l2met supports one-time event syntax

[josephruscio]

Many metric systems support the concept of correlating one-time or aperiodic events against their metrics, commonly as vertical lines overlaid on a line chart (e.g. Librato Annotations)

An example of such an event is Heroku's release notifications that occur whenever new code is pushed to a Heroku application:

2013-07-06T12:00:01+00.00 heroku[api]: Release v3 created by email@example.com

l2met should support a format for parsing events from the log stream and pushing them to the metrics backend. This ideally would support a rich event type e.g. Librato's Annotation definition. /cc @nextmat @mheffner

[mattreduce]

@ryandotsmith What's a sane format for me to suggest Add-on providers use? How about the following:

event#title=deployed event#start_time=1234567890 event#link.href=https://github.com/acme/app/commits/01beaf

This is inspired by the Librato docs that @josephruscio mentioned.

[ryandotsmith]

@mattonrails nice. One quick observation... The time is included in the syslog packet's header per RFC5424. So it is not necessary to include a start_time as long as the emitter emits the log line when the event actually started.

[ryandotsmith]

Man, so excited to get Heroku's deploy events on this syntax. I am dying to have my dyno restart and deploys annotated on my charts.

[jamischarles]

+100 :)

[aseemk]

Love the idea.

[aseemk]

Suggestion for syntax, if timestamp isn't needed, and to be more consistent w/ existing metric syntax:

event#name=arbitrary-value

E.g. in the case of Heroku deploys, could be a release number:

event#release=v123

This is a nice and terse syntax, but is obviously limiting if you want to associate more info. But that's the trade-off l2met has already taken with its existing metric syntax.