docs: add Terraform certification notes and tasks

terraform/task-18.md

@@ -0,0 +1,111 @@
+# Assignment
+
+The Nautilus DevOps team needs to create an AWS Kinesis data stream for real-time data processing. This stream will be used to ingest and process large volumes of streaming data, which will then be consumed by various applications for analytics and real-time decision-making.
+
+The stream should be named xfusion-stream.
+
+Use Terraform to create this Kinesis stream.
+
+The Terraform working directory is /home/bob/terraform. Create the main.tf file (do not create a different .tf file) to accomplish this task.
+
+Note:
+
+Right-click under the EXPLORER section in VS Code and select Open in Integrated Terminal to launch the terminal.
+Before submitting the task, ensure that terraform plan returns No changes. Your infrastructure matches the configuration.
+
+# Solution
+
+# Kinesis Data Stream — `xfusion-stream`
+
+Terraform solution to create a provisioned Kinesis data stream with a single shard,
+configured so `terraform plan` reports no drift after apply.
+
+## `main.tf`
+
+```hcl
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 6.0"
+    }
+  }
+}
+
+provider "aws" {
+  region = "us-east-1"
+}
+
+resource "aws_kinesis_stream" "xfusion_stream" {
+  name             = "xfusion-stream"
+  shard_count      = 1
+  retention_period = 24
+
+  stream_mode_details {
+    stream_mode = "PROVISIONED"
+  }
+}
+```
+
+## How to run
+
+```bash
+cd /home/bob/terraform
+terraform init
+terraform apply -auto-approve
+
+# Idempotency check required by the task:
+terraform plan
+# -> "No changes. Your infrastructure matches the configuration."
+```
+
+## How it works
+
+### `aws_kinesis_stream`
+
+- **`name = "xfusion-stream"`** — the stream name, exactly as required.
+
+- **`stream_mode_details { stream_mode = "PROVISIONED" }`** — Kinesis has two
+  capacity modes: `PROVISIONED` (you manage shards) and `ON_DEMAND` (AWS
+  auto-scales). This is set to `PROVISIONED` explicitly. The two modes are mutually
+  exclusive with `shard_count`: `PROVISIONED` **requires** `shard_count`, while
+  `ON_DEMAND` **forbids** it. Getting this pairing wrong is the usual cause of a
+  perpetual non-empty plan or an apply error.
+
+- **`shard_count = 1`** — one shard. A shard is the base throughput unit (1 MB/s or
+  1000 records/s in, 2 MB/s out). One shard is plenty for a lab and is the
+  provisioned-capacity choice that pairs with `PROVISIONED` mode.
+
+- **`retention_period = 24`** — hours that records stay in the stream before aging
+  out. `24` is the AWS default and the minimum; setting it explicitly to the default
+  value keeps the resource stable and readable.
+
+### Why the plan comes back clean
+
+The task explicitly requires `terraform plan` to report **no changes** after apply.
+Two things guarantee that here:
+
+1. **Mode and shard count are consistent.** `PROVISIONED` + an explicit
+   `shard_count` is the stable, non-conflicting combination. Mixing `ON_DEMAND` with
+   a `shard_count`, or omitting the mode and letting it get inferred, is what
+   typically produces a drift diff on the next plan.
+
+2. **Every value set matches what AWS stores.** `retention_period = 24` equals the
+   service default, and no other arguments (encryption, shard-level metrics) are
+   toggled, so there's nothing for the provider to reconcile on refresh.
+
+### Sandbox note
+
+Constrained lab environments cap Kinesis at **PROVISIONED mode, 1 shard per stream,
+≤24h retention, and ≤2 streams per account**. This config sits inside every one of
+those limits, so it won't be silently reset or rejected.
+
+## Verify
+
+```bash
+aws kinesis describe-stream-summary --stream-name xfusion-stream \
+  --query 'StreamDescriptionSummary.{Name:StreamName,Status:StreamStatus,Mode:StreamModeDetails.StreamMode,Shards:OpenShardCount,Retention:RetentionPeriodHours}'
+```
+
+Expected — name `xfusion-stream`, `StreamStatus: ACTIVE` (a few seconds after
+create), `StreamMode: PROVISIONED`, `OpenShardCount: 1`, retention `24`.