쿠버네티스 클러스터 환경 구성(Ubuntu 18.04)

우분투 18.04 서버에 쿠버네티스 클러스터 환경(master, worker-node1, worker-node2) 구성하는 방법에 대해 알아보자.

쿠버네티스 클러스터 구성

 

우분투 18.04 서버가 3대 준비되어 있는 상태에서 시작한다.

 

1. Docker 설치(모든 서버에 설치)

repository를 이용한 설치(참고 URL)

1) Set up the repository

# Update the apt package index and install packages to allow apt to use a repository over HTTPS:
sudo apt-get update
sudo apt-get install \
    ca-certificates \
    curl \
    gnupg \
    lsb-release

# Add Docker’s official GPG key:
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Use the following command to set up the repository:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

2) Install Docker Engine

# Update the apt package index:
sudo apt-get update

    # GPG 에러가 발생하는 경우
    sudo chmod a+r /etc/apt/keyrings/docker.gpg
    sudo apt-get update

# Install Docker Engine, containerd, and Docker Compose.
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin

# Verify that the Docker Engine installation is successful by running the hello-world image:
sudo docker run hello-world

 

2. Kubernetes 설치(모든 서버에 설치)

repository를 이용한 설치(참고 URL)

1) 설치 전 환경설정

# Swap disabled
swapoff -a && sed -i '/swap/s/^/#/' /etc/fstab

# Letting iptables see bridged traffic
cat <<EOF > /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

# Disable firewall
systemctl stop firewalld 
systemctl disable firewalld

2) kubeadm, kubelet 및 kubectl 설치

# apt 패키지 색인을 업데이트하고, 쿠버네티스 apt 리포지터리를 사용하는 데 필요한 패키지를 설치
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl

# 구글 클라우드의 공개 사이닝 키를 다운로드
sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg

# 쿠버네티스 apt 리포지터리를 추가
echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

# apt 패키지 색인을 업데이트하고, kubelet, kubeadm, kubectl을 설치하고 해당 버전을 고정
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

 

3. control-plane 구성 (master 노드에서만 설정)

1) kubeadm init

kubeadm init

 ~~~~~~~~~~~
 
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:

kubeadm join 192.168.137.10:6443 --token hj6hei.zlz3v0531x9jjyqs \
	--discovery-token-ca-cert-hash sha256:4d1b431f15995807ac22cb1f7dc4f6d1d2004e271a3c24a8bdb928e8536cb703 


# 일반계정에서도 k8s 를 사용하려면 일반계정으로 접속 후 아래 명령어 입력
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# root 에서 k8s 를 사용하려면 아래 명령어 입력
export KUBECONFIG=/etc/kubernetes/admin.conf

# kubeadm join 관련 메시지는 따로 저장

- kubeadm init 에러 발생 시

# 아래 오류가 발생하는 경우
[init] Using Kubernetes version: v1.26.0
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR CRI]: container runtime is not running: output: E0108 06:35:18.830142   12240 remote_runtime.go:948] "Status from runtime service failed" err="rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
time="2023-01-08T06:35:18Z" level=fatal msg="getting status of runtime: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService"
, error: exit status 1
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

# 아래 명령어 실행 후 다시 kubeadm init 실행
rm /etc/containerd/config.toml 
systemctl restart containerd

2) Pod network add-on

# Weave Net 설치
kubectl apply -f "https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml"

- 설치 후 상태 확인

kubectl get nodes
NAME         STATUS   ROLES           AGE   VERSION
k8s-master   Ready    control-plane   24m   v1.26.0

- kubectl 뒤에 명령어 자동 완성을 위한 설정

source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc

 

4. worker node 구성(worker 노드에서만 설정)

1) worker node join

# kubeadm init 출력 메시지로 나온 join 관련 명령어 입력
kubeadm join 192.168.137.10:6443 --token hj6hei.zlz3v0531x9jjyqs --discovery-token-ca-cert-hash sha256:4d1b431f15995807ac22cb1f7dc4f6d1d2004e271a3c24a8bdb928e8536cb703

# join 결과 확인
kubectl get nodes -o wide
NAME         STATUS   ROLES           AGE    VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION       CONTAINER-RUNTIME
k8s-master   Ready    control-plane   31m    v1.26.0   192.168.137.10   <none>        Ubuntu 18.04.6 LTS   4.15.0-156-generic   containerd://1.6.14
k8s-node1    Ready    <none>          108s   v1.26.0   192.168.137.11   <none>        Ubuntu 18.04.6 LTS   4.15.0-156-generic   containerd://1.6.14
k8s-node2    Ready    <none>          81s    v1.26.0   192.168.137.12   <none>        Ubuntu 18.04.6 LTS   4.15.0-156-generic   containerd://1.6.14

 

이제 원하는 pod를 실행하면 된다.

 

끝~!