linux运维、架构之路-Kubernetes集群部署

一、kubernetes介绍

       Kubernetes简称K8s，它是一个全新的基于容器技术的分布式架构领先方案。Kubernetes(k8s)是Google开源的容器集群管理系统（谷歌内部:Borg）。在Docker技术的基础上，为容器化的应用提供部署运行、资源调度、服务发现和动态伸缩等一系列完整功能，提高了大规模容器集群管理的便捷性。

       Kubernetes是一个完备的分布式系统支撑平台，具有完备的集群管理能力，多扩多层次的安全防护和准入机制、多租户应用支撑能力、透明的服务注册和发现机制、內建智能负载均衡器、强大的故障发现和自我修复能力、服务滚动升级和在线扩容能力、可扩展的资源自动调度机制以及多粒度的资源配额管理能力。同时Kubernetes提供完善的管理工具，涵盖了包括开发、部署测试、运维监控在内的各个环节。

二、Kubernetes架构和组件

三、K8S特性

       Kubernetes是为生产环境而设计的容器调度管理系统，对于负载均衡、 服务发现、高可用、滚动升级、自动伸缩等容器云平台的功能要求有原生支持。
      一个K8s集群是由分布式存储（etcd）、服务节点（Minion， etcd现在称为Node）和控制节点（Master）构成的。所有的集群状态都保存在etcd中，Master节点上则运行集群的管理控制模块。Node节点是真正运行应用容器的主机节点，在每个Minion节点上都会运行一个Kubelet代理，控制该节点上的容器、镜像和存储卷等。

Kubernetes功能：
1. 自动化容器的部署和复制
2. 随时扩展或收缩容器规模
3. 将容器组织成组，并且提供容器间的负载均衡
4. 很容易地升级应用程序容器的新版本
5. 提供容器弹性，如果容器失效就替换它，等等…

Kubernetes解决的问题：
1. 调度 - 容器应该在哪个机器上运行
2. 生命周期和健康状况 - 容器在无错的条件下运行
3. 服务发现 - 容器在哪，怎样与它通信
4. 监控 - 容器是否运行正常
5. 认证 - 谁能访问容器
6. 容器聚合 - 如何将多个容器合并成一个工程

四、Kubernetes环境规划

1、环境

[root@k8s-master ~]# cat /etc/redhat-release
CentOS Linux release 7.2. (Core)
[root@k8s-master ~]# uname -r
3.10.-.el7.x86_64
[root@k8s-master ~]# systemctl status firewalld.service
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
[root@k8s-master ~]# getenforce
Disabled

2、服务器规划

节点及功能	主机名	IP
Master、etcd、registry	K8s-master	10.0.0.148
Node1	K8s-node-1	10.0.0.149
Node2	K8s-node-2	10.0.0.150

3、统一/etc/hosts

echo '
10.0.0.148    k8s-master
10.0.0.148    etcd
10.0.0.148    registry
10.0.0.149    k8s-node-
10.0.0.150    k8s-node-' >> /etc/hosts

4、Kubernetes集群部署架构图

五、Kubernetes集群部署

1、 Master端安装

①部署K8s依赖etcd服务

yum install etcd -y

修改配置文件：vim /etc/etcd/etcd.conf

#[Member]
#ETCD_CORS=""
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
#ETCD_WAL_DIR=""
#ETCD_LISTEN_PEER_URLS="http://localhost:2380"
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"
#ETCD_MAX_SNAPSHOTS=""
#ETCD_MAX_WALS=""
ETCD_NAME=master
#ETCD_SNAPSHOT_COUNT=""
#ETCD_HEARTBEAT_INTERVAL=""
#ETCD_ELECTION_TIMEOUT=""
#ETCD_QUOTA_BACKEND_BYTES=""
#ETCD_MAX_REQUEST_BYTES=""
#ETCD_GRPC_KEEPALIVE_MIN_TIME="5s"
#ETCD_GRPC_KEEPALIVE_INTERVAL="2h0m0s"
#ETCD_GRPC_KEEPALIVE_TIMEOUT="20s"
#
#[Clustering]
#ETCD_INITIAL_ADVERTISE_PEER_URLS="http://localhost:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://etcd:2379,http://etcd:4001"
#ETCD_ADVERTISE_CLIENT_URLS="http://localhost:2379"
#ETCD_DISCOVERY=""
#ETCD_DISCOVERY_FALLBACK="proxy"
#ETCD_DISCOVERY_PROXY=""
#ETCD_DISCOVERY_SRV=""
#ETCD_INITIAL_CLUSTER="default=http://localhost:2380"
#ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
#ETCD_INITIAL_CLUSTER_STATE="new"
#ETCD_STRICT_RECONFIG_CHECK="true"
#ETCD_ENABLE_V2="true"
#
#[Proxy]
#ETCD_PROXY="off"
#ETCD_PROXY_FAILURE_WAIT=""
#ETCD_PROXY_REFRESH_INTERVAL=""
#ETCD_PROXY_DIAL_TIMEOUT=""
#ETCD_PROXY_WRITE_TIMEOUT=""
#ETCD_PROXY_READ_TIMEOUT=""
#
#[Security]
#ETCD_CERT_FILE=""
#ETCD_KEY_FILE=""
#ETCD_CLIENT_CERT_AUTH="false"
#ETCD_TRUSTED_CA_FILE=""
#ETCD_AUTO_TLS="false"
#ETCD_PEER_CERT_FILE=""
#ETCD_PEER_KEY_FILE=""
#ETCD_PEER_CLIENT_CERT_AUTH="false"
#ETCD_PEER_TRUSTED_CA_FILE=""
#ETCD_PEER_AUTO_TLS="false"
#
#[Logging]
#ETCD_DEBUG="false"
#ETCD_LOG_PACKAGE_LEVELS=""
#ETCD_LOG_OUTPUT="default"
#
#[Unsafe]
#ETCD_FORCE_NEW_CLUSTER="false"
#
#[Version]
#ETCD_VERSION="false"
#ETCD_AUTO_COMPACTION_RETENTION=""
#
#[Profiling]
#ETCD_ENABLE_PPROF="false"
#ETCD_METRICS="basic"
#
#[Auth]
#ETCD_AUTH_TOKEN="simple"

启动并验证etcd集群状态

[root@k8s-master ~]# systemctl start etcd.service
[root@k8s-master ~]# systemctl enable etcd.service
Created symlink from /etc/systemd/system/multi-user.target.wants/etcd.service to /usr/lib/systemd/system/etcd.service.
[root@k8s-master ~]# etcdctl -C http://etcd:4001 cluster-health
member 8e9e05c52164694d is healthy: got healthy result from http://etcd:2379
cluster is healthy
[root@k8s-master ~]# etcdctl -C http://etcd:2379 cluster-health
member 8e9e05c52164694d is healthy: got healthy result from http://etcd:2379
cluster is healthy

②安装Docker

添加yum源

wget -O /etc/yum.repos.d/docker-ce.repo https://mirrors.ustc.edu.cn/docker-ce/linux/centos/docker-ce.repo
sed -i 's#download.docker.com#mirrors.ustc.edu.cn/docker-ce#g' /etc/yum.repos.d/docker-ce.repo

 安装docker

yum install docker-ce -y

配置Docker配置文件，使其允许从registry中拉取镜像

[root@k8s-master ~]# vim /etc/sysconfig/docker
# /etc/sysconfig/docker
# Modify these options if you want to change the way the docker daemon runs
OPTIONS='--selinux-enabled --log-driver=journald --signature-verification=false'
if [ -z "${DOCKER_CERT_PATH}" ]; then
    DOCKER_CERT_PATH=/etc/docker
fi
OPTIONS='--insecure-registry registry:5000'

启动docker并设置成开机启动

[root@k8s-master ~]# systemctl start docker.service
[root@k8s-master ~]# systemctl enable docker.service
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

③安装kubernets

yum install kubernetes -y
#安装k8s的时候会自动安装docker，如果先安装docker版本冲突#
yum list installed | grep docker
yum remove -y docker-ce.x86_64
yum install kubernetes -y

④配置配置并启动kubernetes

修改/etc/kubernetes/apiserver配置文件

###
# 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=0.0.0.0"

# 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://etcd:2379"

# Address range to use for services
KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"

# default admission control policies
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota"
# Add your own!
KUBE_API_ARGS=""

修改/etc/kubernetes/config配置文件

###
# 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,  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://k8s-master:8080"

启动K8S相关服务并设置开机启动

[root@k8s-master ~]# systemctl start kube-controller-manager.service
[root@k8s-master ~]# systemctl enable kube-controller-manager.service
Created symlink from /etc/systemd/system/multi-user.target.wants/kube-controller-manager.service to /usr/lib/systemd/system/kube-controller-manager.service.
[root@k8s-master ~]# systemctl start kube-scheduler.service
[root@k8s-master ~]# systemctl enable kube-scheduler.service
Created symlink from /etc/systemd/system/multi-user.target.wants/kube-scheduler.service to /usr/lib/systemd/system/kube-scheduler.service.

2、Node节点部署
①安装kubernets、docker

yum install kubernetes -y

启动docker并设置开机启动

[root@k8s-node- ~]# systemctl start docker.service
[root@k8s-node- ~]# systemctl enable docker.service
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

②配置并启动kubernetes

修改/etc/kubernetes/config配置文件

###
# 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,  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://k8s-master:8080"

修改/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=0.0.0.0"

# 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=k8s-node-1"
# location of the api-server
KUBELET_API_SERVER="--api-servers=http://k8s-master: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=""

 启动node节点服务并配置开机启动

systemctl start kubelet.service
systemctl enable kubelet.service
systemctl start kube-proxy.service
systemctl enable kube-proxy.service

3、在master上查看集群中节点及节点状态

[root@k8s-master ~]# kubectl -s http://k8s-master:8080 get node
NAME         STATUS    AGE
k8s-node-   Ready     1m
k8s-node-   Ready     1m
[root@k8s-master ~]# kubectl get nodes
NAME         STATUS    AGE
k8s-node-   Ready     3m
k8s-node-   Ready     3m

4、创建覆盖网络——Flannel

①在master、node上均执行如下命令，进行安装

yum install flannel -y

master、node上配置Flannel，

vi /etc/sysconfig/flanneld

# Flanneld configuration options  

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

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

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

②设置etcd网络

etcdctl mk /atomic.io/network/config '{ "Network": "172.16.0.0/16" }'

启动Flannel,并重启docker、kubernets服务

Master:
systemctl start flanneld.service
systemctl enable flanneld.service
service docker restart
systemctl restart kube-apiserver.service
systemctl restart kube-controller-manager.service
systemctl restart kube-scheduler.service

Node:
systemctl start flanneld.service
systemctl enable flanneld.service
service docker restart
systemctl restart kubelet.service
systemctl restart kube-proxy.service