Module: Datadog::Lambda

Defined in:
lib/datadog/lambda.rb,
lib/datadog/lambda/version.rb

Overview

Instruments AWS Lambda functions with Datadog distributed tracing and custom metrics

Defined Under Namespace

Modules: VERSION

Class Method Summary collapse

Class Method Details

.configure_apm ⇒ Object

Configures Datadog’s APM tracer with lambda specific defaults. Same options can be given as Datadog.configure in tracer See github.com/DataDog/dd-trace-rb/blob/master/docs/GettingStarted.md#quickstart-for-ruby-applications



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# File 'lib/datadog/lambda.rb', line 32

def self.configure_apm
  require 'datadog/tracing'
  require 'datadog/tracing/transport/io'

  @patch_http = false
  # Needed to keep trace flushes on a single line
  $stdout.sync = true

  Datadog.configure do |c|
    unless Datadog::Utils.extension_running?
      c.tracing.writer = Datadog::Tracing::SyncWriter.new(
        transport: Datadog::Tracing::Transport::IO.default
      )
    end
    c.tags = { "_dd.origin": 'lambda' }
    # Enable AWS SDK instrumentation
    c.tracing.instrument :aws if trace_managed_services?

    yield(c) if block_given?
  end
end

.dd_lambda_layer_tag ⇒ Object 



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# File 'lib/datadog/lambda.rb', line 93

def self.dd_lambda_layer_tag
  RUBY_VERSION[0, 3].tr('.', '')
end

.do_enhanced_metrics? ⇒ boolean

Check the DD_ENHANCED_METRICS environment variable enhanced metrics

Returns:

  • (boolean) —

    true if this lambda should have



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# File 'lib/datadog/lambda.rb', line 162

def self.do_enhanced_metrics?
  dd_enhanced_metrics = ENV['DD_ENHANCED_METRICS']
  return true if dd_enhanced_metrics.nil?

  dd_enhanced_metrics.downcase == 'true'
end

.gen_enhanced_tags(context) ⇒ hash

Generate tags for enhanced metrics rubocop:disable Metrics/AbcSize, Metrics/MethodLength

Parameters:

Returns:

  • (hash) —

    a hash of the enhanced metrics tags



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# File 'lib/datadog/lambda.rb', line 101

def self.gen_enhanced_tags(context)
  arn_parts = context.invoked_function_arn.to_s.split(':')
  # Check if we have an alias or version
  function_alias = arn_parts[7].nil? ? nil : arn_parts[7]

  tags = {
    functionname: context.function_name,
    region: arn_parts[3],
    account_id: arn_parts[4],
    memorysize: context.memory_limit_in_mb,
    cold_start: @is_cold_start,
    runtime: "Ruby #{RUBY_VERSION}",
    resource: context.function_name,
    datadog_lambda: Datadog::Lambda::VERSION::STRING.to_sym
  }
  begin
    tags[:dd_trace] = Gem.loaded_specs['datadog'].version
  rescue StandardError
    Datadog::Utils.logger.debug 'datadog unavailable'
  end
  # If we have an alias...
  unless function_alias.nil?
    # If the alis version is $Latest, drop the $ for ddog tag convention.
    if function_alias.start_with?('$')
      function_alias[0] = ''
      # If the alias is not a version number add the executed version tag
    elsif !/\A\d+\z/.match(function_alias)
      tags[:executedversion] = context.function_version
    end
    # Append the alias to the resource tag
    tags[:resource] = "#{context.function_name}:#{function_alias}"
  end

  tags
rescue StandardError => e
  Datadog::Utils.logger.error 'Unable to parse Lambda context' \
  "#{context}: #{e}"
  {}
end

.initialize_listener ⇒ Object 



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# File 'lib/datadog/lambda.rb', line 178

def self.initialize_listener
  handler = ENV['_HANDLER'].nil? ? 'handler' : ENV['_HANDLER']
  function = ENV['AWS_LAMBDA_FUNCTION_NAME']
  merge_xray_traces = false
  merge_xray_traces_env = ENV['DD_MERGE_DATADOG_XRAY_TRACES']
  unless merge_xray_traces_env.nil?
    merge_xray_traces = merge_xray_traces_env.downcase == 'true'
    Datadog::Utils.logger.debug("Setting merge traces #{merge_xray_traces}")
  end

  # Only initialize listener if Tracing enabled.
  unless Datadog::Tracing.enabled?
    Datadog::Utils.logger.debug 'datadog unavailable'
    return nil
  end

  Trace::Listener.new(
    handler_name: handler,
    function_name: function,
    patch_http: @patch_http,
    merge_xray_traces:
  )
end

.metric(name, value, time: nil, **tags) ⇒ Object

Send a custom distribution metric

Parameters:

  • name (String) —

    name of the metric

  • value (Numeric) —

    value of the metric

  • time (Time) (defaults to: nil) —

    the time of the metric, should be in the past

  • tags (Hash) —

    hash of tags, must be in “my.tag.name”:“value” format



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# File 'lib/datadog/lambda.rb', line 86

def self.metric(name, value, time: nil, **tags)
  raise 'name must be a string' unless name.is_a?(String)
  raise 'value must be a number' unless value.is_a?(Numeric)

  @metrics_client.distribution(name, value, time:, **tags)
end

.record_enhanced(metric_name, context) ⇒ boolean

rubocop:enable Metrics/AbcSize, Metrics/MethodLength Format and add tags to enhanced metrics This method wraps the metric method, checking the DD_ENHANCED_METRICS environment variable, adding ‘aws.lambda.enhanced’ to the metric name, and adding the enhanced metric tags to the enhanced metrics.

Parameters:

  • metric_name (String) —

    basic name of the metric

  • context (Object) —

    AWS Ruby Lambda Context

Returns:

  • (boolean) —

    false if the metric was not added for some reason, true otherwise (for ease of testing



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# File 'lib/datadog/lambda.rb', line 151

def self.record_enhanced(metric_name, context)
  return false unless do_enhanced_metrics?

  etags = gen_enhanced_tags(context)
  metric("aws.lambda.enhanced.#{metric_name}", 1, **etags)
  true
end

.trace_context ⇒ Object

Gets the current tracing context



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# File 'lib/datadog/lambda.rb', line 77

def self.trace_context
  Hash[Datadog::Trace.trace_context]
end

.trace_managed_services? ⇒ boolean

Read DD_TRACE_MANAGED_SERVICES environment variable

Returns:

  • (boolean) —

    true if we should trace AWS services



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# File 'lib/datadog/lambda.rb', line 171

def self.trace_managed_services?
  dd_trace_managed_services = ENV[Trace::DD_TRACE_MANAGED_SERVICES]
  return true if dd_trace_managed_services.nil?

  dd_trace_managed_services.downcase == 'true'
end

.wrap(event, context, &block) ⇒ Object

Wrap the body of a lambda invocation

Parameters:

  • event (Object) —

    event sent to lambda

  • context (Object) —

    lambda context

  • block (Proc) —

    implementation of the handler function.



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# File 'lib/datadog/lambda.rb', line 58

def self.wrap(event, context, &block)
  @listener ||= initialize_listener
  record_enhanced('invocations', context)
  begin
    cold = @is_cold_start
    @listener&.on_start(event:, request_context: context, cold_start: cold)
    @response = block.call
  rescue StandardError => e
    record_enhanced('errors', context)
    raise e
  ensure
    @listener&.on_end(response: @response)
    @is_cold_start = false
    @metrics_client.close
  end
  @response
end