logfmt

node-logfmt

install

npm install logfmt

use

var logfmt = require('logfmt');

logging

logfmt.log()

Defaults to logging to process.stdout

var logfmt = require('logfmt');
logfmt.log({ "foo": "bar", "a": 14, baz: 'hello kitty'})
//=> foo=bar a=14 baz="hello kitty"

customizing logging location

log() Accepts as 2nd arg anything that responds to write(string)

var logfmt = require('logfmt');
logfmt.log({ "foo": "bar", "a": 14, baz: 'hello kitty'}, process.stderr)
//=> foo=bar a=14 baz="hello kitty"

Overwrite the default location by setting .stream

var logfmt = require('logfmt');
logfmt.stream = process.stderr

logfmt.log({ "foo": "bar", "a": 14, baz: 'hello kitty'})
//=> foo=bar a=14 baz="hello kitty"

parser

logfmt.parse()

var logfmt = require('logfmt');

logfmt.parse("foo=bar a=14 baz=\"hello kitty\" cool%story=bro f %^asdf code=H12")
//=>{ "foo": "bar", "a": 14, "baz": "hello kitty", "cool%story": "bro", "f": true, "%^asdf": true, "code" : "H12" }

express middleware

Requires express to be installed

Streaming

If you use the logfmt.bodyParserStream() for a body parser, you will have a req.body that is a readable stream.

var app    = require('express')();
var http   = require('http');
var logfmt  = require('logfmt');

app.use(logfmt.bodyParserStream());

// req.body is now a Readable Stream
app.post('/logs', function(req, res){
  req.body.on('readable', function(){
    var parsedLine = req.body.read();
    if(parsedLine) console.log(parsedLine);
    else res.send('OK');
  })
})

http.createServer(app).listen(3000);

var app    = require('express')();
var http   = require('http');
var through = require('through');
var logfmt  = require('logfmt');

app.use(logfmt.bodyParserStream());

app.post('/logs', function(req, res){
  if(!req.body) return res.send('OK');

  req.body.pipe(through(function(line){
    console.dir(line);
  }))

  res.send('OK');
})

http.createServer(app).listen(3000);

Non-Streaming

If you use the logfmt.bodyParser() for a body parser, you will have a req.body that is an array of objects.

var logfmt   = require('logfmt');

app.use(logfmt.bodyParser());

// req.body is now an array of objects
app.post('/logs', function(req, res){

  console.log('BODY: ' + JSON.stringify(req.body));

  req.body.forEach(function(data){
    console.log(data);
  });

  res.send('OK');
})

http.createServer(app).listen(3000);

test it:

curl -X POST --header 'Content-Type: application/logplex-1' -d "foo=bar a=14 baz=\"hello kitty\" cool%story=bro f %^asdf" http://localhost:3000/logs

command line

accepts lines on STDIN and converts them to json

echo "foo=bar a=14 baz=\"hello kitty\" cool%story=bro f %^asdf" | logfmt
{ "foo": "bar", "a": 14, "baz": "hello kitty", "cool%story": "bro", "f": true, "%^asdf": true }

reverse

accepts JSON on STDIN and converts them to logfmt

echo '{ "foo": "bar", "a": 14, "baz": "hello kitty", "cool%story": "bro", "f": true, "%^asdf": true }' | logfmt -r
foo=bar a=14 baz="hello kitty" cool%story=bro f=true %^asdf=true

echo "foo=bar a=14 baz=\"hello kitty\" cool%story=bro f %^asdf" | logfmt | logfmt -r | logfmt
{ "foo": "bar", "a": 14, "baz": "hello kitty", "cool%story": "bro", "f": true, "%^asdf": true }