Third party instrumentation

The simplest way to get a transaction started is to call add_transaction_tracer on the method. This assumes that NewRelic::Agent::Instrumentation::ControllerInstrumentation is included in your class.

class CustomBackgroundJob
  include NewRelic::Agent::Instrumentation::ControllerInstrumentation

  def transaction
    # execute a transaction
  end

  add_transaction_tracer :transaction
end

Sometimes you need slightly more control over the transaction that New Relic generates. When that happens, you can use perform_action_with_newrelic_trace. Some of the parameters you can override include the transaction name and category (whether it's a web transaction or a background transaction).

class CustomBackgroundJob
  include NewRelic::Agent::Instrumentation::ControllerInstrumentation

  def transaction
   perform_action_with_newrelic_trace(:name    => "custom_name",
                                     :category => :task) do
     # your work here...
   end
  end

end

See the full documentation of perform_action_with_newrelic_trace for further information on parameters and usage.

require 'new_relic/agent/method_tracer'
class Foo
  include ::NewRelic::Agent::MethodTracer

  def generate_image
    # ...
  end

  add_method_tracer :generate_image, 'Custom/generate_image'
end

The above example results in metrics being recorded for the name 'Custom/generate_image', as well as an entry in transaction traces that includes the method call.

trace is the simplest way to record Datastore for a method.

class FauxDB

 def find
   # FauxDB lookup
 end

 NewRelic::Agent::Datastores.trace self, :find, "FauxDB"

end

The first parameter is the class to instrument, the second the method to find, the third the datastore product name. An optional operation name can be included as the final parameter, otherwise the method name is used to represent the operation in metrics.

Note that Datastore metrics recorded with this interface do not allow for adding a collection/table name. For that, see the wrap method below.

wrap allows for recording Datastore metrics with additional collection/table information in the metric names. It also provides a callback for operations such as noticing slow statements.

class FauxDB

  def find(table)
    NewRelic::Agent::Datastores.wrap("FauxDB", "find", table) do
    # FauxDB lookup
    end
  end

end

If you want to record additional information about your datastore call, you can use the optional callback parameter on wrap:

class FauxDB

 def find(query)
   callback = Proc.new do |result, scoped_metric, elapsed|
     NewRelic::Agent::Datastores.notice_sql(query, scoped_metric, elapsed)
   end

   NewRelic::Agent::Datastores.wrap("FauxDB", "find", "items", callback) do
     # execute query
   end
 end

end

This helper method records slow SQL queries for presentation in transaction traces and slow SQL pages. SQL is filtered and obfuscated based on the user's settings.

NewRelic::Agent::Datastores.notice_sql(query, scoped_metric, elapsed)

Non-SQL queries should never be sent through notice_sql.Use notice_statement instead.

This helper method records statements for slow datastore calls to transaction traces. These are not obfuscated.

NewRelic::Agent::Datastores.notice_statement(statement, elapsed)

SQL queries should never be sent through notice_statement. Use notice_sql instead.

The test methods documented in this section can be accessed by calling this from your test code (most commonly a test_helper.rb file)

NewRelic::Agent.require_test_helper

This method is the primary way to ensure your expected metrics are recorded by the Ruby agent. refute_metrics_recorded is also available.

In the simplest form, assert_metrics_recorded can be called like this:

assert_metrics_recorded(["MetricA", "MetricB"])

Metrics with specific values can be asserted via this syntax:

assert_metrics_recorded('MetricA' => {
                         :call_count => 1,
                         :total_call_time => 1.0 })

These methods simulate running in web or background transaction.

in_web_transaction do
  # Perform work to test behavior in transaction
end

Configuration of the agent can be changed for testing via with_config. It takes a hash which is applied to the other configuration values in agent.

with_config(:enabled => false) do
  # Check what happens when agent's disabled
end

If you need to test your extension against multiple gem versions, you can use Multiverse, a part of the Ruby agent's own testing code. For examples of Multiverse testing, see the suites directory in the agent files.

To configure Multiverse for your own gem:

1. Require tasks/multiverse in Rakefile. To enable the rake test:multiverse command, add the following to your Rakefile:

   require "tasks/multiverse"

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2. Create the Multiverse test directory. Multiverse tests require a specific file layout. Create a directory named test/multiverse/YOUR_PROJECT with the following file locations:

   test/multiverse/YOUR_PROJECT
   test/multiverse/YOUR_PROJECT/Envfile
   test/multiverse/YOUR_PROJECT/config/newrelic.yml
   test/multiverse/YOUR_PROJECT/FILE_WITH_A_TEST.rb

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3. Configure your Envfile. Use the Envfile to declare sets of gem dependencies for your Multiverse tests. For example, your Envfile might look like this:

   gemfile <-RB
     gem 'your-project', '~> 1.0.0'
     gem 'rack'
     gem 'newrelic_rpm'
     gem 'newrelic_your-project', path: '../../..'
   RB
   
   gemfile <-RB
     gem 'your-project', '~> 2.1.0'
     gem 'rack'
     gem 'newrelic_rpm'
     gem 'newrelic_your-project', path: '../../..'
   RB

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   Include the gem lines for newrelic_rpm and rack to ensure your Multiverse tests work.

4. Detect dependencies. If necessary, ensure your extension's instrumentation is loaded by running an additional dependency detection from your Multiverse tests:

   require 'newrelic/your-project'
   
   DependencyDetection.detect!
   
   class YourProjectTest > Minitest::Test
   end

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   To run your Multiverse tests against the gem dependencies in your Envfile:

• After setting up Multiverse for your gem, run rake test:multiverse to execute the tests in your directory.