April 2022
Beginner to intermediate
464 pages
6h 44m
Japanese
Content preview from 実用 Go言語 ―システム開発の現場で知っておきたいアドバイス
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12.4 構造化ログを出力する
AWSであればCloudWatch Logs、Google Cloundの場合はCloud Loggingというログ管理のサービスがあります。これらのサービスではログ表示のUIを提供しており、出力されたログをフィルタリングして検索したりできます。このようなサービスを利用するにあたって、利用しやすいログ形式が 構造化ロギング です。構造化ロギングはキーと値のペアを持つことができ、分析がしやすいログ形式です。どちらのサービスもJSON形式に対応しています。
構造化ログは標準出力に出力された内容をエージェントが収集し、これらのサービスに送信しています。このような場面で使えるGoライブラリとして有名なのが、rs/zerologと go.uber.org/zapです。本書では前者を取り上げます。「ライブラリがなくてもできる」と紹介しましたが、ログを整形して出力する、同一の設定で何度も出力する、といった場合には何らかのライブラリを使った方が便利です。 zerologは速度を売りにした構造化ログを出力するためのライブラリで、デフォルトでは標準出力などに出力します。このJSON作成時のパフォーマンスが高いライブラリです。標準のlogパッケージはお手軽ですが、構造化ログを出力するには手間がかかります。
12.4.1 zerologの基本とログレベル
zerologを利用するには次のようにインポートします。rs/zerolog/logは簡単に扱えるようにラップされたAPIで、rs/zerologの方が細かい設定ができる詳細なAPIになっています。
import (
"github.com/rs/zerolog"
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.