Harden generated config temp path creation

2026-04-14 20:18:16 +10:00
parent 5e49b6774b
commit 9ad21c5846
2 changed files with 121 additions and 0 deletions
@@ -0,0 +1,105 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'USAGE'
+Usage:
+  reconcile_from_plan.sh [--output-file <path>] [--] [terraform plan args...]
+
+Description:
+  Runs `terraform plan` with `-generate-config-out` and writes the generated
+  configuration into a tracked Terraform file (default:
+  `zz_generated_from_plan.auto.tf`).
+
+  This is designed for import-first workflows where `import { ... }` blocks are
+  present and Terraform can generate missing resource arguments from live
+  infrastructure.
+
+Options:
+  --output-file <path>  Destination .tf/.auto.tf file to receive generated
+                        configuration. Default: zz_generated_from_plan.auto.tf
+  -h, --help            Show this help text.
+
+Examples:
+  ./reconcile_from_plan.sh
+  ./reconcile_from_plan.sh --output-file generated_imports.auto.tf -- -var-file=terraform.tfvars
+USAGE
+}
+
+output_file="zz_generated_from_plan.auto.tf"
+plan_args=()
+
+while (($# > 0)); do
+  case "$1" in
+    --output-file)
+      if (($# < 2)); then
+        echo "error: --output-file requires a value" >&2
+        exit 1
+      fi
+      output_file="$2"
+      shift 2
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    --)
+      shift
+      plan_args=("$@")
+      break
+      ;;
+    *)
+      plan_args+=("$1")
+      shift
+      ;;
+  esac
+done
+
+if ! command -v terraform >/dev/null 2>&1; then
+  echo "error: terraform is not installed or not in PATH" >&2
+  exit 1
+fi
+
+if [[ ! -f "main.tf" ]] && ! compgen -G "*.tf" >/dev/null; then
+  echo "error: no Terraform configuration (*.tf) found in $(pwd)" >&2
+  echo "run this script from a Terraform module directory" >&2
+  exit 1
+fi
+
+generated_tmp_dir="$(mktemp -d -t terraform-generated-XXXXXX)"
+generated_tmp="$generated_tmp_dir/generated.tf"
+# terraform plan -generate-config-out requires a path that does not already exist
+trap 'rm -rf "$generated_tmp_dir"' EXIT
+
+echo "Running: terraform plan -generate-config-out=$generated_tmp ${plan_args[*]-}"
+set +e
+terraform plan -generate-config-out="$generated_tmp" "${plan_args[@]}"
+plan_exit=$?
+set -e
+
+if [[ $plan_exit -ne 0 && $plan_exit -ne 2 ]]; then
+  echo "error: terraform plan failed with exit code $plan_exit" >&2
+  exit "$plan_exit"
+fi
+
+if [[ ! -s "$generated_tmp" ]]; then
+  echo "No generated configuration was produced."
+  echo "Tip: ensure you have import blocks and resources eligible for config generation."
+  exit 0
+fi
+
+cat > "$output_file" <<EOF2
+# -----------------------------------------------------------------------------
+# AUTO-GENERATED BY reconcile_from_plan.sh
+# Generated: $(date -u +"%Y-%m-%dT%H:%M:%SZ")
+# Source: terraform plan -generate-config-out
+# Review carefully before apply.
+# -----------------------------------------------------------------------------
+
+EOF2
+cat "$generated_tmp" >> "$output_file"
+
+terraform fmt "$output_file" >/dev/null
+
+echo "Generated configuration written to: $output_file"
+echo "Next step: review this file and run terraform plan again to confirm intent."