kubeadm を用いた簡単なkubernetes環境構成
kubernetesを手軽に構築しよう
記事は移してきたものなので、最新バージョンではないですが、現在のバージョン(1.18.0)でも使用可能です。
環境
Master ×1 (CentOS 7, 2 vCPU, 2 GB or more of RAM)
kubemaster1.mydom.local
Worker × 2 (CentOS 7, 2 vCPU, 2 GB or more of RAM)
kubeworker1.mydom.local
kubeworker2.mydom.local
事前準備
kubeadmをインストールするのに必要な準備をしていきます。
hosts設定及びhosts.listの作成
hostファイルにサーバー情報を書き、for分ようにhosts.listを作成します。
# vi /etc/hosts 192.168.1.20 kubemaster1.mydom.local kubemaster 192.168.1.21 kubeworker1.mydom.local kubeworker1 192.168.1.22 kubeworker2.mydom.local kubeworker2 # cat /etc/hosts | grep "192.168" | awk -F' ' '{print $2}' > /root/hosts.list
Selinux無効化
# for i in `cat hosts.list`; do ssh $i "sed -i 's/=enforcing/=disabled/' /etc/selinux/config"; done
firewall無効化
# for i in `cat hosts.list`; do ssh $i "systemctl stop firewalld; systemctl disable firewalld"; done
IPv6の無効化
# for i in `cat hosts.list`; do ssh $i 'sed -i "s/GRUB_CMDLINE_LINUX=\"/GRUB_CMDLINE_LINUX=\"ipv6.disable=1 transparent_hugepage=never /" /etc/default/grub; grub2-mkconfig -o /boot/grub2/grub.cfg'; done
vm.swappness設定
# for i in `cat hosts.list`; do ssh $i 'echo "vm.swappiness=1" >> /etc/sysctl.conf'; done
SSH設定
ここは、少し手抜きです。
# ssh-keygen # cd ./.ssh/ # cat id_rsa.pub >> authorized_keys # chmod 600 ~/.ssh/authorized_keys # scp -rp .ssh root@kubeworker1.mydom.local:~/ # scp -rp .ssh root@kubeworker2.mydom.local:~/
hosts fileの送付
# scp -p /etc/hosts root@kubeworker1.mydom.local:/etc/hosts # scp -p /etc/hosts root@kubeworker2.mydom.local:/etc/hosts
その他
localrepo, http, ntpの設定を必要に応じて実施します。
Containerdのインストール(Master node上での実施)
準備
以下を順に実施します。
# yum install -y yum-utils # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y yum-utils'; done # yum install -y device-mapper-persistent-data # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y device-mapper-persistent-data'; done # yum install -y lvm2 # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y lvm2'; done # yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo'; done # for i in $(cat /root/hosts.list); do ssh $i 'yum clean all' ssh $i 'yum repolist' done # for i in $(cat hosts.list); do ssh $i 'yum update -y'; done # yum install -y container-selinux # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y container-selinux'; done # yum install -y docker-ce-18.09.6-3.el7.x86_64 docker-ce-cli-18.09.6-3.el7.x86_64 containerd. # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y docker-ce-18.09.6-3.el7.x86_64 docker-ce-cli-18.09.6-3.el7.x86_64 containerd.'; done # mkdir /etc/docker # for i in $(cat hosts.list | sed 1d); do ssh $i 'mkdir /etc/docker'; done # cat > /etc/docker/daemon.json <<EOF { "exec-opts": ["native.cgroupdriver=systemd"], "log-driver": "json-file", "log-opts": { "max-size": "100m" }, "storage-driver": "overlay2", "storage-opts": [ "overlay2.override_kernel_check=true" ] } EOF
dockerの起動
dockerを起動していきます。
# mkdir -p /etc/systemd/system/docker.service.d # for i in $(cat hosts.list | sed 1d); do ssh $i 'mkdir -p /etc/systemd/system/docker.service.d'; done # systemctl daemon-reload # for i in $(cat hosts.list | sed 1d); do ssh $i 'systemctl daemon-reload'; done # systemctl enable docker; systemctl start docker # for i in $(cat hosts.list | sed 1d); do ssh $i 'systemctl enable docker; systemctl start docker'; done # systemctl status docker ● docker.service - Docker Application Container Engine Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled) Active: active (running) since 日 2019-07-14 01:50:22 JST; 1min 13s ago Docs: https://docs.docker.com Main PID: 19164 (dockerd) Tasks: 11 Memory: 29.0M CGroup: /system.slice/docker.service mq19164 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.317228884+09:00" level=info msg="pickfirstBalancer: HandleSubConnStateCh...ule=grpc 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.318563845+09:00" level=warning msg="Using pre-4.0.0 kernel for overlay2,...overlay2 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.337250856+09:00" level=info msg="Graph migration to content-addressabili...seconds" 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.338023813+09:00" level=info msg="Loading containers: start." 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.553369544+09:00" level=info msg="Default bridge (docker0) is assigned wi...address" 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.597964337+09:00" level=info msg="Loading containers: done." 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.621984713+09:00" level=info msg="Docker daemon" commit=481bc77 graphdriv...=18.09.6 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.622089589+09:00" level=info msg="Daemon has completed initialization" 7月 14 01:50:22 kubemaster1.mydom.local dockerd[19164]: time="2019-07-14T01:50:22.630930072+09:00" level=info msg="API listen on /var/run/docker.sock" 7月 14 01:50:22 kubemaster1.mydom.local systemd[1]: Started Docker Application Container Engine. Hint: Some lines were ellipsized, use -l to show in full.
Kubernetesインストール
準備(前Nodeで実施)
# cat >> EOF < /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64 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=kube* EOF # yum clean all # yum repolist
yum repolistにおいて、kubernetesの数が0の場合、kubernetes.repoにsslverify=0を追加します。
再度、yum repolistを個々に実施します。
以下のように質問が来ますので、yを返します。
Loading mirror speeds from cached hostfile * base: mirrors.vcea.wsu.edu * extras: centos.mirror.ndchost.com * updates: mirror.team-cymru.com kubernetes/signature | 454 B 00:00:00 https://packages.cloud.google.com/yum/doc/yum-key.gpg から鍵を取得中です。 Importing GPG key 0xA7317B0F: Userid : "Google Cloud Packages Automatic Signing Key <gc-team@google.com>" Fingerprint: d0bc 747f d8ca f711 7500 d6fa 3746 c208 a731 7b0f From : https://packages.cloud.google.com/yum/doc/yum-key.gpg 上記の処理を行います。よろしいでしょうか？ [y/N]y https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg から鍵を取得中です。 kubernetes/signature | 1.4 kB 00:00:07 !!! kubernetes/primary | 52 kB 00:00:02 kubernetes
kubernetesのインストール
以下をmaster nodeにて実施します。
# yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes # for i in $(cat hosts.list | sed 1d); do ssh $i 'yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes'; done # for i in $(cat hosts.list); do ssh $i 'docker info | grep Cgroup'; done # for i in $(cat hosts.list); do ssh $i 'mkdir /var/lib/kubelet'; done
次に以下を全ノードで実施します。
# cat >> EOF < /var/lib/kubelet/config.yaml kind: KubeletConfiguration apiVersion: kubelet.config.k8s.io/v1beta1 cgroupDriver: \"systemd\" EOF
以下をmaster nodeにて実施します。
# for i in $(cat hosts.list); do ssh $i 'mkdir /etc/systemd/system/kubelet.service.d'; done
次に以下を全ノードで実施します。
# cat >> EOF < /etc/systemd/system/kubelet.service.d/20-extra-args.conf [Service] Environment="KUBELET_EXTRA_ARGS=--fail-swap-on=false" EOF
以下をmaster nodeにて実施します。
# for i in $(cat hosts.list); do ssh $i 'systemctl enable kubelet'; done # for i in $(cat hosts.list); do ssh $i 'systemctl daemon-reload'; done
Master Nodeの構築
ここから、Master Nodeの構築をしていきます。
Initialize
kubeadmを初期化していきます。
# for i in `cat hosts.list`; do ssh $i 'swapoff -a'; done # kubeadm init --pod-network-cidr=10.244.0.0/16 [init] Using Kubernetes version: v1.15.0 [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' [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 "front-proxy-ca" certificate and key [certs] Generating "front-proxy-client" certificate and key [certs] Generating "ca" certificate and key [certs] Generating "apiserver" certificate and key [certs] apiserver serving cert is signed for DNS names [kubemaster1.mydom.local kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.1.20] [certs] Generating "apiserver-kubelet-client" certificate and key [certs] Generating "etcd/ca" certificate and key [certs] Generating "etcd/server" certificate and key [certs] etcd/server serving cert is signed for DNS names [kubemaster1.mydom.local localhost] and IPs [192.168.1.20 127.0.0.1 ::1] [certs] Generating "etcd/peer" certificate and key [certs] etcd/peer serving cert is signed for DNS names [kubemaster1.mydom.local localhost] and IPs [192.168.1.20 127.0.0.1 ::1] [certs] Generating "etcd/healthcheck-client" certificate and key [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 18.003966 seconds [upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace [kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster [upload-certs] Skipping phase. Please see --upload-certs [mark-control-plane] Marking the node kubemaster1.mydom.local as control-plane by adding the label "node-role.kubernetes.io/master=''" [mark-control-plane] Marking the node kubemaster1.mydom.local as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule] [bootstrap-token] Using token: owmrsk.d41wmnxetwhr2hsd [bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials [bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token [bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster [bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace [addons] Applied essential addon: CoreDNS [addons] Applied essential addon: kube-proxy 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 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 192.168.1.20:6443 --token owmrsk.d41wmnxetwhr2hsd \ --discovery-token-ca-cert-hash sha256:35e654eeeb9c125eaee57b12202aa0139729a8cd6209ef77a719c8977dc12905
次にkubectlを使えるようにしていきます。
公式ページなどを参照して、kubectlが叩けるとことまで設定をしてください。
その後、kube-apiserverと疎通が取れるようにしていきます。
# mkdir -p $HOME/.kube # cp -i /etc/kubernetes/admin.conf $HOME/.kube/config # chown $(id -u):$(id -g) $HOME/.kube/config # kubectl cluster-info # kubectl get nodes NAME STATUS ROLES AGE VERSION kubemaster1.mydom.local NotReady master 16m v1.15.0
この時、StatusはNotReadyのままで大丈夫です。
CNIの構築
CNIとしてflannelを構築していきます。
# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml podsecuritypolicy.policy/psp.flannel.unprivileged created clusterrole.rbac.authorization.k8s.io/flannel created clusterrolebinding.rbac.authorization.k8s.io/flannel created serviceaccount/flannel created configmap/kube-flannel-cfg created daemonset.apps/kube-flannel-ds-amd64 created daemonset.apps/kube-flannel-ds-arm64 created daemonset.apps/kube-flannel-ds-arm created daemonset.apps/kube-flannel-ds-ppc64le created daemonset.apps/kube-flannel-ds-s390x created
Podの状態を確認していきます。
kubectl get pod --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE kube-system coredns-6955765f44-n92tg 1/1 Running 0 14m kube-system coredns-6955765f44-xxfj5 1/1 Running 0 14m kube-system etcd-kubemaster1.mydom.local 1/1 Running 0 14m kube-system kube-apiserver-kubemaster1.mydom.local 1/1 Running 0 14m kube-system kube-controller-manager-kubemaster1.mydom.local 1/1 Running 0 14m kube-system kube-flannel-ds-amd64-szb8d 1/1 Running 0 63s kube-system kube-proxy-dw5jc 1/1 Running 0 14m kube-system kube-scheduler-kubemaster1.mydom.local 1/1 Running 0 14m
Node状態を確認します。
# kubectl get node NAME STATUS ROLES AGE VERSION kubemaster1.mydom.local Ready master 15m v1.17.2
Worker Nodeの構築
これで最後です。
以下の手順を全Worker Nodeで実施してください。
# sysctl -n net.bridge.bridge-nf-call-iptables 0
ここで、0が出た場合以下を実施します。
# sysctl net.bridge.bridge-nf-call-iptables=1 net.bridge.bridge-nf-call-iptables = 1 # sysctl -n net.bridge.bridge-nf-call-iptables 1
Worker NodeをClusterにJoinさせます。
# kubeadm join 192.168.1.20:6443 --token owmrsk.d41wmnxetwhr2hsd --discovery-token-ca-cert-hash sha256:35e654eeeb9c125eaee57b12202aa0139729a8cd6209ef77a719c8977dc12905 [preflight] Running pre-flight checks [preflight] Reading configuration from the cluster... [preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml' [kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.15" 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 [kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap... 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.
全Worker Nodeに実施後、以下のようになります。
# kubectl get nodes NAME STATUS ROLES AGE VERSION kubemaster1.mydom.local Ready master 163m v1.15.0 kubeworker1.mydom.local Ready29s v1.15.0 kubeworker2.mydom.local Ready 127m v1.15.0
終わりに
すごく簡単にClusterが構築できますので、ぜひKubernetesを勉強する際に使ってみてください。
