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在谷歌云上自建 K8s 集群并使用 VPC Native 方式实现容器网络互通

2021-08-20    云上马可君
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概述

谷歌云使用先进的 Andromeda 网络来实现 VPC 内实例之间的相互访问,以及 google Kubernetes Engine (GKE) 的 Pod 的跨节点互访,避免了配置静态路由或者 Overlay 网络带来的运维复杂度以及性能瓶颈。使用谷歌云的 VPC Native(使用 IP Alias 而非静态路由)方式来实现 Pod 间网络通讯的集群称作为 VPC 原生(VPC Native)集群。VPC 原生集群具有以下优势。

这些先进的网络功能,也可以提供给用户在谷歌云虚机实例上自建的 Kubernetes 集群来使用。本文介绍了相关的配置和测试方法。

一 创建 VPC

1 创建 VPC

首先创建 VPC:

gcloud compute networks create   k8s-vpc
      --subnet-mode=custom
      --bgp-routing-mode=global
      --mtu=1500


2 创建 VPC 防火墙规则

在 VPC 中添加防火墙规则:

gcloud compute firewall-rules   create k8s-vpc-default-firewall

    --network k8s-vpc --allow tcp:22,tcp:80,tcp:3389,icmp
 
  gcloud compute firewall-rules create k8s-vpc-k8s-firewall

    --network k8s-vpc

    --allow   tcp:6443,tcp:2379-2380,tcp:10250-10252,tcp:30000-32767

3 创建子网

创建子网 asia-southeast1-sub-1。为其规划如下网段。

gcloud compute networks subnets   create asia-southeast1-sub-1
      --network=k8s-vpc
      --range=10.122.16.0/21
      --region=asia-southeast1

给子网配置从属网段

gcloud compute networks subnets   update asia-southeast1-sub-1
    --region=asia-southeast1
      --add-secondary-ranges=asia-southeast1-sub-1-pod=192.168.16.0/21
 
  gcloud compute networks subnets update asia-southeast1-sub-1
    --region=asia-southeast1
    --add-secondary-ranges=asia-southeast1-sub-1-svc=172.16.16.0/21

二 创建虚拟机

1 创建 K8s 集群的 Master 和 Node 虚机。

每个 Node 会有一个由 Master 自动分配的 Pod CIDR,需要根据这个网段来配置每个 Node 虚机实例的 Alias IP Range,本例分配的情况如下。

注意打开 IP Forward 并配置 Alias IP 网段给 Pod 使用。

 

A Master

注意 Master 需要绑定一个有权限创建负载均衡的 Service Account,以及谷歌云 API 调用范围,否则,创建 Kubernetes 的 Service 时自动创建谷歌云负载均衡会失败。

gcloud   compute instances create kub-m

  --project=youzhi-lab

  --zone=asia-southeast1-b

  --machine-type=n2-standard-2

  --network-interface=network-tier=PREMIUM,subnet=asia-southeast1-sub-1  

  --can-ip-forward

  --maintenance-policy=MIGRATE

  --image=centos-7-v20210721

  --image-project=centos-cloud

  --boot-disk-size=100GB

  --no-boot-disk-auto-delete

  --boot-disk-type=pd-balanced

  --boot-disk-device-name=kub-m

  --no-shielded-secure-boot

  --shielded-vtpm

  --shielded-integrity-monitoring

  --reservation-affinity=any

    --service-account=247839977271-compute@developer.gserviceaccount.com

  --scopes=https://www.googleapis.com/auth/cloud-platform


B Node-1

gcloud   compute instances create kub-n-1
    --project=youzhi-lab
    --zone=asia-southeast1-b
    --machine-type=n2-standard-4
      --network-interface=network-tier=PREMIUM,subnet=asia-southeast1-sub-1  
    --can-ip-forward
    --maintenance-policy=MIGRATE
    --image=centos-7-v20210721
    --image-project=centos-cloud
    --boot-disk-size=100GB
    --no-boot-disk-auto-delete
    --boot-disk-type=pd-balanced
    --boot-disk-device-name=kub-n-1
    --no-shielded-secure-boot
    --shielded-vtpm
    --shielded-integrity-monitoring
    --reservation-affinity=any


C Node-2

gcloud   compute instances create kub-n-2
    --project=youzhi-lab
    --zone=asia-southeast1-b
    --machine-type=n2-standard-4
      --network-interface=network-tier=PREMIUM,subnet=asia-southeast1-sub-1  
    --can-ip-forward
    --maintenance-policy=MIGRATE
    --image=centos-7-v20210721
    --image-project=centos-cloud
    --boot-disk-size=100GB
    --no-boot-disk-auto-delete
    --boot-disk-type=pd-balanced
    --boot-disk-device-name=kub-n-2
    --no-shielded-secure-boot
    --shielded-vtpm
    --shielded-integrity-monitoring
    --reservation-affinity=any

 

2 安装 Docker

在所有的 VM 上安装 Docker:

sudo   yum install -y yum-utils
  sudo yum-config-manager
      --add-repo
        https://download.docker.com/linux/centos/docker-ce.repo
  sudo yum install docker-ce docker-ce-cli containerd.io
  sudo systemctl start docker
  sudo docker run hello-world
  sudo mkdir /etc/docker
  cat <<EOF | sudo tee /etc/docker/daemon.json
  {
    "exec-opts": ["native.cgroupdriver=systemd"],
    "log-driver": "json-file",
    "log-opts": {
      "max-size": "100m"
    },
    "storage-driver": "overlay2"
  }
  EOF
 
  sudo systemctl enable   docker
  sudo systemctl daemon-reload
  sudo systemctl restart docker

 

3 安装 kubeadm 及其工具

系统设置,以及工具安装:

sudo   systemctl stop firewalld.service
  sudo systemctl disable   firewalld.service
  sudo modprobe br_netfilter
 
  cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
  br_netfilter
  EOF
 
  cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
  net.bridge.bridge-nf-call-ip6tables = 1
  net.bridge.bridge-nf-call-iptables = 1
  EOF
  sudo sysctl --system
 
  cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
  [kubernetes]
  name=Kubernetes
  baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-$basearch
  enabled=1
  gpgcheck=1
  repo_gpgcheck=1
  gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg   https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
  exclude=kubelet kubeadm kubectl
  EOF
 
  # Set SELinux   in permissive mode (effectively disabling it)
  sudo setenforce 0
  sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
 
  sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
 
  sudo systemctl enable   --now kubelet

 

配置 kubeadm 初始化参数

cat <<EOF | sudo tee sudo   /proc/sys/net/ipv4/ip_forward
  1
  EOF

4 关闭 IP Alias 的 local route table

在 GCE 中,GCE agent 的 network Daemon 会监控 IP Alias 地址,并添加相应的路由。但在这种情况下,会造成 container 通讯的故障。通过下面的命令在 Master 和各个 Node 系统内修改 GCE agent 配置,并重启 google guest agent 服务。目的是 Pod 通过 Alias IP 地址互访时,不通过虚机实例的 Nat,而访问其他地址时,采用 NAT 的方式。


sudo sed -i 's/ip_aliases =   true/ip_aliases = false/'

     /etc/default/instance_configs.cfg

 

sudo systemctl restart   google-guest-agent

iptables -P FORWARD ACCEPT

 

ip route show table local  #查看本地路由表, 确保alias IP段没有在eth0上


三 通过 kubeadm 安装 kubernetes

1 安装配置 Master 节点

A 配置 Master 节点

export name="$(hostname)"
  export pod_cidr="192.168.16.0/21"
  export   service_cidr="172.16.16.0/21"
  cat <<EOF > /tmp/kubeadm-config.yaml
  apiVersion: kubeadm.k8s.io/v1beta3
  kind: InitConfiguration
  bootstrapTokens:
  - groups:
    -   system:bootstrAppers:kubeadm:default-node-token
    token: youzhi.0123456789abcdef
  nodeRegistration:
    name: $name
    kubeletExtraArgs:
      cloud-provider: gce
      network-plugin: kubenet
      non-masquerade-cidr: 0.0.0.0/0
  ---
  apiVersion: kubeadm.k8s.io/v1beta3
  kind: ClusterConfiguration
  networking:
    podSubnet: ${pod_cidr}
    serviceSubnet: ${service_cidr}
  apiServer:
    extraArgs:
      enable-admission-plugins:   DefaultStorageClass,NodeRestriction
      cloud-provider: gce
  controllerManager:
    extraArgs:
      cloud-provider: gce

    configure-cloud-routes: "false"
      address: 0.0.0.0
  EOF


B 通过配置文件安装

sudo kubeadm init
    --config=/tmp/kubeadm-config.yaml

如果执行成功,会有以下输出。

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:
 
  sudo kubeadm join 10.122.16.10:6443 --token youzhi.0123456789abcdef
    --discovery-token-ca-cert-hash   sha256:e5c96b2d0499287b6884c27b8ec7293e6aab1ab09540a0386b91ecbadfb38d4f


C 配置 kubectl 配置文件

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

D 安装 ip-masq-agent

默认配置下, Pod-Pod 访问时会进行 SNAT。使用 Alias IP 方式直接路由方式时,可以通过部署 ip-masq-agent 的方式关闭 SNAT。

$ kubectl apply -f   https://raw.githubusercontent.com/kubernetes-sigs/ip-masq-agent/master/ip-masq-agent.yaml

2 安装配置 Node

A Join

在两个 Node 节点上运行 join 命令:

sudo kubeadm join   10.122.16.10:6443 --token youzhi.0123456789abcdef
    --discovery-token-ca-cert-hash sha256:e5c96b2d0499287b6884c27b8ec7293e6aab1ab09540a0386b91ecbadfb38d4f

B 查看 Node 状态

此时 Node 是 NotReady 状态,因为 kubelet 的网络插件配置有问题。

$ kubectl get node
  NAME      STATUS     ROLES                  AGE    VERSION
  kub-m     Ready      control-plane,master   137m     v1.22.0
  kub-n-1   NotReady   <none>                 15m    v1.22.0

C 修改 Node 上 kubelet 配置

 

这时 node 的状态变成 Ready:

$ kubectl get node
  NAME      STATUS   ROLES                  AGE    VERSION
  kub-m     Ready    control-plane,master   147m     v1.22.0
  kub-n-1   Ready    <none>                 25m    v1.22.0


D 修改 Node providerID

为了 Service 能自动创建和配置谷歌云负载均衡,需要配置每个 Node 的 providerID 参数。对于谷歌云上的 Node,providerID 的格式是 gce://<Project ID>/<Zone>/<Instance Name>。

在 Master 节点,运行 kubectl 修改每个 Node 的 prividerID:


$ kubectl patch node kub-n-1

    -p '{"spec":{"providerID":"gce://youzhi-lab/asia-southeast1-b/kub-n-1"}}'
  node/kub-n-1 patched
  $ kubectl patch node kub-n-2

    -p '{"spec":{"providerID":"gce://youzhi-lab/asia-southeast1-b/kub-n-2"}}'
  node/kub-n-2 patched


E 给 GCE 添加 Network Tag

在 Kubernetes 通过 cloud-provider 创建实现 Service 的谷歌云负载均衡的时候,需要通过 network tag 创建 firewall rules。所以需要给 GCE 实例添加 network tag。创建的规则是所有 node 相同的前缀,比如这里两台 VM 相同的前缀是 kub-n


gcloud compute instances   add-tags kub-n-1

    --zone asia-southeast1-b --tags kub-n
  gcloud compute instances add-tags kub-n-2

    --zone asia-southeast1-b --tags kub-n


F 给 Node 虚机实例添加 Alias IP

kubectl get nodes 列出各个 Node 的名称。

查看每个 Node 的 Pod CIDR,如下。

$ kubectl get node kub-n-1 -o   jsonpath={.spec.podCIDR}
  192.168.18.0/24

使用谷歌云命令行工具,根据上面的打印结果,分别更新各个 Node 的 Alias IP,使其与该 Node 的 Pod CIDR 一致。

● Node-1

gcloud compute instances   network-interfaces update kub-n-1
      --zone asia-southeast1-b
      --aliases   "asia-southeast1-sub-1-pod:192.168.17.0/24"


● Node-2

gcloud compute instances   network-interfaces update kub-n-2
      --zone asia-southeast1-b
      --aliases   "asia-southeast1-sub-1-pod:192.168.18.0/24"

3 检测配置

A 创建 deployment 和 service


kubectl create deploy Nginx   --image nginx
  kubectl scale deploy/nginx --replicas=6

kubectl expose deployment nginx  

    --port 80 --target-port 80 --name nginx-lb --type LoadBalancer


B 查看部署情况查看 pod 情况:

$   kubectl get pod -o wide

NAME                     READY   STATUS      RESTARTS   AGE   IP              NODE  

nginx-6799fc88d8-68fld   1/1       Running   0          17h   192.168.18.7    kub-n-2

nginx-6799fc88d8-gssw5   1/1       Running   0          17h   192.168.17.15   kub-n-1

nginx-6799fc88d8-jcdhc   1/1       Running   0          17h   192.168.17.14   kub-n-1

nginx-6799fc88d8-k7sxg   1/1       Running   0          17h   192.168.18.6    kub-n-2

nginx-6799fc88d8-l6nnv   1/1       Running   0          17h   192.168.18.5    kub-n-2

nginx-6799fc88d8-tcbmf   1/1       Running   0          17h   192.168.17.13   kub-n-1

查看 Service:

$   kubectl get svc
  NAME         TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)        AGE

kubernetes   ClusterIP      172.16.16.1     <none>          443/TCP        29h

nginx-lb     LoadBalancer   172.16.16.153   34.126.129.75   80:32761/TCP   7m31s

获取 Service 的 LB IP

ip=$(kubectl get svc -l   app=nginx

    -o jsonpath={.items[0].status.loadBalancer.ingress[0].ip})

测试 Pod 的同 Node 和跨 Node 访问

$ kubectl exec -it nginx-6799fc88d8-68fld bash
  kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future   version. Use kubectl exec [POD] -- [COMMAND] instead.
  root@nginx-6799fc88d8-68fld:/# curl -I 192.168.18.6
  HTTP/1.1 200 OK
  Server: nginx/1.21.1
  Date: Thu, 12 Aug 2021 07:25:29 GMT
  Content-Type: text/html
  Content-Length: 612
  Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
  Connection: keep-alive
  ETag: "60e46fc5-264"
  Accept-Ranges: bytes
 
  root@nginx-6799fc88d8-68fld:/# curl -I 192.168.17.15
  HTTP/1.1 200 OK
  Server: nginx/1.21.1
  Date: Thu, 12 Aug 2021 07:25:35 GMT
  Content-Type: text/html
  Content-Length: 612
  Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
  Connection: keep-alive
  ETag: "60e46fc5-264"
  Accept-Ranges: bytes

测试通过 Cluser IP 访问 Service

root@nginx-6799fc88d8-68fld:/# curl   -I 172.16.16.153
  HTTP/1.1 200 OK
  Server: nginx/1.21.1
  Date: Thu, 12 Aug 2021 07:25:43 GMT
  Content-Type: text/html
  Content-Length: 612
  Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
  Connection: keep-alive
  ETag: "60e46fc5-264"
  Accept-Ranges: bytes

测试 Service 从公网访问:

$ curl -I $ip
  HTTP/1.1 200 OK
  Server: nginx/1.21.1
  Date: Wed, 11 Aug 2021 14:25:06 GMT
  Content-Type: text/html
  Content-Length: 612
  Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
  Connection: keep-alive
  ETag: "60e46fc5-264"
  Accept-Ranges: bytes

C 测试从其它子网访问 Pod

现在集群上的 Pod 除了可以同一子网内互相访问,也可以让 VPC 下其它子网(同一区域或者不同区域都可以)以及通过专线或 VPN 与本 VPC 互通的线下机房网络里的虚机来访问。下面在不同区域创建一个新子网,以及该子网下的虚机,来访问集群上的 Pod。

gcloud compute networks subnets create us-central1-sub-1
--network=k8s-vpc
--range=10.150.16.0/21
--region=us-central1
gcloud compute instances create remote-test-1 --project=youzhi-lab --zone=us-central1-b --machine-type=n2-standard-4 --network-interface=network-tier=PREMIUM,subnet=us-central1-sub-1 --can-ip-forward --maintenance-policy=MIGRATE --image=centos-7-v20210721 --image-project=centos-cloud --boot-disk-size=100GB --no-boot-disk-auto-delete --boot-disk-type=pd-balanced --boot-disk-device-name=remote-test-1 --no-shielded-secure-boot --shielded-vtpm --shielded-integrity-monitoring --reservation-affinity=any

登录 remote-test1 虚机,并运行以下命令访问 Pod。

$ curl -I 192.168.18.7
HTTP/1.1 200 OK
Server: nginx/1.21.1
Date: Fri, 13 Aug 2021 05:35:46 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
Connection: keep-alive
ETag: "60e46fc5-264"
Accept-Ranges: bytes
$ curl -I 192.168.17.14
HTTP/1.1 200 OK
Server: nginx/1.21.1
Date: Fri, 13 Aug 2021 05:36:00 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 06 Jul 2021 14:59:17 GMT
Connection: keep-alive
ETag: "60e46fc5-264"
Accept-Ranges: bytes

可以确认访问成功。

 

D 确认 Node 上关闭 Pod 访问 SNAT

如果检测结果与下面的结果有差异,确认执行 Master 节点配置的“安装 ip-masq-agent”一节。

$ kubectl get ds -n kube-system
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE
ip-masq-agent 2 2 2 2 2 <none> 19m
kube-proxy 3 3 3 3 3 kubernetes.io/os=linux 29h

在每台 Node 上查看 NAT, IP-MASQ-AGENT Chain 默认会针对目的地址为 RFC1918 地址段不做地址翻译。

$ sudo iptables -t nat -L -n --line-numbers
Chain POSTROUTING (policy ACCEPT)
num target prot opt source destination
1 KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */
2 IP-MASQ-AGENT all -- 0.0.0.0/0 0.0.0.0/0 /* ip-masq-agent: ensure nat POSTROUTING directs all non-LOCAL destination traffic t
o our custom IP-MASQ-AGENT chain */ ADDRTYPE match dst-type !LOCAL
Chain IP-MASQ-AGENT (1 references)
num target prot opt source destination
1 RETURN all -- 0.0.0.0/0 169.254.0.0/16 /* ip-masq-agent: cluster-local traffic should not be subject to MASQUERADE */ ADDRTYPE
match dst-type !LOCAL
2 RETURN all -- 0.0.0.0/0 10.0.0.0/8 /* ip-masq-agent: cluster-local traffic should not be subject to MASQUERADE */ ADDRTYPE
match dst-type !LOCAL
3 RETURN all -- 0.0.0.0/0 172.16.0.0/12 /* ip-masq-agent: cluster-local traffic should not be subject to MASQUERADE */ ADDRTYPE
match dst-type !LOCAL
4 RETURN all -- 0.0.0.0/0 192.168.0.0/16 /* ip-masq-agent: cluster-local traffic should not be subject to MASQUERADE */ ADDRTYPE
match dst-type !LOCAL
5 MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* ip-masq-agent: outbound traffic should be subject to MASQUERADE (this match must com
e after cluster-local CIDR matches) */ ADDRTYPE match dst-type !LOCAL

 

四 总结

在 GCE 上通过 kubeadm 可以非常方便的安装 kubernetes 集群,通过 GCP VPC 的各种网络功能,配合 Kubernetes 本身 cloud-provider 的功能,可以非常方便的实现 Kubernetes 网络的各种功能。

Appendix


1 kubeadm 创建 token

kubeadm token create --ttl=0 --print-join-command
kubeadm join 10.128.1.96:6443

--token xxxx

--discovery-token-ca-cert-hash sha256:xxxx

 

2 alias IP 模式下的配置

确认删除 Alias IP 的本地路由:

https://cloud.google.com/vpc/docs/configure-alias-ip-ranges#enabling_ip_alias_on_images_disables_cbr0_bridge_on_self-managed_kubernetes_clusters

通过 GCP Alias IP 实现跨 Node 的 Pod 互通

3 K8s 网络针对 GCP 的配置注意事项

https://kubernetes.io/docs/concepts/cluster-administration/networking/#google-compute-engine-gce


4 Node, Pod 和 Service 网段配置参考表

https://cloud.google.com/kubernetes-engine/docs/concepts/alias-ips#cluster_sizing_secondary_range_pods


5 Kubadmin 安装步骤

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/


Kubeadmin init 参数

https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-init/


Ip-masq-agent 部署

https://kubernetes.io/docs/tasks/administer-cluster/ip-masq-agent/

 

 

 

转载自:
https://gcp.infoq.cn/article.html?id=197373f7-464e-4c9f-b894-365e7883d3e6

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