Kubernetes安装集群
概述
kubeadm 是 kubernetes 的集群安装工具，能够快速安装 kubernetes 集群，安装 kubernetes 主要是安装它的各个镜像，而 kubeadm 已经为我们集成好了运行 kubernetes 所需的基本镜像。但由于国内的网络原因，在搭建环境时，无法拉取到这些镜像。此时我们只需要修改为阿里云提供的镜像服务即可解决该问题。
创建并修改配置
创建 cluster 目录，用于存放 kubeadm-config.yaml 配置文件。
shell
mkdir -p /usr/local/kubernetes/cluster && cd /usr/local/kubernetes/cluster导出 kubeadm-config.yaml 配置文件到 /usr/local/kubernetes/cluster 目录下。
shell
kubeadm config print init-defaults > kubeadm-config.yaml修改导出的 kubeadm-config.yaml 配置文件，需要修改以下有注释的地方。
shell
apiVersion: kubeadm.k8s.io/v1beta4
bootstrapTokens:
- groups:
- system:bootstrappers:kubeadm:default-node-token
token: abcdef.0123456789abcdef
ttl: 24h0m0s
usages:
- signing
- authentication
kind: InitConfiguration
localAPIEndpoint:
# 这里修改成主节点 master-01 的 IP地址
advertiseAddress: 192.168.56.100
bindPort: 6443
nodeRegistration:
# 这里修改成使用 cri-dockerd
criSocket: unix:///var/run/cri-dockerd.sock
imagePullPolicy: IfNotPresent
imagePullSerial: true
# 这里修改成主节点 master-01 的主机名
name: kubernetes-master-01
taints: null
timeouts:
controlPlaneComponentHealthCheck: 4m0s
discovery: 5m0s
etcdAPICall: 2m0s
kubeletHealthCheck: 4m0s
kubernetesAPICall: 1m0s
tlsBootstrap: 5m0s
upgradeManifests: 5m0s
---
apiServer: {}
apiVersion: kubeadm.k8s.io/v1beta4
caCertificateValidityPeriod: 87600h0m0s
certificateValidityPeriod: 8760h0m0s
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns: {}
encryptionAlgorithm: RSA-2048
etcd:
local:
dataDir: /var/lib/etcd
# 国内不能访问 Google，修改为阿里云镜像源
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
# 这里修改成对应的版本号（kubeadm是1.31.3-1.1版本的，这里就是1.31.3）
kubernetesVersion: 1.31.3
networking:
dnsDomain: cluster.local
serviceSubnet: 10.96.0.0/12
# 定义 Pod 网络的 CIDR 子网范围
podSubnet: 10.97.0.0/16
proxy: {}
scheduler: {}
---
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
cgroupDriver: systemd查看所需镜像
shell
kubeadm config images list --config kubeadm-config.yaml
# 输出如下
registry.aliyuncs.com/google_containers/kube-apiserver:v1.31.3
registry.aliyuncs.com/google_containers/kube-controller-manager:v1.31.3
registry.aliyuncs.com/google_containers/kube-scheduler:v1.31.3
registry.aliyuncs.com/google_containers/kube-proxy:v1.31.3
registry.aliyuncs.com/google_containers/coredns:v1.11.3
registry.aliyuncs.com/google_containers/pause:3.10
registry.aliyuncs.com/google_containers/etcd:3.5.15-0拉取所需镜像
shell
kubeadm config images pull --config kubeadm-config.yaml
# 输出如下
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-apiserver:v1.31.3
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-controller-manager:v1.31.3
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-scheduler:v1.31.3
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-proxy:v1.31.3
[config/images] Pulled registry.aliyuncs.com/google_containers/coredns:v1.11.3
[config/images] Pulled registry.aliyuncs.com/google_containers/pause:3.10
[config/images] Pulled registry.aliyuncs.com/google_containers/etcd:3.5.15-0安装 master 节点
执行以下命令初始化主节点，该命令指定了初始化时需要使用的配置文件，其中添加 --experimental-upload-certs 参数可以在后续执行加入节点时自动分发证书文件。追加的 tee kubeadm-init.log 用以输出日志【kubeadm init输出的日志信息会记录在kubeadm-init.log日志文件中】。
注意：如果安装 kubernetes 版本和下载的镜像版本不统一则会出现 timed out waiting for the condition 错误。中途失败或是想修改配置可以使用 kubeadm reset 命令重置配置，再做初始化操作即可。
shell
kubeadm init --config=kubeadm-config.yaml --upload-certs | tee kubeadm-init.log
# 输出如下
[init] Using Kubernetes version: v1.31.3
[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 beforehand using 'kubeadm config images pull'
W1129 15:42:31.851686 3139 checks.go:846] detected that the sandbox image "registry.k8s.io/pause:3.9" of the container runtime is inconsistent with that used by kubeadm.It is recommended to use "registry.aliyuncs.com/google_containers/pause:3.10" as the CRI sandbox image.
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [kubernetes kubernetes-master-01 kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.56.100]
[certs] Generating "apiserver-kubelet-client" certificate and key
[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/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [kubernetes-master-01 localhost] and IPs [192.168.56.100 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [kubernetes-master-01 localhost] and IPs [192.168.56.100 127.0.0.1 ::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 "super-admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[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"
[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] Starting the kubelet
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests"
[kubelet-check] Waiting for a healthy kubelet at http://127.0.0.1:10248/healthz. This can take up to 4m0s
[kubelet-check] The kubelet is healthy after 1.001205399s
[api-check] Waiting for a healthy API server. This can take up to 4m0s
[api-check] The API server is healthy after 16.001463931s
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace
[upload-certs] Using certificate key:
83e22bc58b90765c6b429e44724c95c3ef28e33f4b45a766000977cf0f70866e
[mark-control-plane] Marking the node kubernetes-master-01 as control-plane by adding the labels: [node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node kubernetes-master-01 as control-plane by adding the taints [node-role.kubernetes.io/control-plane:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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
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 192.168.56.100:6443 --token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:26b5749ce47ba91091b5ab4cbaf19d0ed333e35da6e73079fbae1e02a267b2bc配置 kubelet
在 master 节点上执行以下操作：
shell
# 创建 .kube 目录，用于存储 Kubernetes 配置文件
mkdir -p $HOME/.kube
# 复制 admin.conf 文件到 .kube 目录，作为 kubectl 的配置文件
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
# 更改配置文件的所有者为当前用户，以确保读写权限
sudo chown $(id -u):$(id -g) $HOME/.kube/config验证 master 节点是否安装成功
shell
kubectl get nodes
# 输出如下
NAME STATUS ROLES AGE VERSION
kubernetes-master-01 NotReady control-plane 4m25s v1.31.3安装工作节点
将工作节点 Worker 加入到集群中很简单，只需要在 Node 服务器上安装 kubeadm、kubectl、kubelet 三个工具，然后使用 kubeadm join 命令加入即可，这个 kubeadm join 命令就是安装 master 节点的命令输出的内容，最后几行就有安装工作节点的 kubeadm join 命令内容。
shell
# 这里需要加入--cri-socket 来指定使用 docker 还是 containerd
kubeadm join 192.168.56.100:6443 --token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:26b5749ce47ba91091b5ab4cbaf19d0ed333e35da6e73079fbae1e02a267b2bc \
--cri-socket=unix:///var/run/cri-dockerd.sock
# 输出如下
[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 -o yaml'
[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] Starting the kubelet
[kubelet-check] Waiting for a healthy kubelet at http://127.0.0.1:10248/healthz. This can take up to 4m0s
[kubelet-check] The kubelet is healthy after 1.008924661s
[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.验证工作节点是否加入集群
回到 master 节点查看是否安装成功。
shell
kubectl get nodes
# 输出如下
NAME STATUS ROLES AGE VERSION
kubernetes-master-01 NotReady control-plane 25m v1.31.3
kubernetes-worker-01 NotReady <none> 10m v1.31.3
kubernetes-worker-02 NotReady <none> 12s v1.31.3在 kubectl get nodes 的输出中，STATUS 显示为 NotReady 表示该节点尚未准备好处理 Pod，即使是 scheduler 的 状态为 Healthy 也不行。
简单的描述就是集群已经搭建成功，但是集群直接网络通信还是未配置。
查看 Namespace
shell
kubectl get namespaces
# 输出如下
NAME STATUS AGE
default Active 27m
kube-node-lease Active 27m
kube-public Active 27m
kube-system Active 27m以上这些命名空间（namespace）是 Kubernetes 集群中常见的默认命名空间，它们有各自的作用：
- default：这是 Kubernetes 中默认的命名空间，如果你没有指定命名空间，资源（如 Pod、Service、Deployment 等）会被创建在这个命名空间下。
- kube-node-lease：该命名空间用于管理节点的租约（node lease）。Kubernetes 使用租约机制来跟踪节点的健康状况，以便在节点失效时及时发现和处理。该命名空间主要由 Kubernetes 控制平面使用，用户通常不会直接与之交互。
- kube-public：这是一个用于公开的命名空间，通常用于存储集群中的公开资源。这些资源可以被集群外部的任何人访问。比如，你可能会在这个命名空间中看到一些集群级别的配置和权限控制，供集群外部使用。
- kube-system：这是 Kubernetes 集群内部使用的命名空间，用于存放 Kubernetes 系统组件的资源，如 kube-apiserver、kube-scheduler、kube-controller-manager、CoreDNS 等。这些资源是集群运行所必需的，通常不需要修改或删除。
查看 Pod 状态
- 查看所有在
kube-system命名空间中的 Pod 通常包括 Kubernetes 系统组件如 kube-apiserver、kube-controller-manager、kube-scheduler、CoreDNS 等。这些 Pod 对于集群的运行。
shell
kubectl get pods -n kube-system
# 输出如下
NAME READY STATUS RESTARTS AGE
coredns-855c4dd65d-j6pk7 0/1 Pending 0 39m
coredns-855c4dd65d-n8mds 0/1 Pending 0 39m
etcd-kubernetes-master-01 1/1 Running 0 39m
kube-apiserver-kubernetes-master-01 1/1 Running 0 39m
kube-controller-manager-kubernetes-master-01 1/1 Running 0 39m
kube-proxy-6m2cn 1/1 Running 0 39m
kube-proxy-8njlx 1/1 Running 0 24m
kube-proxy-9b787 1/1 Running 0 14m
kube-scheduler-kubernetes-master-01 1/1 Running 0 39m由输出的结果可以看出 coredns 是没有在运行的，此时我们还需要安装网络插件。