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    concurrency-logger

    2.1.0 • Public • Published

    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 git@github.com:PabloSichert/concurrency-logger demo
    $ cd demo
    demo $ git checkout gh-pages
    demo $ npm install
    

    Build demo

    demo $ npm run compile
    

    Install

    npm i concurrency-logger

    DownloadsWeekly Downloads

    183

    Version

    2.1.0

    License

    MIT

    Unpacked Size

    20.6 kB

    Total Files

    4

    Last publish

    Collaborators

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