Koa-grace-logger NPM

koa-logger2

Logger middleware for http://github.com/koajs. Inspired by morgan from expressjs and apache.

Usage

Simplest example that will print basic information to standard output:

var logger = require('koa-logger2');
app.use(logger().gen); // will log to standard output by default

More advanced usage which will output more apache-like combined log:

var logger = require('koa-logger2');

var log_middleware = logger('ip [day/month/year:time zone] "method url protocol/httpVer" status size "referer" "userAgent" duration ms custom[unpacked]');
log_middleware.setStream(fs.createWriteStream(path.join(__dirname, 'logs/2014-09.log'), { flags: 'a' }));

app.use(log_middleware.gen); // !! note there are no () after gen

As a result you will get lines like:

123.45.67.89 [12/Sep/2014:22:12:26 +0200] "GET / HTTP/1.1" 301 22 "-" "Mozilla/5.0 (Android; Mobile; rv:31.0) Gecko/31.0 Firefox/31.0" 0 ms -

Later at any time you can call setStream again in order to replace stream you're writing to.

API

Just call the only function which is being exported:

logger( format = " day/month time ip "method url protocol/httpVer" status size "referer" "userAgent" duration ms " )

This will create logger object which has two properties - setStream method and gen. Formatters currently implemented are:

Formatter	Description (Example)
ip	IP address of the client
method	Request method (GET)
url	Request url (/)
status	Status code (200)
httpVer	Protocol version (1.1)
protocol	HTTP or HTTPS
size	Content-Length of response
referer	Referer header
userAgent	User-agent header
time	Current time in 24-hour format HH:MM:SS
day	Day of month 01-31
month	Short month name (Sep)
year	Year 4 digits (2014)
zone	Timezone offset (+0200)
duration	Duration of processing this request
customyour.field	Basically access anything you want from koa (ctx) object

setStream( stream.Writable )

Use this function to replace output stream for the logger (for example for log rotation). Please keep in mind that actual writing to the stream happens "on the way back".