840       1 server_others.go:216] Tearing down inactive rules.
I1208 06:12:23.575222       1 server.go:464] Version: v1.13.0
I1208 06:12:23.585142       1 conntrack.go:52] Setting nf_conntrack_max to 131072
I1208 06:12:23.586203       1 config.go:202] Starting service config controller
I1208 06:12:23.586243       1 controller_utils.go:1027] Waiting for caches to sync for service config controller
I1208 06:12:23.586269       1 config.go:102] Starting endpoints config controller
I1208 06:12:23.586275       1 controller_utils.go:1027] Waiting for caches to sync for endpoints config controller
I1208 06:12:23.686959       1 controller_utils.go:1034] Caches are synced for endpoints config controller
I1208 06:12:23.687056       1 controller_utils.go:1034] Caches are synced for service config controller

日志中打印出了Using ipvs Proxier,说明ipvs模式已经开启。

3.Kubernetes常用组件部署

越来越多的公司和团队开始使用Helm这个Kubernetes的包管理器,我们也将使用Helm安装Kubernetes的常用组件。

3.1 Helm的安装

Helm由客户端命helm令行工具和服务端tiller组成,Helm的安装十分简单。 下载helm命令行工具到master节点node1的/usr/local/bin下,这里下载的2.12.0版本:

wget https://storage.googleapis.com/kubernetes-helm/helm-v2.12.0-linux-amd64.tar.gz
tar -zxvf helm-v2.12.0-linux-amd64.tar.gz
cd linux-amd64/
cp helm /usr/local/bin/

因为Kubernetes APIServer开启了RBAC访问控制,所以需要创建tiller使用的service account: tiller并分配合适的角色给它。 详细内容可以查看helm文档中的Role-based Access Control。 这里简单起见直接分配cluster-admin这个集群内置的ClusterRole给它。创建rbac-config.yaml文件:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: tiller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: tiller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: tiller
    namespace: kube-system
kubectl create -f rbac-config.yaml
serviceaccount/tiller created
clusterrolebinding.rbac.authorization.k8s.io/tiller created

接下来使用helm部署tiller:
使用阿里云镜像,并指定repo为阿里云

helm init --upgrade -i registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:v2.12.0 --stable-repo-url https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts

tiller默认被部署在k8s集群中的kube-system这个namespace下:

kubectl get pod -n kube-system -l app=helm
NAME                            READY   STATUS    RESTARTS   AGE
tiller-deploy-c4fd4cd68-dwkhv   1/1     Running   0          83s
helm version
Client: &version.Version{SemVer:"v2.12.0", GitCommit:"d325d2a9c179b33af1a024cdb5a4472b6288016a", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.12.0", GitCommit:"d325d2a9c179b33af1a024cdb5a4472b6288016a", GitTreeState:"clean"}

注意由于某些原因需要网络可以访问gcr.io和kubernetes-charts.storage.googleapis.com,如果无法访问可以通过helm init --service-account tiller --tiller-image <your-docker-registry>/tiller:v2.11.0 --skip-refresh使用私有镜像仓库中的tiller镜像

3.2 使用Helm部署Nginx Ingress

为了便于将集群中的服务暴露到集群外部,从集群外部访问,接下来使用Helm将Nginx Ingress部署到Kubernetes上。 Nginx Ingress Controller被部署在Kubernetes的边缘节点上,关于Kubernetes边缘节点的高可用相关的内容可以查看我前面整理的Bare metal环境下Kubernetes Ingress边缘节点的高可用(基于IPVS)。

我们将node1(192.168.1.33)和node2(192.168.1.34)同时做为边缘节点,打上Label:

kubectl label node 192.168.1.33 node-role.kubernetes.io/edge=
node/node1 labeled

kubectl label node 192.168.1.34 node-role.kubernetes.io/edge=
node/node2 labeled

kubectl get node
NAME             STATUS   ROLES    AGE     VERSION
192.168.1.33   Ready    edge     6d      v1.13.1
192.168.1.34   Ready    edge     6d      v1.13.1
192.168.1.57     Ready    master   6d20h   v1.13.1

stable/nginx-ingress chart的值文件ingress-nginx.yaml:

controller:
  replicaCount: 2
  service:
    externalIPs:
      - 192.168.1.68
  nodeSelector:
    node-role.kubernetes.io/edge: ‘‘
  affinity:
    podAntiAffinity:
        requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchExpressions:
            - key: app 
              operator: In
              values:
              - nginx-ingress
            - key: component
              operator: In
              values:
              - controller
          topologyKey: kubernetes.io/hostname
  tolerations:
      - key: node-role.kubernetes.io/master
        operator: Exists
        effect: NoSchedule

defaultBackend:
  nodeSelector:
    node-role.kubernetes.io/edge: ‘‘
  tolerations:
      - key: node-role.kubernetes.io/master
        operator: Exists
        effect: NoSchedule

nginx ingress controller的副本数replicaCount为2,将被调度到node1和node2这两个边缘节点上。externalIPs指定的192.168.1.68为VIP,将绑定到kube-proxy kube-ipvs0网卡上。

helm install stable/nginx-ingress -n nginx-ingress --namespace ingress-nginx  -f ingress-nginx.yaml --set rbac.create=true
kubectl get pod -n ingress-nginx -o wide
NAME                                            READY   STATUS    RESTARTS   AGE    IP            NODE             NOMINATED NODE   READINESS GATES
nginx-ingress-controller-79b7dccb-6t2nr         1/1     Running   0          3d3h   10.244.2.15   192.168.1.34   <none>           <none>
nginx-ingress-controller-79b7dccb-r7ljd         1/1     Running   0          3d3h   10.244.1.29   192.168.1.33   <none>           <none>
nginx-ingress-default-backend-759456dbc-8nrsf   1/1     Running   0          3d3h   10.244.1.28   192.168.1.33   <none>           <none>

如果访问http://192.168.1.68返回default backend,则部署完成。

注意:这里的VIP68,只能从k8s集群的node才能访问。

实际测试的结果是无法访问,于是怀疑kube-proxy出了问题,查看kube-proxy的日志,不停的刷下面的log:

I1224 02:46:27.793377       1 graceful_termination.go:160] Trying to delete rs: 10.103.201.140:44134/TCP/10.244.1.25:44134
I1224 02:46:27.793539       1 graceful_termination.go:173] Deleting rs: 10.103.201.140:44134/TCP/10.244.1.25:44134

在Kubernetes的Github上找到了这个ISSUE https://github.com/kubernetes/kubernetes/issues/71071,大致是最近更新的IPVS proxier mode now support connection based graceful termination.引入了bug,导致Kubernetes的1.11.5、1.12.1~1.12.3、1.13.0都有这个问题,即kube-proxy在ipvs模式下不可用。而官方称在1.11.5、1.12.3、1.13.0中修复了12月4日k8s的特权升级漏洞(CVE-2018-1002105),如果针对这个漏洞做k8s升级的同学,需要小心,确认是否开启了ipvs,避免由升级引起k8s网络问题。由于我们线上的版本是1.11并且已经启用了ipvs,所以这里我们只能先把线上master node升级到了1.11.5,而kube-proxy还在使用1.11.4的版本。

https://github.com/kubernetes/kubernetes/issues/71071中已经描述有相关PR解决这个问题,后续只能跟踪一下1.11.5、1.12.3、1.13.0之后的小版本了

查看kube-proxy日志,https://github.com/kubernetes/kubernetes/issues/71071的问题依旧

以上是关于kubeadm1.13安装的主要内容,如果未能解决你的问题,请参考以下文章

PHP代码-psysh调试代码片段工具

VIM 代码片段插件 ultisnips 使用教程

Android 插件化VirtualApp 源码分析 ( 目前的 API 现状 | 安装应用源码分析 | 安装按钮执行的操作 | 返回到 HomeActivity 执行的操作 )(代码片段

nodejs常用代码片段

vim代码片段插件ultisnips的使用

续:纠正:ubuntu7.04可以安装,而且完美的安装 ! for《Oracle-10.2.0.1,打补丁10.2.0.5:在 debian 版本4不含4以上,及 ubuntu 7.04不含(代码片段