Terraform的使用
1. 安装terraform
mac
brew tap hashicorp/tap
brew install hashicorp/tap/terraform
linux: centos
sudo yum install -y yum-utils
sudo yum-config-manager --add-repo https://rpm.releases.hashicorp.com/RHEL/hashicorp.repo
sudo yum -y install terraform
2. terraform命令
编写terraform的部署文本，常用命令：
-
terraform init：项目初始化
-
terraform plan：预览
-
terraform apply：部署
-
terraform destroy：销毁
terraform --help
Usage: terraform [global options] <subcommand> [args]
The available commands for execution are listed below.
The primary workflow commands are given first, followed by
less common or more advanced commands.
Main commands:
init Prepare your working directory for other commands
validate Check whether the configuration is valid
plan Show changes required by the current configuration
apply Create or update infrastructure
destroy Destroy previously-created infrastructure
All other commands:
console Try Terraform expressions at an interactive command prompt
fmt Reformat your configuration in the standard style
force-unlock Release a stuck lock on the current workspace
get Install or upgrade remote Terraform modules
graph Generate a Graphviz graph of the steps in an operation
import Associate existing infrastructure with a Terraform resource
login Obtain and save credentials for a remote host
logout Remove locally-stored credentials for a remote host
metadata Metadata related commands
modules Show all declared modules in a working directory
output Show output values from your root module
providers Show the providers required for this configuration
refresh Update the state to match remote systems
show Show the current state or a saved plan
stacks Manage HCP Terraform stack operations
state Advanced state management
taint Mark a resource instance as not fully functional
test Execute integration tests for Terraform modules
untaint Remove the 'tainted' state from a resource instance
version Show the current Terraform version
workspace Workspace management
3. 通过terraform部署k8s应用
3.1. 创建部署文件
创建应用目录，并在本地创建main.tf文件。
terraform {
required_providers {
kubernetes = {
source = "hashicorp/kubernetes"
version = ">= 2.0.0"
}
}
}
provider "kubernetes" {
config_path = "~/.kube/config"
}
resource "kubernetes_namespace" "test" {
metadata {
name = "nginx"
}
}
resource "kubernetes_deployment" "test" {
metadata {
name = "nginx"
namespace = kubernetes_namespace.test.metadata.0.name
}
spec {
replicas = 2
selector {
match_labels = {
app = "MyTestApp"
}
}
template {
metadata {
labels = {
app = "MyTestApp"
}
}
spec {
container {
image = "nginx"
name = "nginx-container"
port {
container_port = 80
}
}
}
}
}
}
resource "kubernetes_service" "test" {
metadata {
name = "nginx"
namespace = kubernetes_namespace.test.metadata.0.name
}
spec {
selector = {
app = kubernetes_deployment.test.spec.0.template.0.metadata.0.labels.app
}
type = "NodePort"
port {
node_port = 30201
port = 80
target_port = 80
}
}
}
3.2. 执行部署命令
- terraform init
初始化terraform provider数据。
- terraform plan
部署之前预览diff数据。
# terraform plan
Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
+ create
Terraform will perform the following actions:
# kubernetes_deployment.test will be created
+ resource "kubernetes_deployment" "test" {
+ id = (known after apply)
+ wait_for_rollout = true
+ metadata {
+ generation = (known after apply)
+ name = "nginx"
+ namespace = "nginx"
+ resource_version = (known after apply)
+ uid = (known after apply)
}
+ spec {
+ min_ready_seconds = 0
+ paused = false
+ progress_deadline_seconds = 600
+ replicas = "2"
+ revision_history_limit = 10
....
Plan: 3 to add, 0 to change, 0 to destroy.
──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take exactly these actions if you run "terraform apply" now.
- terraform apply
执行部署的操作。
# terraform apply
Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
+ create
Terraform will perform the following actions:
# kubernetes_deployment.test will be created
+ resource "kubernetes_deployment" "test" {
+ id = (known after apply)
+ wait_for_rollout = true
...
Plan: 3 to add, 0 to change, 0 to destroy.
Do you want to perform these actions?
Terraform will perform the actions described above.
Only 'yes' will be accepted to approve.
Enter a value: yes
kubernetes_namespace.test: Creating...
kubernetes_namespace.test: Creation complete after 0s [id=nginx]
kubernetes_deployment.test: Creating...
kubernetes_deployment.test: Creation complete after 4s [id=nginx/nginx]
kubernetes_service.test: Creating...
kubernetes_service.test: Creation complete after 0s [id=nginx/nginx]
Apply complete! Resources: 3 added, 0 changed, 0 destroyed.
查看部署结果
terraform共创建了三个资源，即对应k8s的三个对象：namespace，deployment，service。
# kubectl get all -n nginx
NAME READY STATUS RESTARTS AGE
pod/nginx-658c56bc8-djhrx 1/1 Running 0 30m
pod/nginx-658c56bc8-mh67k 1/1 Running 0 30m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/nginx NodePort 10.96.65.155 <none> 80:30201/TCP 30m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 2/2 2 2 30m
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-658c56bc8 2 2 2 30m
部署后会生成terraform.tfstate本地状态记录文件。
- terraform destroy
如果需要清理数据，则可以使用destroy命令清理。
4. 总结
本文以k8s平台为例展示了terraform的基本使用步骤，相比于kubectl和helm的k8s部署工具，terraform无根本区别。
-
terraform的优势在于以IaC（基础设施即代码）和GitOps的思想把将基础设施相关的运维部署操作以
声明式的方式记录在代码中，通过Git去管理期望的最终状态和版本迭代。 -
同时terraform可以对接绝大部分的基础设施，例如MySQL，Redis等，可以对接各个不同的部署平台和系统，例如阿里云，aws等，也可以针对公司内部的平台，单独写内部平台对接的provider，从而实现一套工具管理所有的基础设施。
参考：
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