librato-rails will report key statistics for your Rails app to Librato Metrics and allow you to easily track your own custom metrics. Metrics are delivered asynchronously behind the scenes so they won't affect performance of your requests.
Currently Rails 3.0+ and Ruby 1.9.2+ are required.
You may want to read the notes on upgrading if you were an alpha tester.
librato-rails and relaunching your application will automatically start the reporting of metrics to your Metrics account.
librato-rails will detect your environment and start reporting available performance information for your application.
Custom metrics can also be added easily:
# keep counts of key events Librato.increment 'user.signup' # easily benchmark sections of code to verify production performance Librato.timing 'my.complicated.work' do # do work end # track averages across requests Librato.measure 'user.social_graph.nodes', user.social_graph.size
If you don't have a Metrics account already, sign up. In order to send measurements to Metrics you need to provide your account credentials to
librato-rails. You can provide these one of two ways:
Use a config file
config/librato.yml like the following:
production: user: <your-email> token: <your-api-key>
librato.yml file is parsed via ERB in case you need to add some host or environment-specific magic.
Note that using a configuration file allows you to specify different configurations per-environment. Submission will be disabled in any environment without credentials.
Use environment variables
Alternately you can provide
LIBRATO_TOKEN environment variables. Unlike config file settings, environment variables will be used in all non-test environments (development, production, etc).
Note that if a config file is present, all environment variables will be ignored.
For more information on combining config files and environment variables, see the full configuration docs.
Running on Heroku
If you are using the Librato Metrics Heroku addon, your user and token environment variables will already be set in your Heroku environment. If you are running without the addon you will need to provide them yourself.
In either case you will need to specify a custom source for your app to track properly. If
librato-rails does not detect an explicit source it will not start. You can set the source in your environment:
heroku config:add LIBRATO_SOURCE=myappname
If you are using a config file, add your source entry to that instead.
Full information on configuration options is available on the configuration wiki page.
Note that if Heroku idles your application measurements will not be sent until it receives another request and is restarted. If you see intermittent gaps in your measurements during periods of low traffic this is the most likely cause.
librato-rails and restarting your app and you will see a number of new metrics appear in your Metrics account. These track request performance, sql queries, mail handling, and other key stats.
Built-in performance metrics will start with either
rails, depending on the level they are being sampled from. For example:
rails.request.total is the total number of requests rails has received each minute.
Tracking anything that interests you is easy with Metrics. There are four primary helpers available:
Use for tracking a running total of something across requests, examples:
# increment the 'sales_completed' metric by one Librato.increment 'sales_completed' # increment by five Librato.increment 'items_purchased', :by => 5 # increment with a custom source Librato.increment 'user.purchases', :source => user.id
Other things you might track this way: user signups, requests of a certain type or to a certain route, total jobs queued or processed, emails sent or received
Sporadic Increment Reporting
increment is primarily used for tracking the rate of occurrence of some event. Given this increment metrics are continuous by default: after being called on a metric once they will report on every interval, reporting zeros for any interval when increment was not called on the metric.
Especially with custom sources you may want the opposite behavior - reporting a measurement only during intervals where
increment was called on the metric:
# report a value for 'user.uploaded_file' only during non-zero intervals Librato.increment 'user.uploaded_file', :source => user.id, :sporadic => true
Use when you want to track an average value per-request. Examples:
Librato.measure 'user.social_graph.nodes', 212 # report from a custom source Librato.measure 'jobs.queued', 3, :source => 'worker.12'
Librato.measure this is per-request, but specialized for timing information:
Librato.timing 'twitter.lookup.time', 21.2
The block form auto-submits the time it took for its contents to execute as the measurement value:
Librato.timing 'twitter.lookup.time' do @twitter = Twitter.lookup(user) end
There is also a grouping helper, to make managing nested metrics easier. So this:
Librato.measure 'memcached.gets', 20 Librato.measure 'memcached.sets', 2 Librato.measure 'memcached.hits', 18
Can also be written as:
Librato.group 'memcached' do |g| g.measure 'gets', 20 g.measure 'sets', 2 g.measure 'hits', 18 end
Symbols can be used interchangably with strings for metric names.
You can set an optional prefix to all metrics reported by
librato-rails in your configuration. This can be helpful for isolating test data or forcing different apps to use different metric names.
librato-rails submits measurements back to the Librato platform on a per-process basis. By default these measurements are then combined into a single measurement per source (default is your hostname) before persisting the data.
For example if you have 4 hosts with 8 unicorn instances each (i.e. 32 processes total), on the Metrics site you'll find 4 data streams (1 per host) instead of 32. Current pricing applies after aggregation, so in this case you will be charged for 4 streams instead of 32.
If you want to report per-process instead, you can set
your config, which will append the process id to the source name used by each thread.
Note that it may take 2-3 minutes for the first results to show up in your Metrics account after you have started your servers with
librato-rails enabled and the first request has been received.
If you want to get more information about
librato-rails submissions to the Metrics service you can set your
debug (see configuration) to get detailed information added to your logs about the settings
librato-rails is seeing at startup and when it is submitting.
If you are having an issue with a specific metric, using a
trace will add the exact measurements being sent to your logs along with lots of other information about
librato-rails as it executes. Neither of these modes are recommended long-term in production as they will add quite a bit of volume to your log file and will slow operation somewhat. Note that submission I/O is non-blocking, submission times are total time - your process will continue to handle requests during submissions.
If you are debugging setting up
librato-rails locally you can set
flush_interval to something shorter (say 10s) to force submission more frequently. Don't change your
flush_interval in production as it will not result in measurements showing up more quickly, but may affect performance.
- Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
- Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
- Fork the project and submit a pull request from a feature or bugfix branch.
- Please include tests. This is important so we don't break your changes unintentionally in a future version.
- Please don't modify the gemspec, Rakefile, version, or changelog. If you do change these files, please isolate a separate commit so we can cherry-pick around it.
Copyright (c) 2012-2013 Librato Inc. See LICENSE for details.