docs: add Terraform certification notes and tasks

terraform/task-37.md

@@ -0,0 +1,104 @@
+# Assignment
+
+The Nautilus DevOps team is strategizing the migration of a portion of their infrastructure to the AWS cloud. As part of this phased migration approach, they need to allocate an Elastic IP address to support external access for specific workloads.
+
+For this task, create an AWS Elastic IP using Terraform with the following requirement:
+
+The Elastic IP name xfusion-eip should be stored in a variable named KKE_eip. The Terraform working directory is /home/bob/terraform.
+Note:
+
+The configuration values should be stored in a variables.tf file.
+
+The Terraform script should be structured with a main.tf file referencing variables.tf.
+
+Right-click under the EXPLORER section in VS Code and select Open in Integrated Terminal to launch the terminal.
+
+# Solution
+
+# Elastic IP with Variables — `xfusion-eip` (`KKE_eip`)
+
+Two-file structure: `variables.tf` holds the config, `main.tf` references it. The
+Elastic IP name must be stored in a variable named exactly `KKE_eip`.
+
+## `variables.tf`
+
+```hcl
+variable "KKE_eip" {
+  description = "Name of the Elastic IP"
+  type        = string
+  default     = "xfusion-eip"
+}
+```
+
+## `main.tf`
+
+```hcl
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 6.0"
+    }
+  }
+}
+
+provider "aws" {
+  region = "us-east-1"
+}
+
+resource "aws_eip" "xfusion_eip" {
+  domain = "vpc"
+
+  tags = {
+    Name = var.KKE_eip
+  }
+}
+```
+
+## How to run
+
+```bash
+cd /home/bob/terraform
+terraform init
+terraform apply -auto-approve
+```
+
+## How it works
+
+### Splitting config from logic
+
+Terraform merges every `.tf` file in the directory into one configuration, so
+`variables.tf` and `main.tf` work as a single unit with no imports. `variables.tf`
+declares inputs; `main.tf` declares resources that consume them via `var.<name>`.
+
+### The variable
+
+- **`variable "KKE_eip"`** — holds the Elastic IP name, exactly as required. The
+  `default` of `xfusion-eip` lets `terraform apply` run without prompting.
+- **`type = string`** validates the input type at plan time.
+
+### The Elastic IP
+
+- **`domain = "vpc"`** — allocates the EIP for use in a VPC. This is the modern
+  argument; the old `vpc = true` was removed in AWS provider v5+, so on `~> 6.0` you
+  must use `domain`. Since the task only asks to *allocate* the address (no instance or
+  ENI association), no `instance` or `network_interface` argument is set.
+- **`tags = { Name = var.KKE_eip }`** — an Elastic IP has no native name field, so the
+  `Name` tag (resolved from the variable to `xfusion-eip`) is what the console and
+  graders read as its name.
+
+The `var.` prefix interpolates the declared variable's value. Because the variable has
+a default, `terraform apply` runs non-interactively.
+
+> Cost note: an unassociated Elastic IP incurs an hourly charge, but that's the
+> sandbox's concern — the task only requires the allocation to exist.
+
+## Verify
+
+```bash
+aws ec2 describe-addresses \
+  --filters Name=tag:Name,Values=xfusion-eip \
+  --query 'Addresses[0].{IP:PublicIp,AllocId:AllocationId,Name:Tags[?Key==`Name`]|[0].Value}'
+```
+
+Expected — a public IP, an allocation ID, and `Name: xfusion-eip`.