Terraform 基础

Terraform 是 HashiCorp 开发的基础设施即代码（Infrastructure as Code, IaC）工具，使用声明式配置语言 HCL（HashiCorp Configuration Language）来定义和管理云资源。通过 Terraform，你可以用代码描述完整的基础设施架构，实现版本控制和可重复部署。

安装 Terraform

通过官方仓库安装

通过官方仓库安装（EL 9 / EL 10）

# 安装 DNF 插件（提供 config-manager）
sudo dnf install -y dnf-plugins-core

# 添加 HashiCorp 官方仓库
sudo dnf config-manager --add-repo https://rpm.releases.hashicorp.com/RHEL/hashicorp.repo

# 安装 Terraform
sudo dnf install -y terraform

# 验证安装
terraform version

手动安装

# 下载最新版本（访问 https://developer.hashicorp.com/terraform/install 确认最新版本号）
TERRAFORM_VERSION="1.9.0"  # 示例版本，请替换为官网最新版本号
wget https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip

# 解压并安装
sudo dnf install -y unzip
unzip terraform_${TERRAFORM_VERSION}_linux_amd64.zip
sudo mv terraform /usr/local/bin/
sudo chmod +x /usr/local/bin/terraform

# 验证
terraform version

启用命令自动补全

# 安装自动补全
terraform -install-autocomplete

# 重新加载 shell
source ~/.bashrc

HCL 语法基础

Terraform 配置文件使用 .tf 扩展名，采用 HCL 语法。

基本结构

# 注释以 # 开头

# 块（Block）结构
resource "类型" "名称" {
  参数1 = "值1"
  参数2 = 123

  # 嵌套块
  nested_block {
    key = "value"
  }
}

# 字符串插值
variable "name" {
  default = "myserver"
}

resource "example" "demo" {
  name = "prefix-${var.name}"
}

数据类型

# 字符串
name = "web-server"

# 数字
count = 3

# 布尔值
enabled = true

# 列表
availability_zones = ["cn-hangzhou-a", "cn-hangzhou-b"]

# 映射（Map）
tags = {
  Name        = "web-server"
  Environment = "production"
  Team        = "ops"
}

Provider 配置

Provider 是 Terraform 与云平台交互的插件。

AWS 示例

providers.tf

terraform {
  required_version = ">= 1.5.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region     = "ap-northeast-1"  # 东京区域
  access_key = var.aws_access_key
  secret_key = var.aws_secret_key

  # 或者使用环境变量（推荐）：
  # export AWS_ACCESS_KEY_ID="your-access-key"
  # export AWS_SECRET_ACCESS_KEY="your-secret-key"
}

阿里云示例

providers.tf

terraform {
  required_version = ">= 1.5.0"

  required_providers {
    alicloud = {
      source  = "aliyun/alicloud"
      version = "~> 1.220"
    }
  }
}

provider "alicloud" {
  region     = "cn-hangzhou"
  access_key = var.alicloud_access_key
  secret_key = var.alicloud_secret_key
}

创建资源

AWS EC2 实例示例

# variables.tf - 变量定义
variable "aws_access_key" {
  description = "AWS Access Key"
  type        = string
  sensitive   = true
}

variable "aws_secret_key" {
  description = "AWS Secret Key"
  type        = string
  sensitive   = true
}

variable "instance_type" {
  description = "EC2 实例类型"
  type        = string
  default     = "t3.micro"
}

variable "instance_count" {
  description = "实例数量"
  type        = number
  default     = 1
}

# main.tf - 主配置文件
# 查询最新的 AlmaLinux 9 AMI
data "aws_ami" "almalinux9" {
  most_recent = true
  owners      = ["764336703387"]  # AlmaLinux 官方

  filter {
    name   = "name"
    values = ["AlmaLinux OS 9*x86_64*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }
}

# 创建安全组
resource "aws_security_group" "web" {
  name        = "web-sg"
  description = "Allow HTTP and SSH"

  ingress {
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
    description = "SSH"
  }

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
    description = "HTTP"
  }

  ingress {
    from_port   = 443
    to_port     = 443
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
    description = "HTTPS"
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }

  tags = {
    Name = "web-security-group"
  }
}

# 创建 EC2 实例
resource "aws_instance" "web" {
  count         = var.instance_count
  ami           = data.aws_ami.almalinux9.id
  instance_type = var.instance_type

  vpc_security_group_ids = [aws_security_group.web.id]

  user_data = <<-EOF
    #!/bin/bash
    dnf install -y nginx
    systemctl enable --now nginx
    echo "<h1>Server ${count.index + 1}</h1>" > /usr/share/nginx/html/index.html
  EOF

  tags = {
    Name = "web-server-${count.index + 1}"
    Env  = "production"
  }
}

# outputs.tf - 输出定义
output "instance_public_ips" {
  description = "实例公网 IP 列表"
  value       = aws_instance.web[*].public_ip
}

output "instance_ids" {
  description = "实例 ID 列表"
  value       = aws_instance.web[*].id
}

output "ami_id" {
  description = "使用的 AMI ID"
  value       = data.aws_ami.almalinux9.id
}

阿里云 ECS 实例示例

# main.tf - 阿里云 ECS 示例
variable "alicloud_access_key" {
  type      = string
  sensitive = true
}

variable "alicloud_secret_key" {
  type      = string
  sensitive = true
}

# 查询可用区
data "alicloud_zones" "default" {
  available_resource_creation = "VSwitch"
}

# 查询镜像
data "alicloud_images" "almalinux" {
  name_regex  = "^almalinux_9"
  most_recent = true
  owners      = "system"
}

# 创建 VPC
resource "alicloud_vpc" "main" {
  vpc_name   = "tf-demo-vpc"
  cidr_block = "172.16.0.0/16"
}

# 创建交换机
resource "alicloud_vswitch" "main" {
  vswitch_name = "tf-demo-vsw"
  vpc_id       = alicloud_vpc.main.id
  cidr_block   = "172.16.1.0/24"
  zone_id      = data.alicloud_zones.default.zones[0].id
}

# 创建安全组
resource "alicloud_security_group" "web" {
  name   = "tf-demo-sg"
  vpc_id = alicloud_vpc.main.id
}

resource "alicloud_security_group_rule" "allow_ssh" {
  type              = "ingress"
  ip_protocol       = "tcp"
  port_range        = "22/22"
  security_group_id = alicloud_security_group.web.id
  cidr_ip           = "0.0.0.0/0"
}

resource "alicloud_security_group_rule" "allow_http" {
  type              = "ingress"
  ip_protocol       = "tcp"
  port_range        = "80/80"
  security_group_id = alicloud_security_group.web.id
  cidr_ip           = "0.0.0.0/0"
}

# 创建 ECS 实例
resource "alicloud_instance" "web" {
  instance_name        = "tf-demo-ecs"
  image_id             = data.alicloud_images.almalinux.images[0].id
  instance_type        = "ecs.t6-c1m1.large"
  security_groups      = [alicloud_security_group.web.id]
  vswitch_id           = alicloud_vswitch.main.id
  internet_max_bandwidth_out = 10
  system_disk_size     = 40

  user_data = base64encode(<<-EOF
    #!/bin/bash
    dnf install -y nginx
    systemctl enable --now nginx
  EOF
  )

  tags = {
    Name = "web-server"
    Env  = "demo"
  }
}

output "public_ip" {
  value = alicloud_instance.web.public_ip
}

Plan / Apply / Destroy 工作流

初始化项目

# 进入项目目录
cd /opt/terraform/myproject

# 初始化（下载 Provider 插件）
terraform init

# 升级 Provider 版本
terraform init -upgrade

查看执行计划

# 查看计划（预览将要执行的变更）
terraform plan

# 将计划保存到文件
terraform plan -out=tfplan

# 使用变量文件
terraform plan -var-file="production.tfvars"

# 传递单个变量
terraform plan -var="instance_count=3"

应用变更

# 应用变更（会要求确认）
terraform apply

# 使用保存的计划文件（无需确认）
terraform apply tfplan

# 自动确认（用于 CI/CD）
terraform apply -auto-approve

# 使用变量文件
terraform apply -var-file="production.tfvars"

销毁资源

# 销毁所有资源
terraform destroy

# 自动确认销毁
terraform destroy -auto-approve

# 仅销毁指定资源
terraform destroy -target=aws_instance.web

其他常用命令

# 格式化配置文件
terraform fmt

# 递归格式化
terraform fmt -recursive

# 验证配置语法
terraform validate

# 查看当前状态
terraform show

# 列出所有资源
terraform state list

# 查看特定资源的详细信息
terraform state show aws_instance.web[0]

# 刷新状态（同步远端实际状态）
terraform refresh

# 生成依赖关系图
terraform graph | dot -Tpng > graph.png

变量文件

使用 .tfvars 文件管理不同环境的变量：

production.tfvars

instance_type  = "t3.large"
instance_count = 3

staging.tfvars

instance_type  = "t3.micro"
instance_count = 1

# 使用不同环境的变量
terraform apply -var-file="production.tfvars"
terraform apply -var-file="staging.tfvars"

通过环境变量传递敏感信息：

# Terraform 会自动读取 TF_VAR_ 前缀的环境变量
export TF_VAR_aws_access_key="AKIAIOSFODNN7EXAMPLE"
export TF_VAR_aws_secret_key="wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"

terraform apply

State 状态管理

Terraform 状态文件（terraform.tfstate）记录了基础设施的当前状态。在团队协作中，应使用远程后端存储状态文件。

本地状态（默认）

# 状态文件位于项目目录
ls -la terraform.tfstate
ls -la terraform.tfstate.backup

远程状态 - S3 后端

terraform {
  backend "s3" {
    bucket         = "my-terraform-state"
    key            = "production/terraform.tfstate"
    region         = "ap-northeast-1"
    encrypt        = true
    dynamodb_table = "terraform-lock"  # 状态锁定
  }
}

远程状态 - 阿里云 OSS 后端

terraform {
  backend "oss" {
    bucket   = "my-terraform-state"
    prefix   = "production"
    region   = "cn-hangzhou"
    encrypt  = true

    tablestore_endpoint = "https://tf-state-lock.cn-hangzhou.ots.aliyuncs.com"
    tablestore_table    = "terraform-lock"
  }
}

状态操作

# 列出状态中的资源
terraform state list

# 查看资源详情
terraform state show aws_instance.web[0]

# 移动资源（重命名）
terraform state mv aws_instance.web aws_instance.webserver

# 从状态中移除资源（不删除实际资源）
terraform state rm aws_instance.web[0]

# 导入已有资源到 Terraform 管理
terraform import aws_instance.web i-0abc123def456

# 拉取远程状态
terraform state pull > state.json

# 推送状态到远端
terraform state push state.json

基础模块

模块（Module）用于封装和复用 Terraform 配置。

创建模块

# 模块目录结构
mkdir -p modules/ecs-instance

modules/ecs-instance/variables.tf

variable "instance_name" {
  description = "实例名称"
  type        = string
}

variable "instance_type" {
  description = "实例规格"
  type        = string
  default     = "ecs.t6-c1m1.large"
}

variable "image_id" {
  description = "镜像 ID"
  type        = string
}

variable "vswitch_id" {
  description = "交换机 ID"
  type        = string
}

variable "security_group_id" {
  description = "安全组 ID"
  type        = string
}

variable "tags" {
  description = "资源标签"
  type        = map(string)
  default     = {}
}

modules/ecs-instance/main.tf

resource "alicloud_instance" "this" {
  instance_name              = var.instance_name
  instance_type              = var.instance_type
  image_id                   = var.image_id
  vswitch_id                 = var.vswitch_id
  security_groups            = [var.security_group_id]
  internet_max_bandwidth_out = 10
  system_disk_size           = 40
  tags                       = var.tags
}

modules/ecs-instance/outputs.tf

output "instance_id" {
  value = alicloud_instance.this.id
}

output "public_ip" {
  value = alicloud_instance.this.public_ip
}

output "private_ip" {
  value = alicloud_instance.this.private_ip
}

调用模块

# main.tf - 使用自定义模块
module "web_server" {
  source = "./modules/ecs-instance"

  instance_name     = "web-server-01"
  instance_type     = "ecs.t6-c1m1.large"
  image_id          = data.alicloud_images.almalinux.images[0].id
  vswitch_id        = alicloud_vswitch.main.id
  security_group_id = alicloud_security_group.web.id

  tags = {
    Role = "web"
    Env  = "production"
  }
}

module "api_server" {
  source = "./modules/ecs-instance"

  instance_name     = "api-server-01"
  instance_type     = "ecs.c6.large"
  image_id          = data.alicloud_images.almalinux.images[0].id
  vswitch_id        = alicloud_vswitch.main.id
  security_group_id = alicloud_security_group.web.id

  tags = {
    Role = "api"
    Env  = "production"
  }
}

output "web_server_ip" {
  value = module.web_server.public_ip
}

output "api_server_ip" {
  value = module.api_server.public_ip
}

使用远程模块

# 使用 Terraform Registry 上的模块
module "vpc" {
  source  = "alibaba/vpc/alicloud"
  version = "1.10.0"

  vpc_name   = "production-vpc"
  vpc_cidr   = "10.0.0.0/8"
}

推荐的项目结构

terraform-project/
├── environments/
│   ├── production/
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   ├── outputs.tf
│   │   ├── terraform.tfvars
│   │   └── backend.tf
│   └── staging/
│       ├── main.tf
│       ├── variables.tf
│       ├── outputs.tf
│       ├── terraform.tfvars
│       └── backend.tf
├── modules/
│   ├── ecs-instance/
│   ├── vpc/
│   └── security-group/
└── .gitignore

为 Terraform 项目创建 .gitignore：

cat > .gitignore << 'EOF'
# Terraform
.terraform/
*.tfstate
*.tfstate.backup
*.tfplan
*.tfvars
!example.tfvars

# 敏感文件
*.pem
*.key
EOF

Terraform 是基础设施即代码的核心工具，将云资源的创建和管理纳入版本控制。配合 Cloud-Init 传入 user-data 和 Ansible 进行后续配置，三者共同构建出完整的自动化基础设施交付流水线。