OpenShift简介

微服务架构应用日渐广泛，Docker和Kubernetes技术是不可或缺的。Red Hat OpenShift 3是建立在Docker和Kubernetes基础之上的容器应用平台，用于开发和部署企业应用程序。

OpenShift版本

OpenShift Dedicated(Enterprise)

• Private, high-availability OpenShift clusters hosted on Amazon Web Services or Google Cloud Platform
• Delivered as a hosted service and supported by Red Hat

OpenShift Container Platform(Enterprise)

• Across cloud and on-premise infrastructure
• Customizable, with full administrative control

OKD
OpenShift开源社区版(Origin Community Distribution of Kubernetes)

OpenShift架构

• Master Node提供的组件：API Server (负责处理客户端请求, 包括node、user、 administrator和其他的infrastructure系统)；Controller Manager Server (包括scheduler和replication controller)；OpenShift客户端工具 (oc)
• Compute Node(Application Node) 部署application
• Infra Node 运行router、image registry和其他的infrastructure服务
• etcd 可以部署在Master Node，也可以单独部署， 用来存储共享数据：master state、image、 build、deployment metadata等
• Pod 最小的Kubernetes object，可以部署一个或多个container

安装计划

软件环境

• AWS RHEL 7.5
• OKD 3.10
• Ansible 2.6.3
• Docker 1.13.1
• Kubernetes 1.10

使用Ansible安装openshift，仅需配置一些Node信息和参数即可完成集群安装，大大提高了安装速度。

硬件需求

Masters

• 最小4 vCPU
• 最小16 GB RAM
• /var/最小40 GB硬盘空间
• /usr/local/bin/最小1 GB硬盘空间
• 临时目录最小1 GB硬盘空间

Nodes

• 1 vCPU
• 最小8 GB RAM
• /var/最小15 GB硬盘空间
• /usr/local/bin/最小1 GB硬盘空间
• 临时目录最小1 GB硬盘空间

安装类型

RPM安装通过包管理器来安装和配置服务，system container安装使用系统容器镜像来安装服务， 服务运行在独立的容器内。
从OKD 3.10开始， 如果使用Red Hat Enterprise Linux (RHEL)操作系统，将使用RPM方法安装OKD组件。如果使用RHEL Atomic，将使用system container方法。不同安装类型提供相同的功能， 安装类型的选择依赖于操作系统、你想使用的服务管理和系统升级方法。

本文使用RPM安装方法。

Node ConfigMaps

Configmaps定义Node配置， OKD 3.10忽略openshift_node_labels值。默认创建了下面的ConfigMaps：

• node-config-master
• node-config-infra
• node-config-compute
• node-config-all-in-one
• node-config-master-infra

集群安装时选择node-config-master、node-config-infra、node-config-compute。

环境场景

• Master、Compute、Infra Node各一，etcd部署在master上
• Master、Compute、Infra Node各三，etcd部署在master上

为快速了解OpenShift安装，我们先使用第一种环境，成功后再安装第二种环境。Ansible一般使用单独的机器，两种情况分别需要创建4和10台EC2。

前期准备

更新系统

# yum update

Red Hat订阅

安装OpenShift需要Red Hat账号并订阅了RHEL，依次执行以下命令启用必须的repo:

# subscription-manager register
# subscription-manager list --available
# subscription-manager attach --pool=8a85f98b62dd96fc0162f04efb0e6350
# subscription-manager repos --list
# subscription-manager repos --enable rhel-7-server-ansible-2.6-debug-rpms
# subscription-manager repos --enable rhel-7-server-rpms
# subscription-manager repos --enable rhel-7-server-extras-rpms

检查SELinux

检查/etc/selinux/config，确保内容如下：

SELINUX=enforcing
SELINUXTYPE=targeted

配置DNS

为了使用更清晰的名字，需要创建额外的DNS服务器，为EC2配置合适的域名，如下：

master1.itrunner.org    A   10.64.33.100
master2.itrunner.org    A   10.64.33.103
node1.itrunner.org      A   10.64.33.101
node2.itrunner.org      A   10.64.33.102

EC2需要配置DNS服务器，创建dhclient.conf文件

# vi /etc/selinux/config

添加如下内容：

supersede domain-name-servers 10.164.18.18;

配置完毕后需要重启才能生效，重启后/etc/resolv.conf内容如下：

# Generated by NetworkManager
search cn-north-1.compute.internal
nameserver 10.164.18.18

OKD使用了dnsmasq，安装成功后会自动配置所有Node，/etc/resolv.conf会被修改，nameserver变为本机IP。Pod将使用Node作为DNS，Node转发请求。

# nameserver updated by /etc/NetworkManager/dispatcher.d/99-origin-dns.sh
# Generated by NetworkManager
search cluster.local cn-north-1.compute.internal itrunner.org
nameserver 10.64.33.100

配置hostname

hostnamectl set-hostname --static master1.itrunner.org

编辑/etc/cloud/cloud.cfg文件，在底部添加以下内容：

preserve_hostname: true

安装基础包

所有Node需安装。

# yum install wget git net-tools bind-utils yum-utils iptables-services bridge-utils bash-completion kexec-tools sos psacct

安装Docker

所有Node需安装。

# yum install docker
# systemctl enable docker
# systemctl start docker

检查docker安装：

# docker info

安装Ansible

仅Ansible EC2需安装。

# yum install ansible

Ansible需要能访问其他所有机器才能完成安装，因此需要配置免密登录。将密钥拷贝到ec2-user/.ssh目录下，然后授权：

$ cd .ssh/
$ chmod 600 *

配置成功后逐一测试连接：

ssh master1.itrunner.org

如使用密码或需要密码的密钥登录，请使用keychain。

配置Security Group

配置ELB

第二种场景下需要配置ELB。
使用外部ELB时，Inventory文件不需定义lb，需要指定openshift_master_cluster_hostname、openshift_master_cluster_public_hostname、openshift_master_default_subdomain三个参数（请参见后面章节）。
openshift_master_cluster_hostname和openshift_master_cluster_public_hostname负责master的load balance，ELB定义时指向Master Node，其中openshift_master_cluster_hostname供内部使用，openshift_master_cluster_public_hostname供外部访问（Web Console），两者可以设置为同一域名，但openshift_master_cluster_hostname所使用的ELB必须配置为Passthrough。


为了安全，生产环境openshift_master_cluster_hostname和openshift_master_cluster_public_hostname应设置为两个不同域名。
openshift_master_default_subdomain定义OpenShift部署应用的域名，ELB指向Infra Node。
因此，共需创建三个ELB：

• openshift_master_cluster_hostname 必须创建网络负载均衡器，协议为TCP，默认端口8443，Target要使用IP方式。
• openshift_master_cluster_public_hostname ELB/ALB，协议HTTPS，默认端口8443。
• openshift_master_default_subdomain ELB/ALB，协议HTTPS，默认端口443；协议HTTP，默认端口80。

为了方便使用，openshift_master_cluster_public_hostname、openshift_master_default_subdomain一般配置为企业的域名，不直接使用AWS ELB的DNS名称。

安装OpenShift

下载openshift-ansible

$ cd ~
$ git clone https://github.com/openshift/openshift-ansible
$ cd openshift-ansible
$ git checkout release-3.10

配置Inventory文件

Inventory文件定义了host和配置信息，默认文件为/etc/ansible/hosts。
场景一
master、compute、infra各一个结点，etcd部署在master上。

# Create an OSEv3 group that contains the masters, nodes, and etcd groups
[OSEv3:children]
masters
nodes
etcd

# Set variables common for all OSEv3 hosts
[OSEv3:vars]
# SSH user, this user should allow ssh based auth without requiring a password
ansible_ssh_user=ec2-user

# If ansible_ssh_user is not root, ansible_become must be set to true
ansible_become=true

openshift_deployment_type=origin
openshift_disable_check=disk_availability,docker_storage,memory_availability,docker_image_availability

# uncomment the following to enable htpasswd authentication; defaults to DenyAllPasswordIdentityProvider
openshift_master_identity_providers=[{‘name‘: ‘htpasswd_auth‘, ‘login‘: ‘true‘, ‘challenge‘: ‘true‘, ‘kind‘: ‘HTPasswdPasswordIdentityProvider‘}]
# Defining htpasswd users
#openshift_master_htpasswd_users={‘user1‘: ‘<pre-hashed password>‘, ‘user2‘: ‘<pre-hashed password>‘
# or
#openshift_master_htpasswd_file=<path to local pre-generated htpasswd file>

# host group for masters
[masters]
master1.itrunner.org

# host group for etcd
[etcd]
master1.itrunner.org

# host group for nodes, includes region info
[nodes]
master1.itrunner.org openshift_node_group_name=‘node-config-master‘
compute1.itrunner.org openshift_node_group_name=‘node-config-compute‘
infra1.itrunner.org openshift_node_group_name=‘node-config-infra‘

场景二
master、compute、infra各三个结点，在非生产环境下，load balance可以不使用外部ELB，使用HAProxy，etcd可以单独部署，也可以与master部署在一起。

1. Multiple Masters Using Native HA with External Clustered etcd

# Create an OSEv3 group that contains the master, nodes, etcd, and lb groups.
# The lb group lets Ansible configure HAProxy as the load balancing solution.
# Comment lb out if your load balancer is pre-configured.
[OSEv3:children]
masters
nodes
etcd
lb

# Set variables common for all OSEv3 hosts
[OSEv3:vars]
ansible_ssh_user=root
openshift_deployment_type=origin

# uncomment the following to enable htpasswd authentication; defaults to AllowAllPasswordIdentityProvider
#openshift_master_identity_providers=[{‘name‘: ‘htpasswd_auth‘, ‘login‘: ‘true‘, ‘challenge‘: ‘true‘, ‘kind‘: ‘HTPasswdPasswordIdentityProvider‘}]

# Native high availbility cluster method with optional load balancer.
# If no lb group is defined installer assumes that a load balancer has
# been preconfigured. For installation the value of
# openshift_master_cluster_hostname must resolve to the load balancer
# or to one or all of the masters defined in the inventory if no load
# balancer is present.
openshift_master_cluster_method=native
openshift_master_cluster_hostname=openshift-internal.example.com
openshift_master_cluster_public_hostname=openshift-cluster.example.com

# apply updated node defaults
openshift_node_kubelet_args={‘pods-per-core‘: [‘10‘], ‘max-pods‘: [‘250‘], ‘image-gc-high-threshold‘: [‘90‘], ‘image-gc-low-threshold‘: [‘80‘]}

# enable ntp on masters to ensure proper failover
openshift_clock_enabled=true

# host group for masters
[masters]
master1.example.com
master2.example.com
master3.example.com

# host group for etcd
[etcd]
etcd1.example.com
etcd2.example.com
etcd3.example.com

# Specify load balancer host
[lb]
lb.example.com

# host group for nodes, includes region info
[nodes]
master[1:3].example.com openshift_node_group_name=‘node-config-master‘
node1.example.com openshift_node_group_name=‘node-config-compute‘
node1.example.com openshift_node_group_name=‘node-config-compute‘
infra-node1.example.com openshift_node_group_name=‘node-config-infra‘
infra-node2.example.com openshift_node_group_name=‘node-config-infra‘

1. Multiple Masters Using Native HA with Co-located Clustered etcd

# Create an OSEv3 group that contains the master, nodes, etcd, and lb groups.
# The lb group lets Ansible configure HAProxy as the load balancing solution.
# Comment lb out if your load balancer is pre-configured.
[OSEv3:children]
masters
nodes
etcd
lb

# Set variables common for all OSEv3 hosts
[OSEv3:vars]
ansible_ssh_user=root
openshift_deployment_type=origin

# uncomment the following to enable htpasswd authentication; defaults to AllowAllPasswordIdentityProvider
#openshift_master_identity_providers=[{‘name‘: ‘htpasswd_auth‘, ‘login‘: ‘true‘, ‘challenge‘: ‘true‘, ‘kind‘: ‘HTPasswdPasswordIdentityProvider‘}]

# Native high availability cluster method with optional load balancer.
# If no lb group is defined installer assumes that a load balancer has
# been preconfigured. For installation the value of
# openshift_master_cluster_hostname must resolve to the load balancer
# or to one or all of the masters defined in the inventory if no load
# balancer is present.
openshift_master_cluster_method=native
openshift_master_cluster_hostname=openshift-internal.example.com
openshift_master_cluster_public_hostname=openshift-cluster.example.com

# host group for masters
[masters]
master1.example.com
master2.example.com
master3.example.com

# host group for etcd
[etcd]
master1.example.com
master2.example.com
master3.example.com

# Specify load balancer host
[lb]
lb.example.com

# host group for nodes, includes region info
[nodes]
master[1:3].example.com openshift_node_group_name=‘node-config-master‘
node1.example.com openshift_node_group_name=‘node-config-compute‘
node1.example.com openshift_node_group_name=‘node-config-compute‘
infra-node1.example.com openshift_node_group_name=‘node-config-infra‘
infra-node2.example.com openshift_node_group_name=‘node-config-infra‘

1. ELB Load Balancer

使用外部ELB,不需定义lb，需要指定openshift_master_cluster_hostname、openshift_master_cluster_public_hostname、openshift_master_default_subdomain。

# Create an OSEv3 group that contains the master, nodes, etcd, and lb groups.
# The lb group lets Ansible configure HAProxy as the load balancing solution.
# Comment lb out if your load balancer is pre-configured.
[OSEv3:children]
masters
nodes
etcd
# Since we are providing a pre-configured LB VIP, no need for this group
#lb

# Set variables common for all OSEv3 hosts
[OSEv3:vars]
# SSH user, this user should allow ssh based auth without requiring a password
ansible_ssh_user=ec2-user

# If ansible_ssh_user is not root, ansible_become must be set to true
ansible_become=true

openshift_deployment_type=origin
openshift_disable_check=disk_availability,docker_storage,memory_availability,docker_image_availability

# uncomment the following to enable htpasswd authentication; defaults to DenyAllPasswordIdentityProvider
openshift_master_identity_providers=[{‘name‘: ‘htpasswd_auth‘, ‘login‘: ‘true‘, ‘challenge‘: ‘true‘, ‘kind‘: ‘HTPasswdPasswordIdentityProvider‘}]
# Defining htpasswd users
#openshift_master_htpasswd_users={‘user1‘: ‘<pre-hashed password>‘, ‘user2‘: ‘<pre-hashed password>‘
# or
#openshift_master_htpasswd_file=<path to local pre-generated htpasswd file>

# Native high availability cluster method with optional load balancer.
# If no lb group is defined installer assumes that a load balancer has
# been preconfigured. For installation the value of
# openshift_master_cluster_hostname must resolve to the load balancer
# or to one or all of the masters defined in the inventory if no load
# balancer is present.
openshift_master_cluster_method=native
openshift_master_cluster_hostname=openshift-master-internal-123456b57ac7be6c.elb.cn-north-1.amazonaws.com.cn
openshift_master_cluster_public_hostname=openshift.itrunner.org
openshift_master_default_subdomain=apps.itrunner.org
#openshift_master_api_port=443
#openshift_master_console_port=443

# host group for masters
[masters]
master1.itrunner.org
master2.itrunner.org
master3.itrunner.org

# host group for etcd
[etcd]
master1.itrunner.org
master2.itrunner.org
master3.itrunner.org

# Since we are providing a pre-configured LB VIP, no need for this group
#[lb]
#lb.itrunner.org

# host group for nodes, includes region info
[nodes]
master[1:3].itrunner.org openshift_node_group_name=‘node-config-master‘
node1.itrunner.org openshift_node_group_name=‘node-config-compute‘
node1.itrunner.org openshift_node_group_name=‘node-config-compute‘
infra-node1.itrunner.org openshift_node_group_name=‘node-config-infra‘
infra-node2.itrunner.org openshift_node_group_name=‘node-config-infra‘

安装OpenShift

一切准备就绪，使用ansible安装OpenShift非常简单，仅需运行prerequisites.yml和deploy_cluster.yml两个playbook。

$ ansible-playbook ~/openshift-ansible/playbooks/prerequisites.yml
$ ansible-playbook ~/openshift-ansible/playbooks/deploy_cluster.yml

如没有使用默认的inventory文件，可以使用-i指定文件位置：

$ ansible-playbook [-i /path/to/inventory] ~/openshift-ansible/playbooks/prerequisites.yml
$ ansible-playbook [-i /path/to/inventory] ~/openshift-ansible/playbooks/deploy_cluster.yml

deploy过程中如出现错误，修正后可以运行提示中的playbook测试，然后再运行deploy_cluster.yml。

验证安装

1. 验证所有结点是否成功安装，在Master上运行：

# oc get nodes

1. 验证Web Console

场景一，使用master hostname访问web console: https://master1.itrunner.org:8443/console
场景二，使用域名访问web console: https://openshift.itrunner.org:8443/console

用户与权限

创建两个用户：

# htpasswd /etc/origin/master/htpasswd admin
# htpasswd /etc/origin/master/htpasswd developer

使用system:admin登录：

# oc login -u system:admin

用户授权：

# oc adm policy add-cluster-role-to-user cluster-admin admin
# oc adm policy add-role-to-user admin admin

CLI配置文件
oc login命令自动创建和管理CLI配置文件~/.kube/config。

卸载OpenShift

• 卸载所有Node

使用安装时的inventory文件

$ ansible-playbook ~/openshift-ansible/playbooks/adhoc/uninstall.yml

• 卸载部分Node

新建一个inventory文件，配置要卸载的node:

[OSEv3:children]
nodes 

[OSEv3:vars]
ansible_ssh_user=ec2-user
openshift_deployment_type=origin

[nodes]
node3.example.com openshift_node_group_name=‘node-config-infra‘

指定新的inventory文件，运行uninstall.yml playbook：

$ ansible-playbook -i /path/to/new/file ~/openshift-ansible/playbooks/adhoc/uninstall.yml

参考资料

OpenShift
OpenShift Github
OpenShift Documentation
OKD
OKD Latest Documentation
Ansible Documentation
External Load Balancer Integrations with OpenShift Enterprise 3
Red Hat OpenShift on AWS
Docker Documentation
Kubernetes Documentation
Kubernetes中文社区
Kubernetes-基于EFK进行统一的日志管理
SSL For Free

原文地址：http://blog.51cto.com/7308310/2171091