Flog

Logfile automation for JSON logs.

var logamaton = require('logamaton');

var entries = logamaton({
  readStream: fs.createReadStream('./logs.json'),
});

entries
  .filter(logamaton.filters.all())
  .filter(logamaton.filters.after({
    start: new Date('2014-01-01')
  }))
  .filter(logamaton.filters.has('err'))
  .report(function (results) {
    console.log(results);
  });

Installation

$ npm install logamaton

Filters

Determine whether a given entry from a log is interesting or not. All filters are instrumented to capture a count of all log entries they receive and a copy of all entries they match. They may be defined either as arguments to logamaton:

var filters = [
  logamaton.filters.all(),
  logamaton.filters.after({ start: new Date('2014-03-18T02:14:39.151Z') }),
  logamaton.filters.has('err'),
  logamaton.filters.where({ level: 40 })
];

logamaton({
  readStream: process.stdin,
  filters: filters
});

Or by chaining with filter:

logamaton({ readStream: process.stdin });
  .filter(logamaton.filters.all())
  .filter(logamaton.filters.after({ start: new Date('2014-03-18T02:14:39.151Z') }));

Custom Filters

Custom filters may be built using logamaton.instrument(name, iter):

var fzbz = logamaton.instrument('fzbz', function (data, callback) {
  data.fizz = 'buzz';
  callback(null, data);
});

Reporters

Reporters inspect filter metrics to summarize the contents of the log. They may be defined either as arguments to logamaton:

function aReporter (results) {
  console.log(results.total);
}

logamaton({
  readStream: process.stdin,
  filters: filters,
  reports: [aReporter]
});

Or by chaining with report:

logamaton({ readStream: process.stdin })
  .report(function (results) {
    console.log(results.total);
  })

Reports for an individual function may also be recovered from a specific filter by calling results() on the filter.

var after = logamaton.filters.after({
  start: new Date('2014-03-18T02:14:39.151Z')
});

logamaton({ readStream: process.stdin })
  .filter(after)
  .report(function () {
    console.log(after.results().matches);
  });

TODO

More filtering, more reporting, more analytics. Test coverage. Benchmarking.

Contributing

Have something to add? Contributions are enormously welcome!

1. Fork this repo
2. Update the spec and implement the change
3. Submit a pull request

License

Flog is released under the terms of the JSON license