Merge pull request #49 from sh1un/feature/How-to-use-Terraform-Import…

…-to-import-existing-resources-into-IaC feat: add a new blog post, how to use `terraform import`
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diff --git a/...ntent/blog/How-to-use-Terraform-Import-to-import-existing-resources-into-IaC.md b/...ntent/blog/How-to-use-Terraform-Import-to-import-existing-resources-into-IaC.md
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+---
+title: '要導入 IaC？用 Terraform Import 導入現有資源'
+date: 2024-06-06T10:50:53+08:00
+draft: false
+description: "過去我們可能習慣直接在 AWS Console 上建立資源，但是現在想導入 IaC，把原本建立好的資源改成用 Terraform 管理。這篇文章會教你如何使用 Terraform Import 功能，將現有的資源導入到 Terraform 的 State 中"
+tags: ["Terraform", "IaC", "AWS", "Version Control", "Terraform Import", "DevOps", "Cloud Infrastructure", "Technical Tutorial"]
+categories: ["IaC", "Terraform", "AWS", "DevOps"]
+keywords:
+- Terraform
+- Terraform Import
+- Infrastructure as Code
+- IaC
+- AWS
+- AWS EC2
+- DevOps
+- Cloud Management
+- Cloud Infrastructure
+- Terraform Tutorial
+- AWS Tutorial
+- Import AWS Resources
+- Terraform State
+- Cloud Automation
+- AWS Console
+- Infrastructure Management
+---
+## Import
+
+### 簡介
+
+Terraform Import 是 Terraform 中的一個功能，允許你將現有的基礎設施資源導入到 Terraform 的狀態文件中。這樣，你可以將已有的基礎設施與 Terraform 的配置文件同步，並開始使用 Terraform 來管理這些資源
+
+### 什麼時候需要用到 `terraform import`？
+
+> terraform import 並不是一個自動偵測 AWS 資源上的東西，然後自動幫忙寫程式碼的工具
+如果你以前沒有使用任何 IaC 的工具，都是直接在 AWS Console 上管理和創建資源，但現在想要導入 IaC，然後把那些「現有資源」導入到 Terraform 來管理，那你就會需要用到 `terraform import`
+
+`terraform import` 的主要目的是將已經存在的基礎設施資源導入到 Terraform 的狀態文件中，這樣你就可以用 Terraform 來管理這些資源。例如，如果你有一個已經存在的 AWS EC2 實例，而你現在想開始用 Terraform 來管理它，你需要導入這個實例以便 Terraform 知道它的存在和當前狀態
+
+### Synopsis
+
+```bash
+$ terraform import [options] ADDRESS ID
+```
+
+- `ADDRESS` 是 Terraform 配置中資源的地址。例如，`aws_instance.my_instance`
+- `ID` 是資源的唯一標識符，這個值根據不同的資源類型會有所不同。例如，對於 AWS EC2 實例，這個 ID 是實例的 ID（例如 `i-1234567890abcdef0`）
+
+### Example
+
+```bash
+$ terraform import aws_instance.my_instance i-1234567890abcdef0
+
+data.aws_region.current: Reading...
+data.aws_availability_zones.available: Reading...
+data.aws_ami.ubuntu: Reading...
+aws_instance.aws_linux: Import prepared!
+  Prepared aws_instance for import
+aws_instance.aws_linux: Refreshing state... [id=i-00066e5627229c90e]
+data.aws_region.current: Read complete after 0s [id=us-east-1]
+data.aws_availability_zones.available: Read complete after 1s [id=us-east-1]
+data.aws_ami.ubuntu: Read complete after 1s [id=ami-0f81732f07ce19b1c]
+
+Import successful!
+
+The resources that were imported are shown above. These resources are now in
+your Terraform state and will henceforth be managed by Terraform.
+```
+
+### Hands-on
+
+到 AWS Console 創建資源
+
+我這邊創建了一台 EC2 Instance
+
+![01-created_instance](https://github.com/sh1un/sh1un.github.io/assets/85695943/fc903bf3-d29f-4db5-ade8-8ebac02c1ca6)
+
+接著在 [main.tf](http://main.tf) 加入以下程式碼:
+
+```bash
+resource "aws_instance" "aws_linux" {
+
+}
+```
+
+打開 Terminal 使用 `terraform import` 來 import 現有的資源
+
+```bash
+$ terraform import aws_instance.aws_linux i-00066e5627229c90e
+
+data.aws_region.current: Reading...
+data.aws_availability_zones.available: Reading...
+data.aws_ami.ubuntu: Reading...
+aws_instance.aws_linux: Import prepared!
+  Prepared aws_instance for import
+aws_instance.aws_linux: Refreshing state... [id=i-00066e5627229c90e]
+data.aws_region.current: Read complete after 0s [id=us-east-1]
+data.aws_availability_zones.available: Read complete after 1s [id=us-east-1]
+data.aws_ami.ubuntu: Read complete after 1s [id=ami-0f81732f07ce19b1c]
+
+Import successful!
+
+The resources that were imported are shown above. These resources are now in
+your Terraform state and will henceforth be managed by Terraform.
+```
+
+用 `terraform state list` 查看一下現在的 state，會看到我們的 `aws_instance.aws_linux`
+
+![02-terraform_state_list_output](https://github.com/sh1un/sh1un.github.io/assets/85695943/3dbafed0-c5ac-4230-9015-c8cfe7bb7d17)
+
+輸入看看 `terraform plan` :
+
+```bash
+$ terrafomr plan
+
+╷
+│ Error: Missing required argument
+│
+│   with aws_instance.aws_linux,
+│   on main.tf line 263, in resource "aws_instance" "aws_linux":
+│  263: resource "aws_instance" "aws_linux" {
+│
+│ "launch_template": one of `ami,instance_type,launch_template` must be specified
+╵
+╷
+│ Error: Missing required argument
+│
+│   with aws_instance.aws_linux,
+│   on main.tf line 263, in resource "aws_instance" "aws_linux":
+│  263: resource "aws_instance" "aws_linux" {
+│
+│ "ami": one of `ami,launch_template` must be specified
+╵
+╷
+│ Error: Missing required argument
+│
+│   with aws_instance.aws_linux,
+│   on main.tf line 263, in resource "aws_instance" "aws_linux":
+│  263: resource "aws_instance" "aws_linux" {
+│
+│ "instance_type": one of `instance_type,launch_template` must be specified
+```
+
+出現 ERROR 很正常，畢竟就是看著我們的程式碼去執行該指令，而我們的 `resource "aws_instance" "aws_linux" {}` 裡面都沒配置任何參數當然會出錯，要解決可以用 `terraform state show` 來處理，把這個資源的詳細資訊配置到我們程式碼，因為我們已經知道他被寫入 state
+
+使用 `terraform state show` 來查看資源的詳細資訊:
+
+```bash
+$ terraform state show aws_instance.aws_linux
+
+# aws_instance.aws_linux:
+resource "aws_instance" "aws_linux" {
+    ami                                  = "ami-00beae93a2d981137"
+    arn                                  = "arn:aws:ec2:us-east-1:058264428816:instance/i-00066e5627229c90e"
+    associate_public_ip_address          = true
+    availability_zone                    = "us-east-1b"
+    cpu_core_count                       = 1
+    cpu_threads_per_core                 = 1
+    disable_api_stop                     = false
+    disable_api_termination              = false
+    ebs_optimized                        = false
+    get_password_data                    = false
+    hibernation                          = false
+    host_id                              = null
+# 略...
+```
+
+然後根據上面面 `terraform state show` 輸出的結果把程式碼改成如下:
+
+```bash
+# main.tf
+
+resource "aws_instance" "aws_linux" {
+
+  instance_type = "t2.micro"
+  ami           = "ami-00beae93a2d981137"
+
+}
+
+```
+
+接著再輸入 `terraform plan` 就不會報錯了，此時我們原先在 AWS Console 上手動建立了資源就被 Terraform 所管
+
+如果我們要刪掉那個資源也可以透過 terraform 來刪除，我們把原先那行註解掉:
+
+```bash
+# main.tf
+
+# resource "aws_instance" "aws_linux" {
+
+#   instance_type = "t2.micro"
+#   ami           = "ami-00beae93a2d981137"
+
+# }
+```
+
+接著我們再來執行 `terraform plan` :
+
+```bash
+$ terraform plan
+
+# 略...
+# aws_instance.aws_linux will be destroyed
+  # (because aws_instance.aws_linux is not in configuration)
+  - resource "aws_instance" "aws_linux" {
+      - ami                                  = "ami-00beae93a2d981137" -> null
+      - arn                                  = "arn:aws:ec2:us-east-1:058264428816:instance/i-00066e5627229c90e" -> null
+      - associate_public_ip_address          = true -> null
+      - availability_zone                    = "us-east-1b" -> null
+      - cpu_core_count                       = 1 -> null
+
+```
+
+### Resources
+
+- [Import | Terraform | HashiCorp Developer](https://developer.hashicorp.com/terraform/cli/import)
+- [Shiun's Learning Journal - 20240605](https://www.notion.so/20240605-a29a522dba9d4e8eb7a60fe899595908?pvs=21)
diff --git a/blog/public/archives/index.html b/blog/public/archives/index.html
@@ -253,8 +253,19 @@ <h1>
   </h1>
 </header>
 <div class="archive-year">
-  <h2 class="archive-year-header">2024<sup class="archive-count">&nbsp;&nbsp;10</sup>
+  <h2 class="archive-year-header">2024<sup class="archive-count">&nbsp;&nbsp;11</sup>
   </h2>
+  <div class="archive-month">
+    <h3 class="archive-month-header">June<sup class="archive-count">&nbsp;&nbsp;1</sup></h3>
+    <div class="archive-posts">
+      <div class="archive-entry">
+        <h3 class="archive-entry-title entry-hint-parent">要導入 IaC？用 Terraform Import 導入現有資源
+        </h3>
+        <div class="archive-meta"><span title='2024-06-06 10:50:53 +0800 CST'>June 6, 2024</span>&nbsp;·&nbsp;3 min</div>
+        <a class="entry-link" aria-label="post link to 要導入 IaC？用 Terraform Import 導入現有資源" href="https://shiun.me/blog/how-to-use-terraform-import-to-import-existing-resources-into-iac/"></a>
+      </div>
+    </div>
+  </div>
   <div class="archive-month">
     <h3 class="archive-month-header">May<sup class="archive-count">&nbsp;&nbsp;1</sup></h3>
     <div class="archive-posts">

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