K8S集群搭建

摘要

是借鉴网上的几篇文章加上自己的理解整理得到的结果，去掉了一些文章中比较冗余的组件和操作，力争做到部署简单化。
### K8S组件说明
Kubernetes包含两种节点角色：master节点和minion节点

  • Master 节点负责对外提供一系列管理集群的 API 接口，并且通过和 Minion 节点交互来实现对集群的操作管理。
  • Minion 节点是实际运行 Docker 容器的节点，负责和节点上运行的 Docker 进行交互，并且提供了代理功能。

master节点组件

apiserver：用户和 kubernetes 集群交互的入口，封装了核心对象的增删改查操作，提供了 RESTFul 风格的 API 接口，通过 etcd 来实现持久化并维护对象的一致性。

scheduler：负责集群资源的调度和管理，例如当有 pod 异常退出需要重新分配机器时，scheduler 通过一定的调度算法从而找到最合适的节点。

controller-manager：主要是用于保证 replicationController 定义的复制数量和实际运行的 pod 数量一致，另外还保证了从 service 到 pod 的映射关系总是最新的。

etcd：key-value键值存储数据库，用来存储kubernetes的信息的。

minion节点组件

kubelet：运行在 minion 节点，负责和节点上的 Docker 交互，例如启停容器，监控运行状态等。

proxy：运行在 minion 节点，负责为 pod 提供代理功能，会定期从 etcd 获取 service 信息，并根据 service 信息通过修改 iptables 来实现流量转发（最初的版本是直接通过程序提供转发功能，效率较低。），将流量转发到要访问的 pod 所在的节点上去。

flannel：Flannel 是 CoreOS 团队针对 Kubernetes 设计的一个覆盖网络（Overlay Network）工具，需要另外下载部署。我们知道当我们启动 Docker 后会有一个用于和容器进行交互的 IP 地址，如果不去管理的话可能这个 IP 地址在各个机器上是一样的，并且仅限于在本机上进行通信，无法访问到其他机器上的 Docker 容器。Flannel 的目的就是为集群中的所有节点重新规划 IP 地址的使用规则，从而使得不同节点上的容器能够获得同属一个内网且不重复的 IP 地址，并让属于不同节点上的容器能够直接通过内网 IP 通信。

架构图

K8S架构图

前期准备

os：centos 7.5.1804

IP hostname 服务
44.201 node1 kube-apiservice,kube-scheduler,kube-controller-manager,etcd
44.202 node2 kubelet,kube-proxy,flanneld,docker
44.203 node3 kubelet,kube-proxy,flanneld,docker

安装

master节点

yum install kubernetes-master etcd -y

minion节点

yum install kubernetes-node flannel -y

配置

master节点

修改/etc/etcd/etcd.conf
[root@node1 ~]# vim /etc/etcd/etcd.conf 

#[Member]
#ETCD_CORS=""
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
#ETCD_WAL_DIR=""
ETCD_LISTEN_PEER_URLS="http://192.168.44.201:2380"
ETCD_LISTEN_CLIENT_URLS="http://192.168.44.201:2379,http://127.0.0.1:2379"
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
ETCD_NAME="default"
#ETCD_SNAPSHOT_COUNT="100000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
#ETCD_QUOTA_BACKEND_BYTES="0"
#ETCD_MAX_REQUEST_BYTES="1572864"
#ETCD_GRPC_KEEPALIVE_MIN_TIME="5s"
#ETCD_GRPC_KEEPALIVE_INTERVAL="2h0m0s"
#ETCD_GRPC_KEEPALIVE_TIMEOUT="20s"
#
#[Clustering]
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.44.201:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://192.168.44.201:2379"
#ETCD_DISCOVERY=""
#ETCD_DISCOVERY_FALLBACK="proxy"
#ETCD_DISCOVERY_PROXY=""
#ETCD_DISCOVERY_SRV=""
ETCD_INITIAL_CLUSTER="default=http://192.168.44.201:2380"
....
针对几个URLS做下简单的解释：
[member]
ETCD_NAME ：ETCD的节点名
ETCD_DATA_DIR：ETCD的数据存储目录
ETCD_SNAPSHOT_COUNTER：多少次的事务提交将触发一次快照
ETCD_HEARTBEAT_INTERVAL：ETCD节点之间心跳传输的间隔，单位毫秒
ETCD_ELECTION_TIMEOUT：该节点参与选举的最大超时时间，单位毫秒
ETCD_LISTEN_PEER_URLS：该节点与其他节点通信时所监听的地址列表，多个地址使用逗号隔开，其格式可以划分为scheme://IP:PORT，这里的scheme可以是http、https
ETCD_LISTEN_CLIENT_URLS：该节点与客户端通信时监听的地址列表
[cluster]
ETCD_INITIAL_ADVERTISE_PEER_URLS：该成员节点在整个集群中的通信地址列表，这个地址用来传输集群数据的地址。因此这个地址必须是可以连接集群中所有的成员的。
ETCD_INITIAL_CLUSTER：配置集群内部所有成员地址，其格式为：ETCD_NAME=ETCD_INITIAL_ADVERTISE_PEER_URLS，如果有多个使用逗号隔开
ETCD_ADVERTISE_CLIENT_URLS：广播给集群中其他成员自己的客户端地址列表

注：k8s中只需要master节点配置etcd,因为其他节点共享同一个etcd服务

修改/etc/kubernetes/apiserver
[root@node1 ~]# vim /etc/kubernetes/apiserver 

###
# kubernetes system config
#
# The following values are used to configure the kube-apiserver
#

# The address on the local server to listen to.
#KUBE_API_ADDRESS="--insecure-bind-address=127.0.0.1"
KUBE_API_ADDRESS="--address=0.0.0.0"  ##API-server绑定的安全IP只有127.0.0.1，相当于一个白名单，修改成"--address=0.0.0.0""，表示运行所有节点进行访问。

# The port on the local server to listen on.
KUBE_API_PORT="--port=8080"

# Port minions listen on
KUBELET_PORT="--kubelet-port=10250"

# Comma separated list of nodes in the etcd cluster
KUBE_ETCD_SERVERS="--etcd-servers=http://192.168.44.201:2379"  #etcd服务

# Address range to use for services
KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.1.0.0/16"

# default admission control policies
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota"

# Add your own!
KUBE_API_ARGS="--service_account_key_file=/etc/kubernetes/serviceaccount.key"
修改/etc/kubernetes/controller-manager
[root@node1 ~]# vim /etc/kubernetes/controller-manager

###
# The following values are used to configure the kubernetes controller-manager

# defaults from config and apiserver should be adequate

# Add your own!
KUBE_CONTROLLER_MANAGER_ARGS="--service_account_private_key_file=/etc/kubernetes/serviceaccount.key"

以下文件在操作过程中，未修改过，不过也比较重要

/usr/lib/systemd/system/etcd.service
[root@node1 kubernetes]# cat /usr/lib/systemd/system/etcd.service 
[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target

[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
EnvironmentFile=-/etc/etcd/etcd.conf
User=etcd
# set GOMAXPROCS to number of processors
ExecStart=/bin/bash -c "GOMAXPROCS=$(nproc) /usr/bin/etcd --name=\"${ETCD_NAME}\" --data-dir=\"${ETCD_DATA_DIR}\" --listen-client-urls=\"${ETCD_LISTEN_CLIENT_URLS}\""
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
[root@node1 kubernetes]#

minion节点

修改/etc/kubernetes/config
[root@node2 kubernetes]# vim /etc/kubernetes/config 

###
# kubernetes system config
#
# The following values are used to configure various aspects of all
# kubernetes services, including
#
#   kube-apiserver.service
#   kube-controller-manager.service
#   kube-scheduler.service
#   kubelet.service
#   kube-proxy.service
# logging to stderr means we get it in the systemd journal
KUBE_LOGTOSTDERR="--logtostderr=true"

# journal message level, 0 is debug
KUBE_LOG_LEVEL="--v=0"

# Should this cluster be allowed to run privileged docker containers
KUBE_ALLOW_PRIV="--allow-privileged=false"

# How the controller-manager, scheduler, and proxy find the apiserver
KUBE_MASTER="--master=http://192.168.44.201:8080"
修改/etc/kubernetes/kubelet
[root@node2 kubernetes]# vim /etc/kubernetes/kubelet 

###
# kubernetes kubelet (minion) config

# The address for the info server to serve on (set to 0.0.0.0 or "" for all interfaces)
KUBELET_ADDRESS="--address=192.168.44.202"  ##修改ip

# The port for the info server to serve on
KUBELET_PORT="--port=10250"

# You may leave this blank to use the actual hostname
KUBELET_HOSTNAME="--hostname-override=192.168.44.202" ## 修改ip

# location of the api-server
KUBELET_API_SERVER="--api-servers=http://192.168.44.201:8080"

# pod infrastructure container
KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=registry.access.redhat.com/rhel7/pod-infrastructure:latest"

# Add your own!
KUBELET_ARGS=""

注：修改对应的ip地址

修改/etc/sysconfig/flanneld

[root@node2 kubernetes]# vim /etc/sysconfig/flanneld 

# Flanneld configuration options  

# etcd url location.  Point this to the server where etcd runs
FLANNEL_ETCD_ENDPOINTS="http://192.168.44.201:2379"

# etcd config key.  This is the configuration key that flannel queries
# For address range assignment
FLANNEL_ETCD_PREFIX="/coreos.com/network"

# Any additional options that you want to pass
#FLANNEL_OPTIONS=""

注：node3与node2上面配置相同
以下文件在操作过程中，未修改过，不过也比较重要

/usr/lib/systemd/system/flanneld.service
[root@node2 kubernetes]# cat /usr/lib/systemd/system/flanneld.service 
[Unit]
Description=Flanneld overlay address etcd agent
After=network.target
After=network-online.target
Wants=network-online.target
After=etcd.service
Before=docker.service

[Service]
Type=notify
EnvironmentFile=/etc/sysconfig/flanneld
EnvironmentFile=-/etc/sysconfig/docker-network
ExecStart=/usr/bin/flanneld-start $FLANNEL_OPTIONS
#ExecStart=/usr/bin/flanneld --iface ens33 $FLANNEL_OPTIONS
ExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
Restart=on-failure

[Install]
WantedBy=multi-user.target
WantedBy=docker.service
/usr/lib/systemd/system/docker.service
[root@node2 kubernetes]# cat /usr/lib/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.com
After=network.target flanneld.service
Wants=docker-storage-setup.service
Requires=flanneld.service  #这个参数应该可以没有，只要docker的启动顺序在flanneld之后就OK

[Service]
Type=notify
NotifyAccess=main
EnvironmentFile=-/run/containers/registries.conf
EnvironmentFile=-/etc/sysconfig/docker
EnvironmentFile=-/etc/sysconfig/docker-storage
EnvironmentFile=-/etc/sysconfig/docker-network
Environment=GOTRACEBACK=crash
Environment=DOCKER_HTTP_HOST_COMPAT=1
Environment=PATH=/usr/libexec/docker:/usr/bin:/usr/sbin
ExecStart=/usr/bin/dockerd-current \
          --add-runtime docker-runc=/usr/libexec/docker/docker-runc-current \
          --default-runtime=docker-runc \
          --exec-opt native.cgroupdriver=systemd \
          --userland-proxy-path=/usr/libexec/docker/docker-proxy-current \
          --init-path=/usr/libexec/docker/docker-init-current \
          --seccomp-profile=/etc/docker/seccomp.json \
          $OPTIONS \
          $DOCKER_STORAGE_OPTIONS \
          $DOCKER_NETWORK_OPTIONS \
          $ADD_REGISTRY \
          $BLOCK_REGISTRY \
          $INSECURE_REGISTRY \
      $REGISTRIES
ExecReload=/bin/kill -s HUP $MAINPID
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
TimeoutStartSec=0
Restart=on-abnormal
KillMode=process

[Install]
WantedBy=multi-user.target

启动

minion节点上的flanneld服务必须要在master上的etcd服务启动之后再启动

master节点

systemctl start etcd
systemctl enable etcd
systemctl start kube-apiserver
systemctl enable kube-apiserver
systemctl start kube-scheduler
sysemtctl enable kube-scheduler
systemctl start kube-controller-manager
systemctl enable kube-controller-manager

minion节点

systemctl start kubelet
systemctl enable kubelet
systemctl start kube-proxy
systemctl enable kube-proxy
systemctl start flanneld
systemctl enable flanneld
systemctl start docker 
systemctl enable docker

注：如果之前docker启动，并且docker0存在（ip addr），则需要先将docker停止（systemctl stop docker），并且删掉docker0(ip link delete docker0)

注意事项

1.每个节点的防火墙和selinux必须关掉
  • 关闭防火墙
systemctl stop firewalld
systemctl disable firewalld
  • 关闭selinux
临时关闭：
setenforce 0

永久关闭：
[root@node2 kubernetes]# vim /etc/selinux/config 


# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
#     targeted - Targeted processes are protected,
#     minimum - Modification of targeted policy. Only selected processes are protected. 
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted
2.仅仅关闭防火墙，pod之间也是无法ping通。需要关闭iptables规则（这个很坑，找了很多资料才发现的问题）
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -F
iptables -L -n

web界面管理kuberneters

1.下载kubernetes-dashboard-amd64

docker search  kubernetes-dashboard-amd64

docker images

2.将kubernetes-dashboard-amd64发送到本地私有仓库

docker tag siriuszg/kubernetes-dashboard-amd64:latest 192.168.44.201:5000/kubernetes-dashboard-amd64:latest

配置私有仓库方法

3.在master服务器上创建kubernetes-dashboard.yaml文件

[root@node1 ~]# vim  kubernetes-dashboard.yaml 

      # Comment the following annotation if Dashboard must not be deployed on master
      annotations:
        scheduler.alpha.kubernetes.io/tolerations: |
          [
            {
              "key": "dedicated",
              "operator": "Equal",
              "value": "master",
              "effect": "NoSchedule"
            }
          ]
    spec:
      containers:
      - name: kubernetes-dashboard
        image: 192.168.44.201:5000/kubernetes-dashboard-amd64
        imagePullPolicy: Always
        ports:
        - containerPort: 9090
          protocol: TCP
        args:
          # Uncomment the following line to manually specify Kubernetes API server Host  
          # If not specified, Dashboard will attempt to auto discover the API server and connect  
          # to it. Uncomment only if the default does not work.  
          - --apiserver-host=192.168.44.201:8080
        livenessProbe:
          httpGet:
            path: /
            port: 9090
          initialDelaySeconds: 30
          timeoutSeconds: 30
---
kind: Service
apiVersion: v1
metadata:
  labels:
    app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 9090
  selector:
    app: kubernetes-dashboard

4.创建kubernetes-dashboard

[root@node1 ~]# kubectl create -f kubernetes-dashboard.yaml
Error from server (AlreadyExists): error when creating "kubernetes-dashboard.yaml": deployments.extensions "kubernetes-dashboard" already exists
Error from server (AlreadyExists): error when creating "kubernetes-dashboard.yaml": services "kubernetes-dashboard" already exists

出现上面错误，需要将kubernetes-dashboard的有关配置全部删除

[root@node1 ~]# kubectl delete -f kubernetes-dashboard.yaml

5. 查看pod详情


通过192.168.44.201:8080/ui可以访问

6.查看service详情


通过192.168.44.203:8080/ui可以访问

6.web界面

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本文链接：https://www.cnblogs.com/zhangjxblog/p/12167535.html