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About the developer

pablosichert
399 Stars 14 Forks MIT License 113 Commits 2 Opened issues

Description

Log HTTP requests/responses separately, visualize their concurrency and report logs/errors in context of a request

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concurrency-logger

NPM version Build status Coverage status Dependency status Dev dependency status

HTTP logging middleware especially useful to unwind concurrent operations without losing the request context

HTTP logs in a terminal, visualizing server status codes, response times, debug information and errors for concurrent requests
Launch demo in your browser

Install

$ npm install concurrency-logger

Usage

With koa

Basic usage

import Koa from 'koa';
import createLogger from 'concurrency-logger';

const app = new Koa;

// Logger is stateful as it contains information about concurrent requests // Same instance needs to be reused across requests const logger = createLogger(/* options */);

app.use(logger);

Log from middleware

// Log something in context to a specific request to trace it back easily -
// also when there are multiple concurrent requests
app.use(async (context, next) => {
    context.log('Log!');
    context.log.info('Info!');
    context.log.error('Error!');

await next();

});

Attach more context to the log

const logger = createLogger({
    req: context => (
        context.originalUrl + '\n' +
        context.get('User-Agent')
    )
});

Include localized timestamps

const logger = createLogger({
    timestamp: true
});

Write log to file

import { createWriteStream } from 'fs';

// To read log use program that interprets ANSI escape codes, // e.g. cat or less -r const log = createWriteStream('logs/requests.log');

const logger = createLogger({ reporter: log });

Adjust alert levels per method and response time

const logger = createLogger({
    getLevel: (responseTime, context) => {
        /*
            GET
              0 -  99ms: 0
            100 - 149ms: 1
            150 - 199ms: 2
            200 - 249ms: 3
            250 - 299ms: 4
            300 - 349ms: 5
            > 350ms    : 6

        POST
          0 - 149ms: 0
        150 - 225ms: 1
               ... : ...
    */

    let threshold = 50; // ms

    if (['POST', 'PUT'].includes(context.method)) {
        threshold *= 1.5;
    }

    return Math.floor(responseTime / threshold) - 1;
}

});

Standalone

import createLogger from 'concurrency-logger';

const logger = createLogger(/* options */);

(async () => { const context = { method: 'GET', originalUrl: '/' };

const next = async () => {
    await new Promise(resolve => setTimeout(resolve, 100));

    context.status = 200;
};

try {
    await logger(context, next);
} catch (error) {
    // Errors are passed through
}

})();

API

| Option | Type | Default | Description | Example | | ---- | ---- | ------- | ----------- | ------- | | minSlots | integer |

1
| Amount of space that is provisioned to display concurrent request lanes. Number of lanes will automatically scale up as the number of concurrent requests grow. |
3
| getLevel | integer: function(responseTime: integer) |
responseTime => Math.floor(responseTime / 50) - 1
| Map response time to alert level. Alert levels go from 0 (default color) to 6 (dark red). By default that means
<100ms: 0
,
<150ms: 1
<200ms: 2
, ...,
>=350ms: 6
. |
responseTime => Math.floor(responseTime / 100)
| width | integer, boolean(
false
) |
undefined
| If no width is provided, it will be dynamically read from
process.stdout.columns
. Pass in an integer to break all lines according to the specified fixed (terminal character) width. Pass in
false
if you want the lines not to break at all. |
80
,
132
,
false
| timestamp | boolean |
false
| Print localized timestamp for every requests. |
true
,
false
| slim | boolean |
false
| "Slim mode": don't use an extra character between request lanes to shrink width, but make them harder to separate visually. |
true
,
false
| reporter | writable stream |
process.stdout
| Specify a stream that handles the output lines. Write to terminal or stream to a log file, for example. Note that the lines contain ANSI color codes, so when streaming to a file you might need a program that can read those. E.g.
less -r requests.log
|
require('fs').createWriteStream('logs/requests.log')
| req | any: function(context: object) |
context => context.originalUrl
| Attach additional information to the request log line. |
context => context.originalUrl + '\n' + context.get('User-Agent')
| res | any: function(context: object) |
context => context.originalUrl
| Attach additional information to the response log line. |
context => context.originalUrl + '\n' + context.get('User-Agent')

Developing

Install development dependencies

$ npm install

Create new fixtures to test against

$ npm run create-fixtures

Manually review fixtures (you need a program that renders ANSI escape codes)

$ less -r test/fixtures/*

Run tests

$ npm test

Run code linter

$ npm run lint

Compile to ES5 from /src to /lib

$ npm run compile

Initialize demo project

$ git clone [email protected]:PabloSichert/concurrency-logger demo
$ cd demo
demo $ git checkout gh-pages
demo $ npm install

Build demo

demo $ npm run compile

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