# Referensi Cepat Terraform

*Provider, resource, variabel, state, modul*

> Source: Terraform Documentation (developer.hashicorp.com/terraform) · MIT

## Dasar

### Alur Kerja Inti

```
terraform init      # install providers & modules
terraform plan      # preview changes
terraform apply     # apply changes
terraform destroy   # tear down all resources
```

### Perintah Esensial

| Command | Description |
|---------|-------------|
| `terraform init` | Inisialisasi direktori kerja, unduh provider |
| `terraform plan` | Tampilkan rencana eksekusi tanpa menerapkan |
| `terraform apply` | Terapkan perubahan ke infrastruktur |
| `terraform destroy` | Hancurkan semua resource yang dikelola |
| `terraform fmt` | Format file `.tf` ke gaya kanonik |
| `terraform validate` | Periksa sintaks konfigurasi |
| `terraform show` | Tampilkan state atau rencana saat ini |
| `terraform output` | Cetak nilai output |

## Provider

### Konfigurasi Provider

```
terraform {
  required_providers {
    aws = { source = "hashicorp/aws", version = "~> 5.0" }
  }
}
provider "aws" {
  region = "us-east-1"
}
```

### Catatan Provider

| Command | Description |
|---------|-------------|
| `source` | Alamat registry (`hashicorp/aws`, `hashicorp/google`) |
| `version` | Batasan versi (`~> 5.0`, `>= 3.0, < 4.0`) |
| `.terraform.lock.hcl` | Lock file — commit ke version control |
| `alias` | Gunakan beberapa konfigurasi untuk provider yang sama |

## Resource

### Blok Resource

```
resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"
  tags = { Name = "web-server" }
}
```

### Meta-Argumen Resource

| Command | Description |
|---------|-------------|
| `depends_on` | Dependensi eksplisit pada resource lain |
| `count` | Buat beberapa instance (`count = 3`) |
| `for_each` | Buat instance dari map atau set |
| `provider` | Pilih alias provider non-default |
| `lifecycle` | Sesuaikan perilaku buat/perbarui/hancurkan |

### Merujuk Resource

```
# type.name.attribute
aws_instance.web.id
aws_instance.web.public_ip
aws_vpc.main.cidr_block
```

## Variabel

### Deklarasi Variabel

```
variable "region" {
  type    = string
  default = "us-east-1"
}
variable "instance_count" {
  type        = number
  description = "Number of instances"
}
```

### Mengatur Nilai Variabel

| Command | Description |
|---------|-------------|
| `-var 'region=us-west-2'` | Flag CLI |
| `-var-file=prod.tfvars` | Muat dari file `.tfvars` |
| `terraform.tfvars` | Dimuat otomatis jika ada |
| `TF_VAR_region` | Variabel environment |
| `Interactive prompt` | Ditanyakan saat plan/apply jika tidak ada default |

### Tipe Variabel

| Command | Description |
|---------|-------------|
| `string` | `"us-east-1"` |
| `number` | `42` |
| `bool` | `true` / `false` |
| `list(string)` | `["a", "b"]` |
| `map(string)` | `{ key = "val" }` |
| `object({...})` | Tipe terstruktur dengan atribut bernama |

## Output

### Mendefinisikan Output

```
output "instance_ip" {
  value       = aws_instance.web.public_ip
  description = "Public IP of the web server"
}
output "db_password" {
  value     = random_password.db.result
  sensitive = true
}
```

### Perintah Output

| Command | Description |
|---------|-------------|
| `terraform output` | Cetak semua output |
| `terraform output instance_ip` | Cetak output tertentu |
| `terraform output -json` | Format JSON untuk scripting |
| `sensitive = true` | Sembunyikan nilai dari output CLI |
| `module.vpc.vpc_id` | Akses output modul anak |

## State

### Remote Backend

```
terraform {
  backend "s3" {
    bucket = "my-tf-state"
    key    = "prod/terraform.tfstate"
    region = "us-east-1"
  }
}
```

### Perintah State

| Command | Description |
|---------|-------------|
| `terraform state list` | Tampilkan semua resource dalam state |
| `terraform state show <addr>` | Tampilkan atribut resource |
| `terraform state mv <src> <dst>` | Ganti nama / pindahkan resource dalam state |
| `terraform state rm <addr>` | Hapus resource dari state (infra tetap ada) |
| `terraform state pull` | Unduh state remote ke stdout |
| `terraform import <addr> <id>` | Impor infra yang sudah ada ke state |

## Modul

### Menggunakan Modul

```
module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "~> 5.0"
  cidr    = "10.0.0.0/16"
}
```

### Sumber Modul

| Command | Description |
|---------|-------------|
| `"./modules/vpc"` | Path lokal |
| `"terraform-aws-modules/vpc/aws"` | Terraform Registry |
| `"github.com/org/repo//module"` | Repository GitHub |
| `"s3::https://bucket/module.zip"` | S3 bucket |

### Struktur Modul

```
modules/vpc/
  main.tf          # resources
  variables.tf     # input variables
  outputs.tf       # output values
```

## Data Source

### Membaca Resource yang Ada

```
data "aws_ami" "ubuntu" {
  most_recent = true
  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/*"]
  }
  owners = ["099720109477"]
}
```

### Data Source Umum

| Command | Description |
|---------|-------------|
| `data.aws_ami` | Cari AMI berdasarkan filter |
| `data.aws_vpc` | Cari VPC yang sudah ada |
| `data.aws_caller_identity` | ID akun AWS saat ini |
| `data.aws_region` | Region AWS saat ini |
| `data.terraform_remote_state` | Baca output dari file state lain |
| `data.external` | Jalankan program eksternal untuk data |

## Lifecycle

### Aturan Lifecycle

```
resource "aws_instance" "web" {
  lifecycle {
    create_before_destroy = true
    prevent_destroy       = true
    ignore_changes        = [tags]
  }
}
```

### Opsi Lifecycle

| Command | Description |
|---------|-------------|
| `create_before_destroy` | Buat pengganti sebelum menghancurkan yang lama |
| `prevent_destroy` | Error jika `terraform destroy` menarget ini |
| `ignore_changes` | Jangan deteksi drift pada atribut yang terdaftar |
| `replace_triggered_by` | Paksa penggantian ketika resource yang dirujuk berubah |
| `precondition` | Validasi asumsi sebelum apply |
| `postcondition` | Validasi hasil setelah apply |

## Pola Umum

### Loop & Kondisional

```
# for_each with a map
resource "aws_iam_user" "users" {
  for_each = toset(["alice", "bob"])
  name     = each.value
}
# conditional resource
count = var.create_db ? 1 : 0
```

### Fungsi Berguna

| Command | Description |
|---------|-------------|
| `file("key.pub")` | Baca isi file |
| `join(", ", list)` | Gabungkan list menjadi string |
| `lookup(map, key, default)` | Pencarian map dengan fallback |
| `length(list)` | Jumlah elemen |
| `toset(["a", "b"])` | Ubah list ke set (untuk for_each) |
| `try(expr, fallback)` | Kembalikan fallback jika expr error |
| `templatefile(path, vars)` | Render file template |