diagnostics

What is diagnostics?

The 'diagnostics' npm package is designed to provide a comprehensive set of utilities for debugging and diagnostic purposes. It allows developers to output debug information, create diagnostic channels, and manage the verbosity of logging.

What are diagnostics's main functionalities?

Debugging

This feature allows developers to create namespaced debug logs. The code sample demonstrates how to create a debug instance for a specific namespace and log a message.

const debug = require('diagnostics')('my-namespace');
debug('doing some work');

Enabling Namespaces

This feature enables specific namespaces for logging. By setting the DEBUG environment variable, you can control which debug instances output logs. The code sample shows how to enable a namespace and log a message that will be output.

process.env.DEBUG = 'my-namespace';
const debug = require('diagnostics')('my-namespace');
debug('this will be logged');

Diagnostic Channels

This feature allows the creation of diagnostic channels for emitting and listening to custom events. The code sample creates a channel, listens for 'data' events, and emits a message.

const diagnostics = require('diagnostics');
const channel = diagnostics.channel('my-channel');
channel.on('data', (message) => {
  console.log('Received message:', message);
});
channel.write('Hello, diagnostics!');

Other packages similar to diagnostics

debug

The 'debug' package is similar to 'diagnostics' in that it allows developers to create small debugging utilities. It is widely used and focuses on simplicity and minimalism. Unlike 'diagnostics', it does not provide channels but is very popular for its ease of use and integration.

winston

The 'winston' package is a multi-transport async logging library for Node.js. It is more feature-rich than 'diagnostics', providing support for multiple storage options, custom log levels, and transports for logging to various outputs such as files, consoles, or remote services.

bunyan

The 'bunyan' package is a simple and fast JSON logging library for Node.js services. It provides features like log rotation, streams, and serializers. It is similar to 'diagnostics' in providing structured logging but differs in its focus on JSON format and log management features.

README

Diagnostics

Diagnostics provides a set of tools that is designed to help you with debugging your Node.js and front-end applications.

Installation

npm install --save diagnostics

We're starting out small but every major release will unlock another piece of the puzzle. The following tools are already at your disposal:

Logging

Logging is something you always need in your applications, if you don't know what's going on, it's damn hard to fix it. This is especially true with async systems when your stack traces are most likely completely useless. In diagnostics we ship a simple logger which can be turned on and off using environment variables. So it's out of the way for your users and there when you need it.

The logger is exposed as function:

var log = require('diagnostics')('example');

log('foo %s', 'bar');

The first argument in the function is the namespace of you log function. All log message will be prefixed with. But we also allow a second argument. This can be used to configure the logger. The following options can be configured:

• color: The color for the namespace, this can be a hex (#FFF) color string or the name of a color. If no color is provided we will generate consistently hashed color from the given namespace and use that instead.
• color**s**: Forcefully enable or disable the use of colors in the log output. If no colors boolean is provided we will determine if it's a proper tty and show colors.
• stream: The stream instance we should write our logs to. We default to process.stdout (unless you change the default using the .to method).
• precise: By default our log timing is rounded up to the nearest number. If you need more precise timing you can set this option to true.

Multiple streams

The beauty of this logger is that it allows a custom stream where you can write the data to. So you can just log it all to a separate server, database and what not. But we don't just allow one stream we allow multiple streams so you might want to log to disk AND just output it in your terminal. The only thing you need to do is either use:

require('diagnostics').to([
  stream1,
  stream2
]);

To set multiple streams as the default streams or supply an array for the logger it self:

var log = require('diagnostics', { stream: [
  stream1,
  stream2
]});

log('foo');

In addition to using the DEBUG environment variable you can also the DIAGNOSTICS environment variable.

License

MIT