Metrux

An instrumentation library which persists the metrics on InfluxDB.

Summary

1. Installation
2. Configuration
   1. Configuration Keys
3. Usage
   1. Write
   2. Meter
   3. Gauge
   4. Periodic Gauge
   5. Timer
   6. Notice Error
   7. Plugins
      1. Registering

Installation

Add this line to your application's Gemfile:

gem 'metrux'

And then execute:

$ bundle

Or install it yourself as:

$ gem install metrux

Configuration

You will need to create a config file on config/metrux.yml. See a sample here.

Its configuration is based on ENV VARS and/or YAML, pretty similar to appsignal or newrelic gems. ENV VARS will always override yaml configs.

If you want to configure only via ENV VARS you won't need to have the config file.

Configuration keys

ENV VAR	yaml	Default	Description
METRUX_ACTIVE	active	false	Whether it is active. Can be true or false
METRUX_APP_NAME	app_name		Your application's name (All metrics will be marked with this tag)
METRUX_PERIODIC_GAUGE_INTERVAL	periodic_gauge_interval	60	Interval that agent will execute all registered periodic gauges (in seconds)
METRUX_LOG_FILE	log_file	STDOUT	Log file path
METRUX_LOG_LEVEL	log_level	info	Log level
METRUX_INFLUX_HOST	influx_host	localhost	InfluxDB host - See: https://github.com/influxdata/influxdb-ruby#creating-a-client
METRUX_INFLUX_PORT	influx_port	8083	InfluxDB port
METRUX_INFLUX_DATABASE	influx_database		InfluxDB database
METRUX_INFLUX_USERNAME	influx_username	root	InfluxDB username
METRUX_INFLUX_PASSWORD	influx_password	root	InfluxDB password
METRUX_INFLUX_ASYNC	influx_async	true	InfluxDB async options - See: https://github.com/influxdata/influxdb-ruby#writing-data

Usage

Before you start sending your metrics to InfluxDB, is very important that you read InfluxDB Schema Design for a better understanding of how to use tags and fields.

All writes will automatically include the tags app_name, hostname, env and program_name unless you pass another value.

All measurement keys will have the prefix of the app name (app_name.underscore).

Write

Writes a point.

Single value/field

key = 'my_awesome_key'
data =  1

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.write(key, data, options)

Result:

name: app_name/my_awesome_key
--------------------
time                    app_name      hostname       something       value
1466604892000000000     Your appname  YOURHOSTNAME   a-string-value  1

Multi value/field

key = 'my_awesome_key'
data =  { another_field: 1, value: 2 }

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.write(key, data, options)

Result:

name: app_name/my_awesome_key
--------------------
time                    app_name      hostname       another_field  something       value
1466604892000000000     Your appname  YOURHOSTNAME   1              a-string-value  2

Meter

Writes a meter (aka counter). All meters' key will have the prefix meters/.

Simple increment (value: 1)

key = 'my_meter'

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.meter(key, options)

Result:

name: app_name/meters/my_meter
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  1

Different increment (value <> 1)

key = 'my_meter'

value = 5

# Options are not required
options = {
  value: value, tags: { something: 'a-string-value' }, precision: 's'
}

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.meter(key, options)

Result:

name: app_name/meters/my_meter
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  5

Gauge

Writes a gauge (result of something). All gauges' key will have the prefix gauges/.

Execute a block and save its result

key = 'my_gauge'

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.gauge(key, options) { 40 }
# => 40

Result:

name: app_name/gauges/my_gauge
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  40

The rule for multi value/field is the same of write.

Just save the result of a previously executed block

key = 'my_gauge'

result = 42

# Options are not required
options = {
  result: result, tags: { something: 'a-string-value' }, precision: 's'
}

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.gauge(key, options)
# => 42

Result:

name: app_name/gauges/my_gauge
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  42

The rule for multi value/field is the same of write.

Periodic gauge

Executes periodically a gauge (result of something) and writes it. All periodic gauges' key will have the prefix gauges/.

The interval of each execution will depend on the configuration. See Configuration.

Remember that gauges must be lightweight and very fast to execute.

key = 'my_periodic_gauge'

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.periodic_gauge(key, options) { Thread.list.count }

Result after having passed (interval * 1) seconds:

name: app_name/gauges/my_gauge
---------------------
time                    app_name      hostname          something       value
1466609741000000000     Your appname  YOURHOSTNAME      a-string-value  6

Result after having passed (interval * 2) seconds:

name: app_name/gauges/my_gauge
---------------------
time                    app_name      hostname          something       value
1466609741000000000     Your appname  YOURHOSTNAME      a-string-value  6
1466609746000000000     Your appname  YOURHOSTNAME      a-string-value  6

The rule for multi value/field is the same of write.

Timer

Calculates and writes the time elapsed of something. All timers' key will have the prefix timers/.

Execute a block and save its execution time

key = 'my_timer'

# Options are not required
options = { tags: { something: 'a-string-value' }, precision: 's' }

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.timer(key, options) { sleep(0.45); 40 }
# => 40

Result:

name: app_name/timers/my_timer
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  455

Just save the duration of a previously calculated block

key = 'my_timer'

duration = 1342 # milliseconds

# Options are not required
options = {
  duration: duration, tags: { something: 'a-string-value' }, precision: 's'
}

# options[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

Metrux.timer(key, options)
# => nil

Result:

name: app_name/timers/my_timer
---------------------
time                    app_name      hostname          something       value
1466604892000000000     Your appname  YOURHOSTNAME      a-string-value  1342

Notice error

Meters errors.

def do_something(a, b)
  raise(ArgumentError, 'Some message') if b = 0
rescue => e
  # Args are not required
  args = { a: a, b: b, uri: 'http://domain.tld/path' }

  # args[:timestamp] = Time.now.to_i # you can also provide a custom timestamp

  Metrux.notice_error(e, args)

  raise
end

do_something(1, 0)

Result:

name: app_name/meters/errors
---------------------
time                 a  app_name       b  error           hostname       message       uri                       value
1466608927000000000  1  Your appname   0  ArgumentError   YOURHOSTNAME   Some message  "http://domain.tld/path"  1

Plugins

• Metrux::Plugins::Thread - Register a periodic gauge to count the amount of running threads. See Metrux::Plugins::Thread
• Metrux::Plugins::Gc - Register a periodic gauge to fetch info from Ruby's GC. See Metrux::Plugins::Gc
• Metrux::Plugins::Process - Register a periodic gauge to fetch the memory consumption (rss) of the current process. See Metrux::Plugins::Process
• Metrux::Plugins::Yarv - Register a periodic gauges to fetch info from Ruby's VM. See Metrux::Plugins::Yarv

Registering

You need to register the plugins to have them working. It's also possible to register your own plugins on Metrux:

module Metrux
  module Plugins
    class MyAwesomePlugin
      def initialize(config, options); @config, @options = config, options; end

      def call
        Metrux.periodic_gauge('threads_count', @options) { Thread.list.count }
      end
    end
  end
end

plugin = Metrux::Plugins::MyAwesomePlugin
options = { my: { plugin: :options } }

Metrux.register(plugin, options) # => true

Or you can use a Proc instead of a class:

options = { my: { plugin: :options } }

Metrux.register(options) do |config, options|
  Metrux.periodic_gauge('threads_count', options) { Thread.list.count }
end # => true

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bin/rspec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bin/rake install. To release a new version, update the version number in version.rb, and then run bin/rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

License

The gem is available as open source under the terms of the MIT License.

Git tags

Don't forget to tag your work! After a merge request being accepted, run:

1. (git tag -a "x.x.x" -m "") to create the new tag.
2. (git push origin "x.x.x") to push the new tag to remote.

Follow the RubyGems conventions at http://docs.rubygems.org/read/chapter/7 to know how to increment the version number. Covered in more detail in http://semver.org/

Pull requests acceptance

Don't forget to write tests for your changes. It's very important to maintain the codebase's sanity. Any pull request that doesn't have enough test coverage will be asked a revision.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request