hashmonitor

HashMonitor: Turn Logs Into Metrics Like A Boss

HashMonitor is a simple way to turn your logs into metrics by using hashtags in your log messages.

How does it work?

By default, HashMonitor reads text lines from stdin, and every 30 seconds writes JSON statistics to stdout. You can pipe this JSON output into your favorite stats dashboard (tinyfeedback, statsd, etc) for easy visualization.

Example: counting warning events

For example, you could keep track of warnings in your application by simply logging with a #warn hashtag:

log("something weird happened #warn")
log("something odd happened #warn")
log("something strange happened #warn")

HashMonitor will read your log file line-by-line, and count the number of #warn events:

{ warn: { count: 3 } }

Example: watching performance metrics

You can also track value-based metrics by assigning a numeric value to your hashtags:

log("speed was pretty fast #loaded_in_seconds=3")
log("speed was pretty fast #loaded_in_seconds=2")
log("something was slowwww #loaded_in_seconds=17")

HashMonitor will read your log file line-by-line, and count the number of #loaded_in_seconds events as well as other statistics:

{ loaded_in_seconds: 
   { count: 3,
     mean: 7.333333333333333,
     stddev: 6.847546194724712,
     x01: 17,
     x10: 17,
     median: 2,
     x90: 3,
     x99: 3,
     min: 17,
     max: 3 } }

How can I try it out?

Easiest is installing hashmonitor globally:

$ sudo npm install -g hashmonitor

Then just run the HashMonitor using the default stdin/stdout:

$ hashmonitor

Once you are here, just type some fake log messages into stdin:

hello #world
goodnight #moon
over the #moon

After 30 seconds you will see JSON stats output, like:

{ world: { count: 1 }, moon: { count: 2 } }

The counts are reset with each stats output. You can also try out value-based metrics:

slow stuff #loadtime=25
fast stuff #loadtime=10

Instead of just seeing counts now, you will also see additional stats about the distribution of these values:

{ loadtime: 
   { count: 2,
     mean: 17.5,
     stddev: 7.5,
     x01: 10,
     x10: 10,
     median: 25,
     x90: 25,
     x99: 25,
     min: 10,
     max: 25 } }

There ya go Boss!