volleyball

🏐 Volleyball

Small Express HTTP logger for debugging asynchronous requests and responses

const app = require('express')()
const volleyball = require('volleyball')

app.use(volleyball)

Volleyball is a minimal Connect-style middleware function which logs incoming requests and outgoing responses as separate events. It optionally supports the debug module.

Motivation

Logging HTTP cycles can be approached in several ways, each with its own drawbacks:

• Log only upon request. Drawback: we cannot log the corresponding response, which happens later (if at all).
• Log only upon response, attaching the request. Drawback A: if the server never sends a response, e.g. due to a bug, the request will not be logged either. Drawback B: two temporally distinct events are conflated, misleadingly.
• Log both upon request and response. Drawback: it is not necessarily clear which responses are for which requests.

Volleyball takes the last approach, and assigns randomly-generated ids to label request-response pairs. It is designed for student project development, teaching beginning programmers how HTTP servers and asynchronicity work. It may also be useful as a low-configuration debug tool.

Usage

volleyball

The volleyball module can be used directly as demonstrated in the first example. The module defaults to using process.stdout for output.

volleyball.custom(config)

A customized logging middleware can be generated by calling custom with a configuration object:

const logger = volleyball.custom({ debug: true }) // default namespace 'http'
// const logger = volleyball.custom({ debug: 'custom-namespace' })
// const logger = volleyball.custom({ debug: debugInstance })

app.use(logger)

The debug property logs using the debug module. It supports the following values:

value	result
true	uses a new debug instance with a default namespace of 'http'
string	uses a new debug instance with a custom namespace
function	uses any function, such as a pre-generated debug instance. Note that the function will be called with colorized strings.

Related and Alternatives

For more powerful, configurable, and compatible logging needs, check out:

• debug
• morgan
• morgan-debug
• winston
• express-winston
• node-bunyan