エピローグ — API戦略とDeveloper Experience

# curl一発でAPIを試せる
curl -H "Authorization: Bearer YOUR_TOKEN" \
     https://api.livly.jp/v1/properties | jq .

# Rubyクライアント（SDK）が公開されている
require 'livly'
 
Livly.api_key = 'your_api_key'
 
properties = Livly::Property.list(
  prefecture: '東京都',
  per_page: 5
)
 
properties.each do |p|
  puts "#{p.name}: #{p.price}円/月"
end

// 悪いエラーメッセージ
{
  "error": "invalid_request"
}
 
// 良いエラーメッセージ
{
  "type": "https://api.livly.jp/errors/validation_failed",
  "title": "Validation Failed",
  "status": 422,
  "detail": "入力内容に誤りがあります",
  "errors": [
    {
      "field": "price",
      "message": "は0以上の値にしてください",
      "code": "greater_than_or_equal_to",
      "docs": "https://docs.livly.jp/api/v1/properties#price"
    }
  ]
}

# 本番とサンドボックスを切り替えるだけ
Livly.configure do |config|
  config.api_key = ENV['LIVLY_API_KEY']
  config.environment = :sandbox  # または :production
end

# lib/livly.rb
module Livly
  class << self
    attr_accessor :api_key, :environment, :timeout
 
    def configure
      yield self
    end
 
    def base_url
      case environment
      when :sandbox    then 'https://api.sandbox.livly.jp/v1'
      when :production then 'https://api.livly.jp/v1'
      else                  'https://api.livly.jp/v1'
      end
    end
  end
 
  # デフォルト設定
  self.environment = :production
  self.timeout = 30
end

# lib/livly/property.rb
module Livly
  class Property
    attr_reader :id, :name, :price, :area, :location, :created_at
 
    def self.list(params = {})
      response = Client.get('/properties', params)
      response['data'].map { |d| new(d['attributes'].merge(id: d['id'])) }
    end
 
    def self.find(id)
      response = Client.get("/properties/#{id}")
      new(response['data']['attributes'].merge(id: response['data']['id']))
    end
 
    def self.create(attributes)
      response = Client.post('/properties', { property: attributes })
      new(response['data']['attributes'].merge(id: response['data']['id']))
    end
 
    def initialize(attributes = {})
      @id = attributes[:id] || attributes['id']
      @name = attributes[:name] || attributes['name']
      @price = attributes[:price] || attributes['price']
      @area = attributes[:area] || attributes['area']
      @location = attributes[:location] || attributes['location']
    end
  end
end

# 廃止予定フィールドの処理
module Api
  module V1
    class PropertiesController < Api::V1::BaseController
      def show
        @property = Property.find(params[:id])
        response = PropertySerializer.new(@property).serializable_hash
 
        # 廃止予定フィールドを残しつつ警告ヘッダーを付ける
        response[:data][:attributes][:address] = @property.full_address  # 旧フィールド
        response.headers['Warning'] = '299 api.livly.jp "address field is deprecated, use location instead"'
 
        render json: response
      end
    end
  end
end

# config/initializers/datadog.rb
Datadog.configure do |c|
  c.service = 'livly-api'
  c.env = Rails.env
 
  c.tracing.instrument :rails
  c.tracing.instrument :active_record
  c.tracing.instrument :http
 
  c.runtime_metrics.enabled = true
end

# SLI（Service Level Indicator）の定義
# 以下を継続的に計測する
 
# 1. 可用性（Availability）
# 目標: 99.9%（月間ダウンタイム43分以内）
# 計測: successful_requests / total_requests
 
# 2. レイテンシ（Latency）
# 目標: p99 < 500ms, p50 < 100ms
# 計測: CloudWatch / Datadog でパーセンタイル計測
 
# 3. エラー率（Error Rate）
# 目標: 5xxエラー率 < 0.1%
# 計測: 5xx_count / total_count
 
# 4. スループット（Throughput）
# 計測: 1分あたりのリクエスト数（RPS）

# webhookでリアルタイム通知
class WebhookDeliveryService
  def self.deliver(organization, event_type, payload)
    webhooks = organization.webhooks.active.where(
      'event_types @> ARRAY[?]::varchar[]', [event_type]
    )
 
    webhooks.each do |webhook|
      WebhookDeliveryJob.perform_later(webhook.id, event_type, payload)
    end
  end
end
 
class WebhookDeliveryJob < ApplicationJob
  retry_on StandardError, wait: :polynomially_longer, attempts: 5
 
  def perform(webhook_id, event_type, payload)
    webhook = Webhook.find(webhook_id)
    signature = compute_signature(webhook.secret, payload)
 
    response = HTTParty.post(webhook.url,
      body: payload.to_json,
      headers: {
        'Content-Type' => 'application/json',
        'X-Livly-Signature' => "sha256=#{signature}",
        'X-Livly-Event' => event_type,
        'X-Livly-Delivery' => SecureRandom.uuid
      },
      timeout: 10
    )
 
    webhook.deliveries.create!(
      event_type: event_type,
      response_status: response.code,
      success: response.success?
    )
  end
 
  private
 
  def compute_signature(secret, payload)
    OpenSSL::HMAC.hexdigest('SHA256', secret, payload.to_json)
  end
end