kubeadm1.13安装
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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。
查看kube-proxy日志,https://github.com/kubernetes/kubernetes/issues/71071的问题依旧。
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