@jackdbd/tags-logger

A logger inspired by how logging is implemented in Hapi.js.

Table of Contents

• Features
• Installation
• Usage
  • structured logging
  • unstructured logging
• Configuration
  • Environment variables
  • Options
• API

Features

• tags to pinpoint the log statements you are actually interested in.
• optional validation of all log statements with Joi.
• easy switching bewteen structured/unstructured logging.

Installation

npm install @jackdbd/tags-logger
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Usage

structured logging

When you write this:

import makeLog from '@jackdbd/tags-logger'

const log = makeLog()

log({
  message: 'something not very important about foo and bar',
  tags: ['debug', 'foo', 'bar']
})

log({
  message: 'something of critical importance about baz',
  tags: ['critical', 'baz']
})
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You get this:

{
  "severity": "DEBUG",
  "message": "something not very important about foo and bar",
  "tags": ["bar", "foo"],
  "tag": {"bar": true, "foo": true}
}

{
  "severity": "CRITICAL",
  "message": "something of critical importance about baz",
  "tags": ["baz"],
  "tag": {"baz": true}
}
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unstructured logging

When you write this:

import makeLog from '@jackdbd/tags-logger'

const log = makeLog({
  namespace: 'my-app/my-module'
})

// same log statements as above
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You get this (but with colors):

my-app/my-module [🔍 bar,foo] something not very important about foo and bar +0ms

my-app/my-module [🔥 baz] something of critical importance about baz +0ms
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Don't like emojis? Then write this:

import makeLog from '@jackdbd/tags-logger'

const log = makeLog({
  namespace: 'my-app/my-module',
  should_use_emoji_for_severity: false // <--
})

// same log statements as above
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And get this (but with colors):

my-app/my-module [debug bar,foo] something not very important about foo and bar +0ms

my-app/my-module [critical baz] something of critical importance about baz +0ms
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Configuration

Environment variables

Environment variable	Explanation
DEBUG	You must set this environment variable if you want to use unstructured logging and see some output. This library delegates unstructured logging to debug.

Options

Option	Default	Explanation
namespace	undefined	The namespace for unstructured logging. This option has no effect when using structured logging.
should_use_emoji_for_severity	true	Whether to use an emoji for the severity level, when using unstructured logging. This option has no effect when using structured logging.
should_validate_log_statements	false when process.env.NODE_ENV === 'production'. Otherwise true	Whether each log statement should be validated against a Joi schema.

API

API docs generated with TypeDoc