@tlscipher/holt

A highly configurable logger middleware for ElysiaJS.

Named after Raymond Holt from Brooklyn Nine-Nine

Installation

bun add @tlscipher/holt

Usage

import { HoltLogger } from "@tlscipher/holt";
import { Elysia } from "elysia";

new Elysia()
  .use(new HoltLogger().getLogger())
  .get("/", () => {})
  .listen(3000);

Configuration

HoltLogger

The constructor for HoltLogger function accepts an optional parameter of type HoltConfig.

interface HoltConfig {
  format: string;
  colorful: boolean;
}

• format (Default: ":date | :method :path - :status (:request-duration ms)")

  • The format parameter allows you to customize the log output that is written to the console using tokens.

• colorful (Default: true)

  • The colorful parameter allows to specifiy a boolean value of wether or not you would like the logger output to be color-coded based on the HTTP response status code.

Possible Tokens for Format

• :date The time at which the response was sent.
  • Example output: 2023-09-16T21:15:04.516Z
• :method The HTTP method that was used for the inbound request.
  • Example output: GET
• :path The path of the inbound HTTP request
  • Example output: /health
• :request-duration The difference in milliseconds from the time the request was received, to the time the response was sent
  • Example output: 4.28

Adding Headers to the Format

This package allows you to log any of the available incoming headers.

Format for header tokens:

• :header[<header-key-here>]

Examples:

• :header[user-agent]
  • Example output: PostmanRuntime/7.33.0
• :header[accept]
  • Example output: application/json
• :header[authorization]
  • Example output: Bearer auth_xxxxxx...

Custom Tokens

You can now add custom tokens to your logger using the HoltLogger.token function. The function accepts the following parameters:

• token (required string)
  • The string to be tokenized and used and the replacer in the format
• extractFn (required function)
  • The function will be given access to select properties of ELysia's context and must return the string value to replace the token in the format.

Example Custom Token Usage

import { HoltLogger } from "@tlscipher/holt";
import { Elysia } from "elysia";

new Elysia()
  .use(
    new HoltLogger({
      format: ":method :path | :is-admin",
    })
      .token("is-admin", ({ headers }) => {
        return headers["x-admin-api-key"] === "admin-api-key-here"
          ? "Admin Request"
          : "User Request";
      })
      .getLogger()
  )
  .get("/", () => {})
  .listen(3000);