Metriclient - Flexible event and error reporting server
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Flexible event and error reporting server

About metriclient

Metriclient is a specification for storing structured data to represent events and errors coming from your application. It comes bundled with a server to store them, and a set of scripts to help you extract information from it.

It is designed to be an independent server that specializes on error recollection. It plays well with Lithium and Cobalt, since they are designed for execution tracing and message formatting themselves, but they are not required.

Events and errors

Events are the central component in metriclient. They are data records that contain the information you want to track.

The structure of an event is:


Errors are no different than events, but are more specialized events that come with more information about the errors on your application. They are recorded in a different table, and have more fields that reflect the nature of an error or can aid in detecting and debugging, such as line, url and user_agent

The fields for an error are:


Field description

  • id, created_at, updated_at: Standard sql id and timestamps
  • event_type: Send the name of the event you are interested in (e.g.: 'login_button:click').
  • error: String that holds the error message, passed from the client.
  • url: Intended for error catching in the frontend, this holds the url where the error comes from.
  • user_agent: Also for frontend error catching, pass the user agent from where the request originated.
  • scoped_class_name: When using Lithium error catching, this indicates the Neon class where it originated.
  • frame: Defines the scope or module in which the error generated, not necessarily HTML frame but application frame.
  • meta: This can hold arbitrary data you want to send from your application. The errors table saves the meta info as text, so it works best for unstructured data (suck as error stack traces). For structured data, you may want to look at the Meta table

Meta table

Aside from the standard event fields, you can store any arbitrary structured data in the events_meta table. The metriclient API does the extraction automatically if you pass an object to the meta attribute

The event_meta table holds the following fields:

  • id: Standard sql id
  • key: The name of the key in the metadata
  • value: The value associated with the key coming from the metadata
  • event_id: Foreign key referencing the event from which this meta info comes from


The metriclient API consists of the following methods

POST /api/v1/events


event: A JSON object containing all the required fields for the event. It can also contain the special field data, to store metaadata related to the event.

POST /api/v1/errors

event: A JSON object containing all the required fields for the error.

and the web view for errors

GET /errors/:id

Shows the json object of the record with that id


id: The id of the error record


The metriclient server comes bundled with scripts for archiving, since it is expected that you'd want to store a large number of events and errors.

You can use the rake tasks for manually making archive backups of your database, or integrate them with your deploy and provisioning system for scheduling them.

The data is archived in tables named events_archive, events_meta_archive and errors_archive with the same schema as the original tables.

It is recommended that you use an ARCHIVE storage engine for the database since the archive is intended for read-only, there are no updates and inserts are on demand


$ ./script/db/archive config/myproject.yml
$ ./script/db/clean   config/myproject.yml

# Example of myproject.yml:
# -------------------------------------------------------------------------
# host      : localhost
# database  : metriclient_dev
# username  : root
# password  :
# tables    :
#   archive:  [events, errors, event_meta]
#   clean:  [events, errors]
# -------------------------------------------------------------------------

You should add something similar to your provisioning engine. Probably in a cron or something, it is up to you to setup the right env though.

Note: We recommend archiving every hour, and cleaning once a day.

Note: MySQL dumps fall outside of this app's realm, you should provision that yourself!

Simple event tracking

Send event info to the API, from a node.js client

var request = require("request");

    uri : '',
    method: 'POST',
    form: {
        event: {
            event_type: 'user:login',
            data: {
                userId: 10,
                siteVersion: '1.0'
}, function(error, response, body) {

Frontend Error tracking

In this example you can set up error catching and send detailed info to the server. The example is using Lithium, but you can use it with try/catch or standard onError events.

Li.Engine.error.push(function (data) {
    var className = data.spy.targetObject.className || data.scope.constructor.className;
    var methoName = data.spy.methodName;
    $.post('', {
        data : {
            event : {
                userAgent : navigator.userAgent,
                scopedClassName : className,
                error : data.error.message,
                meta : data.error.stack
        success : { ... }


For installing, first you need to create your config/database.yml file, with your database settings. The keys should be the name of your subdomains if want to have multiple projects reporting to different subdomains in the same server. For using just one database without subdomains, you can use the default key.

    adapter: mysql2
    database: database_name
    username: user
    password: 123abc
    host: localhost
    adapter: mysql2
    database: metriclient
    username: root
    password: 123abc
    host: localhost


Then you need to create the database and run the migrations

$ RACK_ENV=production rake db:create
$ RACK_ENV=production rake db:migrate

This will set up the database. Only thing left you need is to run the server, using whatever web server you decide

$ RACK_ENV=production unicorn_rails -c config/unicorn.rb