CLIとjqによるクラウドリソースのスクリプト操作

冪等なクラウドスクリプトが重要な理由

クラウドCLIのインストールと検証

#!/usr/bin/env bash
set -euo pipefail

check_or_install() {
  local cmd="$1"
  local install_cmd="$2"
  if ! command -v "$cmd" &>/dev/null; then
    echo "[INFO] $cmd not found — installing..."
    eval "$install_cmd"
  else
    echo "[OK]   $cmd $("$cmd" --version 2>&1 | head -1)"
  fi
}

# AWS CLI v2
check_or_install aws \
  'curl -fsSL https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip -o /tmp/awscliv2.zip && unzip -q /tmp/awscliv2.zip -d /tmp && sudo /tmp/aws/install'

# jq
check_or_install jq \
  'sudo apt-get install -y jq 2>/dev/null || sudo yum install -y jq'

# gcloud (optional)
check_or_install gcloud \
  'echo "Install gcloud SDK manually from https://cloud.google.com/sdk"'

echo "All prerequisites satisfied."

jqによる既存リソースの照会

#!/usr/bin/env bash
set -euo pipefail

BUCKET="my-devops-artifacts-$(date +%Y%m)"

echo "Fetching existing S3 buckets..."
EXISTING=$(aws s3api list-buckets --output json)

# Extract names as newline-separated list
echo "$EXISTING" | jq -r '.Buckets[].Name'

# Check if target bucket exists
if echo "$EXISTING" | jq -e --arg b "$BUCKET" '.Buckets[] | select(.Name == $b)' > /dev/null 2>&1; then
  echo "[EXISTS] Bucket $BUCKET already present — skipping creation."
else
  echo "[MISSING] Bucket $BUCKET not found — will create."
fi

冪等なS3バケットの作成

#!/usr/bin/env bash
set -euo pipefail

REGION="eu-west-1"
BUCKET="my-devops-artifacts-$(date +%Y%m)"

ensure_bucket() {
  local bucket="$1"
  local region="$2"

  local existing
  existing=$(aws s3api list-buckets --query 'Buckets[].Name' --output json)

  if echo "$existing" | jq -e --arg b "$bucket" 'index($b) != null' > /dev/null 2>&1; then
    echo "[SKIP] Bucket $bucket already exists."
    return 0
  fi

  echo "[CREATE] Creating bucket $bucket in $region..."
  aws s3api create-bucket \
    --bucket "$bucket" \
    --region "$region" \
    --create-bucket-configuration LocationConstraint="$region"

  # Enable versioning immediately after creation
  aws s3api put-bucket-versioning \
    --bucket "$bucket" \
    --versioning-configuration Status=Enabled

  echo "[DONE] Bucket $bucket created with versioning enabled."
}

ensure_bucket "$BUCKET" "$REGION"

ネストされたJSONの解析：EC2インスタンスの状態

#!/usr/bin/env bash
set -euo pipefail

INSTANCE_NAME="web-server-prod"

RESULT=$(aws ec2 describe-instances \
  --filters \
    "Name=tag:Name,Values=${INSTANCE_NAME}" \
    "Name=instance-state-name,Values=running" \
  --output json)

# Extract instance ID and private IP using jq
INSTANCE_ID=$(echo "$RESULT" | jq -r \
  '.Reservations[].Instances[] | .InstanceId')

PRIVATE_IP=$(echo "$RESULT" | jq -r \
  '.Reservations[].Instances[] | .PrivateIpAddress')

if [[ -z "$INSTANCE_ID" ]]; then
  echo "[WARN] No running instance named '$INSTANCE_NAME' found."
  exit 1
fi

echo "Instance ID : $INSTANCE_ID"
echo "Private IP  : $PRIVATE_IP"

冪等なIAMロールのプロビジョニング

#!/usr/bin/env bash
set -euo pipefail

ROLE_NAME="DevOpsDeployRole"
POLICY_ARN="arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess"

TRUST_POLICY='{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Principal": { "Service": "ec2.amazonaws.com" },
    "Action": "sts:AssumeRole"
  }]
}'

# Attempt creation; ignore EntityAlreadyExists
CREATE_OUTPUT=$(aws iam create-role \
  --role-name "$ROLE_NAME" \
  --assume-role-policy-document "$TRUST_POLICY" \
  --output json 2>&1) || {
  if echo "$CREATE_OUTPUT" | grep -q 'EntityAlreadyExists'; then
    echo "[SKIP] Role $ROLE_NAME already exists."
  else
    echo "[ERROR] Unexpected error: $CREATE_OUTPUT" >&2
    exit 1
  fi
}

# Attach policy (attach-role-policy is idempotent by default)
aws iam attach-role-policy \
  --role-name "$ROLE_NAME" \
  --policy-arn "$POLICY_ARN"

echo "[OK] Role $ROLE_NAME ready with policy $POLICY_ARN."

jq応用：変換、map、toentries

#!/usr/bin/env bash
set -euo pipefail

OUTPUT_FILE="/tmp/ec2_inventory.tsv"

aws ec2 describe-instances \
  --filters "Name=instance-state-name,Values=running" \
  --output json \
| jq -r '
  ["InstanceId", "Name", "PrivateIp", "Type", "AZ"],
  [
    .Reservations[].Instances[] | [
      .InstanceId,
      (.Tags // [] | map(select(.Key == "Name")) | .[0].Value // "(none)"),
      (.PrivateIpAddress // "N/A"),
      .InstanceType,
      .Placement.AvailabilityZone
    ]
  ][]
| @tsv' > "$OUTPUT_FILE"

echo "Inventory written to $OUTPUT_FILE:"
column -t "$OUTPUT_FILE"

非同期処理の待機：jqによるポーリング

#!/usr/bin/env bash
set -euo pipefail

INSTANCE_ID="i-0abcdef1234567890"
MAX_WAIT=300   # seconds
INTERVAL=10
ELAPSED=0

echo "Waiting for instance $INSTANCE_ID to reach 'running' state..."

while true; do
  STATE=$(aws ec2 describe-instances \
    --instance-ids "$INSTANCE_ID" \
    --output json \
  | jq -r '.Reservations[0].Instances[0].State.Name')

  echo "  [$(date +%T)] state = $STATE"

  [[ "$STATE" == "running" ]] && break

  if [[ "$STATE" == "terminated" || "$STATE" == "shutting-down" ]]; then
    echo "[FATAL] Instance entered terminal state: $STATE" >&2
    exit 1
  fi

  if (( ELAPSED >= MAX_WAIT )); then
    echo "[TIMEOUT] Instance did not reach 'running' after ${MAX_WAIT}s." >&2
    exit 1
  fi

  sleep "$INTERVAL"
  (( ELAPSED += INTERVAL ))
done

echo "[OK] Instance $INSTANCE_ID is running."

マルチクラウドパターン：GCPとAzureでの同等の方法

#!/usr/bin/env bash
set -euo pipefail

# --- Azure: idempotent resource group ---
RG="devops-rg"
LOCATION="westeurope"

if [[ $(az group exists --name "$RG") == "true" ]]; then
  echo "[SKIP] Azure resource group $RG already exists."
else
  echo "[CREATE] Creating Azure resource group $RG..."
  az group create --name "$RG" --location "$LOCATION" --output json \
    | jq '{name: .name, location: .location, provisioningState: .properties.provisioningState}'
fi

# --- GCP: idempotent GCS bucket ---
GCS_BUCKET="gs://devops-artifacts-prod"
PROJECT="my-gcp-project"

if gcloud storage buckets describe "$GCS_BUCKET" \
     --project="$PROJECT" --format='value(name)' &>/dev/null; then
  echo "[SKIP] GCS bucket $GCS_BUCKET already exists."
else
  echo "[CREATE] Creating GCS bucket $GCS_BUCKET..."
  gcloud storage buckets create "$GCS_BUCKET" \
    --project="$PROJECT" \
    --location=EU \
    --uniform-bucket-level-access
fi

ティアダウン：安全なリソース削除

#!/usr/bin/env bash
set -euo pipefail

DRY_RUN="${1:-}"

echo "Finding staging EC2 instances..."

INSTANCE_IDS=$(aws ec2 describe-instances \
  --filters \
    "Name=tag:Env,Values=staging" \
    "Name=instance-state-name,Values=running,stopped" \
  --output json \
| jq -r '[.Reservations[].Instances[].InstanceId] | @sh')

if [[ -z "$INSTANCE_IDS" ]]; then
  echo "[INFO] No staging instances found. Nothing to do."
  exit 0
fi

echo "Instances to terminate: $INSTANCE_IDS"

if [[ "$DRY_RUN" == "--dry-run" ]]; then
  echo "[DRY-RUN] No changes made."
  exit 0
fi

read -rp "Terminate these instances? [yes/N]: " CONFIRM
[[ "$CONFIRM" != "yes" ]] && { echo "Aborted."; exit 0; }

# shellcheck disable=SC2086
aws ec2 terminate-instances --instance-ids $INSTANCE_IDS --output json \
| jq '.TerminatingInstances[] | {id: .InstanceId, state: .CurrentState.Name}'

echo "[DONE] Termination initiated."

エンドツーエンド：冪等なインフラストラクチャブートストラップスクリプト

#!/usr/bin/env bash
set -euo pipefail

STATE_FILE="/tmp/infra_state.json"
REGION="eu-west-1"
BUCKET="devops-bootstrap-$(date +%Y%m)"
ROLE="BootstrapRole"

log() { echo "[$(date -u +%T)] [$1] ${*:2}"; }
trap 'log ERROR "Script failed at line $LINENO"' ERR

# Initialize state
[[ -f "$STATE_FILE" ]] || echo '{}' > "$STATE_FILE"

# --- Step 1: S3 bucket ---
EXISTING_BUCKETS=$(aws s3api list-buckets --query 'Buckets[].Name' --output json)
if echo "$EXISTING_BUCKETS" | jq -e --arg b "$BUCKET" 'index($b) != null' > /dev/null; then
  log INFO "Bucket $BUCKET exists — skipping."
else
  aws s3api create-bucket --bucket "$BUCKET" --region "$REGION" \
    --create-bucket-configuration LocationConstraint="$REGION" > /dev/null
  log INFO "Bucket $BUCKET created."
fi

# Update state file
jq --arg b "$BUCKET" '.bucket = $b' "$STATE_FILE" > /tmp/_state_tmp && mv /tmp/_state_tmp "$STATE_FILE"

# --- Step 2: IAM role ---
if aws iam get-role --role-name "$ROLE" &>/dev/null; then
  log INFO "Role $ROLE exists — skipping."
else
  aws iam create-role --role-name "$ROLE" \
    --assume-role-policy-document '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"ec2.amazonaws.com"},"Action":"sts:AssumeRole"}]}' \
    --output json | jq '{RoleName: .Role.RoleName, Arn: .Role.Arn}'
  log INFO "Role $ROLE created."
fi

jq --arg r "$ROLE" '.role = $r' "$STATE_FILE" > /tmp/_state_tmp && mv /tmp/_state_tmp "$STATE_FILE"

log INFO "Bootstrap complete. State: $(cat "$STATE_FILE" | jq -c .)"

理解度チェック：jqによる冪等性ガード

振り返り：CLIとjqによるクラウドリソースのスクリプティング