阿里云平台下Terraform+Packer一键部署WordPress案例

前言

前面 云生态下的基础架构资源管理利器Terraform 一文对Terraform做了产品介绍，包括安装、模板配置文件编写，资源构建与销毁等。这里通过介绍Terraform + Packer 在阿里云平台上一键部署WordPress的案例，以供大家使用参考，也欢迎一起参与讨论。

该实现方案包括完成阿里云资源购买创建，到应用部署，配置修改，启动服务，最终交付一个WordPress的公网可访问IP地址。并且通过简单修改Terraform的模板配置文件ECS资源count数可实现弹性扩容（自动添加挂载到SLB）。

Packer构建VM镜像

Packer是一款面向云生态非常便利的镜像管理利器，通过一个模板配置可以快速的创建镜像。这里不做具体介绍，可阅读前面写的 云生态下的镜像管理利器Packer 一文了解整个VM镜像构建的过程。

这里我们先来看下该案例中一键构建WordPress的镜像模板JSON文件：

{
  "variables": {
    "access_key": "${your_access_key}",
    "secret_key": "${your_secret_key}"
  },
  "builders": [{
    "type":"alicloud-ecs",
    "access_key":"${your_access_key}",
    "secret_key":"${your_secret_key}",
    "region":"cn-beijing",
    "image_name":"packer_test_image",
    "source_image":"centos_7_03_64_20G_alibase_20170818.vhd",
    "ssh_username":"root",
    "instance_type":"ecs.n4.small",
    "internet_charge_type":"PayByTraffic",
    "io_optimized":"true"
  }],
  "provisioners": [{
    "type": "file",
    "source": "wordpress_init.sh",
    "destination": "/tmp/"
    },{
    "type": "shell",
    "inline": [
      "sleep 30",
      "cd /tmp",
      "sudo chmod 755 wordpress_init.sh",
      "./wordpress_init.sh"
    ]
  }]
}

这里我们引用阿里云的基础镜像：
"source_image":"centos_7_03_64_20G_alibase_20170818.vhd"
此外，还定义了一个WordPress应用环境初始化的shell脚本wordpress_init.sh，这里表示创建镜像过程中，把本地的wordpress_init.sh远程拷贝到临时的VM上，并执行该脚本，如下为wordpress_init.sh的内容：

#!/bin/bash

wordpress_url="https://cn.wordpress.org/wordpress-4.8.1-zh_CN.tar.gz"

# install httpd & php & php-mysql & wget
if grep -Eqi "Ubuntu|Debian|Raspbian" /etc/issue || grep -Eq "Ubuntu|Debian|Raspbian" /etc/*-release; then
        sudo apt-get update -y
        sudo apt-get install -y httpd
        sudo apt-get install -y php
        sudo apt-get install -y php-mysql
        sudo apt-get install -y wget
elif grep -Eqi "CentOS|Fedora|Red Hat Enterprise Linux Server" /etc/issue || grep -Eq "CentOS|Fedora|Red Hat Enterprise Linux Server" /etc/*-release; then
        sudo yum update -y
        sudo yum install -y httpd
        sudo yum install -y php
        sudo yum install -y php-mysql
        sudo yum install -y wget
else
        echo "Unknown OS type."
fi

# download wordpress pkg & configure wordpress
cd /root/
wget ${wordpress_url}
mkdir -p /var/www/html/
tar zxf wordpress-4.8.1-zh_CN.tar.gz -C /var/www/html/
cd /var/www/html/wordpress/
cp wp-config-sample.php wp-config.php
useradd apache
chown apache:apache /var/www/html/wordpress/

该脚本通过安装WordPress依赖的应用软件包，以及创建账号信息，最终我们想要获取的则为一个私有自定义镜像。

将模板配置文件和wordpress_init.sh脚本文件放置在同一个目录下，通过$ packer build ${template_json_file} 即可完成自定义镜像文件的创建：

Terraform 创建云资源

构建完预安装好WordPress依赖软件包的镜像后，我们就可以开始编写Terraform的资源构建模板文件里，如下的架构图：

这里将划分一个VPC私网，初始购买2台VM，挂载在一个开放公网IP的SLB下，后端数据持久化到RDS，并配置SNAT出公网的路由，同时支持一键扩容无个数限制的VM。

对于Terraform模板配置文件主要分3个：

• 主配置文件 （定义创建的resource）
• 变量配置文件 （定义主配置文件中指定的variables）
• 输出配置文件 （定义terraform build执行完输出的信息）

Terraform 主配置文件

provider "alicloud" {
  access_key = "${var.access_key}"
  secret_key = "${var.secret_key}"
  region = "${var.region}"
}

resource "alicloud_security_group" "sg" {
  name   = "terraform-sg"
  vpc_id = "${alicloud_vpc.vpc.id}"
}

resource "alicloud_security_group_rule" "allow_http" {
  type              = "ingress"
  ip_protocol       = "tcp"
  nic_type          = "intranet"
  policy            = "accept"
  port_range        = "80/80"
  priority          = 1
  security_group_id = "${alicloud_security_group.sg.id}"
  cidr_ip           = "0.0.0.0/0"
}

resource "alicloud_security_group_rule" "allow_ssh" {
  type              = "ingress"
  ip_protocol       = "tcp"
  nic_type          = "intranet"
  policy            = "accept"
  port_range        = "22/22"
  priority          = 2
  security_group_id = "${alicloud_security_group.sg.id}"
  cidr_ip           = "0.0.0.0/0"
}

resource "alicloud_vpc" "vpc" {
  name = "terraform-vpc"
  cidr_block = "192.168.0.0/16"
}

resource "alicloud_vswitch" "vsw" {
  vpc_id            = "${alicloud_vpc.vpc.id}"
  cidr_block        = "192.168.1.0/24"
  availability_zone = "${var.zone}"
}

resource "alicloud_nat_gateway" "nat_gateway" {
  vpc_id = "${alicloud_vpc.vpc.id}"
  spec   = "Small"
  name   = "wordpress_nat_gateway"

  bandwidth_packages = [{
    ip_count  = 1
    bandwidth = 5
  }]

  depends_on = [
    "alicloud_vswitch.vsw",
  ]
}

resource "alicloud_snat_entry" "foo" {
  snat_table_id     = "${alicloud_nat_gateway.nat_gateway.snat_table_ids}"
  source_vswitch_id = "${alicloud_vswitch.vsw.id}"
  snat_ip           = "${alicloud_nat_gateway.nat_gateway.bandwidth_packages.0.public_ip_addresses}"
}

resource "alicloud_slb" "slb" {
  name       = "wordpress-slb-tf"
  internet   = true
  internet_charge_type = "paybytraffic"

  listener = [ 
    {   
      "instance_port" = "80"
      "lb_port"       = "80"
      "lb_protocol"   = "tcp"
      "bandwidth"     = "10"
      "sticky_session" = "on"
      "sticky_session_type" = "insert"
      "cookie_timeout" = "1" 
      "health_check"  = "on"
      "health_check_type" = "tcp"
      "health_check_connect_port" = "80"
    }   
  ]

}

resource "alicloud_slb_attachment" "slb_attachment" {
  slb_id    = "${alicloud_slb.slb.id}"
  instances = ["${alicloud_instance.web.*.id}"]
}

resource "alicloud_instance" "web" {
  count = "${var.count}"
  instance_name = "${var.short_name}-${var.role}-${format(var.count_format, count.index+1)}"
  host_name = "${var.short_name}-${var.role}-${format(var.count_format, count.index+1)}"
  password = "${var.ecs_password}"
  availability_zone = "${var.zone}"
  image_id = "${var.image_id}"
  instance_type = "ecs.n4.small"
  io_optimized = "optimized"
  system_disk_category = "cloud_efficiency"
  security_groups = ["${alicloud_security_group.sg.id}"]
  vswitch_id = "${alicloud_vswitch.vsw.id}"
  user_data = "#!/bin/bash\nsed -i 's/database_name_here/${var.database_name}/g' /var/www/html/wordpress/wp-config.php\nsed -i 's/username_here/${var.database_user_name}/g' /var/www/html/wordpress/wp-config.php\nsed -i 's/password_here/${var.database_user_password}/g' /var/www/html/wordpress/wp-config.php\nsed -i 's/localhost/${alicloud_db_instance.rds.connections.0.connection_string}/g' /var/www/html/wordpress/wp-config.php\nsed -i 's/utf8/utf8mb4/g' /var/www/html/wordpress/wp-config.php\nservice httpd stop\nservice httpd start" 
  depends_on = ["alicloud_db_instance.rds"]
}

resource "alicloud_db_instance" "rds" {
    engine = "MySQL"
    engine_version = "5.6"
    db_instance_class = "rds.mysql.t1.small"
    db_instance_storage = "10"
    db_instance_net_type = "Intranet"
    vswitch_id = "${alicloud_vswitch.vsw.id}"
    security_ips  = ["192.168.1.0/24"]

    master_user_name = "${var.database_user_name}"
    master_user_password = "${var.database_user_password}"

    db_mappings = [{
      db_name = "${var.database_name}"
      character_set_name = "${var.database_character}"
      db_description = "terraform wordpress"
    }]
}

如上主配置文件定义了VPC和VSwitch，ECS和安全组（带规则），SLB和挂载节点、VM个数等资源信息：

  + alicloud_db_instance.rds
  + alicloud_instance.web[0]
  + alicloud_instance.web[1]
  + alicloud_nat_gateway.nat_gateway
  + alicloud_security_group.sg
  + alicloud_security_group_rule.allow_http
  + alicloud_security_group_rule.allow_ssh
  + alicloud_slb.slb
  + alicloud_slb_attachment.slb_attachment
  + alicloud_snat_entry.foo
  + alicloud_vpc.vpc
  + alicloud_vswitch.vsw

其中user_data 部分对wordpresss数据库连接信息做了格式化，需要留意的地方是该resource依赖alicloud_db_instance.rds 信息，故必须指定depends_on参数。

Terraform 变量配置文件

variable "count" {
  default = "2"
}
variable "access_key" {
  default = "{your_access_key}"
}
variable "secret_key" {
  default = "{your_secret_key}"
}
variable "region" {
  default = "cn-beijing"
}
variable "zone" {
  default = "cn-beijing-a"
}
variable "ecs_password" {
  default = "${ecs_password}"
}
variable "database_user_name" {
  default = "wordpress"
}
variable "database_user_password" {
  default = "${database_user_password}"
}
variable "database_name" {
  default = "wordpress"
}
variable "database_character" {
  default = "utf8"
}
variable "count_format" {
  default = "%02d"
}
variable "image_id" {
  default = "m-2zeapruq86du81hz56kb"
}
variable "availability_zones" {
  default = ""
}
variable "role" {
  default = "web"
}
variable "datacenter" {
  default = "beijing"
}
variable "short_name" {
  default = "wordpress"
}
variable "ecs_type" {
  default = "ecs.n4.small"
}
variable "allocate_public_ip" {
  default = true
}
variable "internet_charge_type" {
  default = "PayByTraffic"
}
variable "internet_max_bandwidth_out" {
  default = 5
}
variable "disk_category" {
  default = "cloud_efficiency"
}
variable "disk_size" {
  default = "40"
}
variable "nic_type" {
  default = "internet"
}

如上变量配置信息，关键需要把前面通过Packer创建的镜像ID填写进去：

variable "image_id" {
  default = "m-2zeapruq86du81hz56kb"
}

Terraform 输出配置文件

output "address" {
  value = "${alicloud_slb.slb.address}"
}

output "rds_connection_string" {
    value = "${alicloud_db_instance.rds.connections.0.connection_string}"
}

对于输出信息，主要需要获取SLB的公网IP，通过该IP访问WordPress应用。

执行创建和验证

确保如上的三个Terraform配置文件放置于同一个目录下，通过运行$ terraform apply，等待个10分钟则可创建完成。

wangzhipengs-MacBook-Pro:wordpress4_packer wangzhipeng$ terraform apply
alicloud_vpc.vpc: Creating...
  cidr_block:      "" => "192.168.0.0/16"
  name:            "" => "terraform-vpc"
  router_id:       "" => "<computed>"
  router_table_id: "" => "<computed>"
alicloud_slb.slb: Creating...
  address:                                       "" => "<computed>"
  bandwidth:                                     "" => "<computed>"
  internet:                                      "" => "true"
  internet_charge_type:                          "" => "paybytraffic"
  listener.#:                                    "" => "1"
  listener.3892906561.bandwidth:                 "" => "10"
...（中间省略部分输出信息）

alicloud_slb_attachment.slb_attachment: Creation complete after 1s (ID: lb-2zeh8m9c6okymqk6bb2xz)

Apply complete! Resources: 12 added, 0 changed, 0 destroyed.

Outputs:

address = 47.95.95.152
rds_connection_string = rm-2ze57t716g530c19r.mysql.rds.aliyuncs.com

通过访问 http://47.95.95.152/wordpress 完成下基础配置，WordPress就搭建完成了。

总结

综上，为实现在阿里云平台下Terraform+Packer一键部署WordPress，除了定义Packer的镜像配置文件，还需要定义好Terraform 资源模板文件。这里所体现的就是Infrastructure as Code的思想，一次编写可多次运行，所有构建的资源都状态化，也方便我们对资源进行有效管理，比如资源扩容、资源销毁等。

回到这个案例，前面Packer 和 Terraform 配置文件的准备工作就绪，我们只需要做的，就是一条terraform apply指令则可轻松构建一个WordPress应用。