Studio Log Format

June 29, 2018 · View on GitHub

🎩 Transform streams to format Studio Log streams

This module also works in the browser using a naive stream shim for small Browserify bundles.

Usage

const FancyFormat = require('@studio/log-format/fancy');

require('@studio/log')
  .pipe(new FancyFormat())
  .pipe(process.stdout);

Install

❯ npm i @studio/log-format

API

Transform Streams

  • @studio/log-format/basic: Basic formatting with ISO dates and no colors.
  • @studio/log-format/fancy: Colored output with localized dates. This is the default formatter when using the emojilog CLI.

Some advanced formatting is applied by naming conventions on top level properties of the data object.

  • ts or prefix ts_ formats a timestamp.
  • ms or prefix ms_ formats a millisecond value.
  • bytes or prefix bytes_ formats a byte value.

These options can be passed to the bundled format transforms:

  • ts: false hide timestamps
  • topic: false hide topics
  • ns: false hide namespaces
  • data: false hide data
  • stack: style with these stack styles:
    • false: hide the error entirely
    • message only show the error message
    • peek show the message and the first line of the trace (default)
    • full show the message and the full trace

The stack option is also used to format the "cause", if present.

Writable Streams

  • @studio/log-format/console: Console logger, making use of the console.log default formatting. This format has no options.

Custom Format Transforms

You can also write your own format transforms by implementing a node transform streams in writableObjectMode. Here is an example transform implementation, similar to the ndjson transform for Studio Log:

const { Transform } = require('stream');

const ndjson = new Transform({
  writableObjectMode: true,

  transform(entry, enc, callback) {
    const str = JSON.stringify(entry);
    callback(null, `${str}\n`);
  }
});

License

MIT

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