plugin.rb

# frozen_string_literal: true
require "delayed_job"

module Sentry
  module DelayedJob
    class Plugin < ::Delayed::Plugin
      # need to symbolize strings as keyword arguments in Ruby 2.4~2.6
      DELAYED_JOB_CONTEXT_KEY = :"Delayed-Job"
      ACTIVE_JOB_CONTEXT_KEY = :"Active-Job"
      OP_NAME = "queue.delayed_job".freeze

      callbacks do |lifecycle|
        lifecycle.before(:enqueue) do |job, *args, &block|
          inject_trace_data(job) if Sentry.initialized?
        end

        lifecycle.around(:invoke_job) do |job, *args, &block|
          env = extract_trace_data(job)
          next block.call(job, *args) unless Sentry.initialized?

          Sentry.with_scope do |scope|
            contexts = generate_contexts(job)
            name = contexts.dig(ACTIVE_JOB_CONTEXT_KEY, :job_class) || contexts.dig(DELAYED_JOB_CONTEXT_KEY, :job_class)
            scope.set_transaction_name(name, source: :task)
            scope.set_contexts(**contexts)
            scope.set_tags("delayed_job.queue" => job.queue, "delayed_job.id" => job.id.to_s)

            transaction = start_transaction(scope, env, contexts)
            scope.set_span(transaction) if transaction

            begin
              block.call(job, *args)

              finish_transaction(transaction, 200)
            rescue Exception => e
              capture_exception(e, job)
              finish_transaction(transaction, 500)
              raise
            end
          end
        end
      end

      def self.generate_contexts(job)
        context = {}

        context[DELAYED_JOB_CONTEXT_KEY] = {
          id: job.id.to_s,
          priority: job.priority,
          attempts: job.attempts,
          run_at: job.run_at,
          locked_at: job.locked_at,
          locked_by: job.locked_by,
          queue: job.queue,
          created_at: job.created_at,
          last_error: job.last_error&.byteslice(0..1000),
          handler: job.handler&.byteslice(0..1000),
          job_class: compute_job_class(job.payload_object),
        }

        if job.payload_object.respond_to?(:job_data)
          context[ACTIVE_JOB_CONTEXT_KEY] = {}

          job.payload_object.job_data.each do |key, value|
            context[ACTIVE_JOB_CONTEXT_KEY][key.to_sym] = value
          end
        end

        context
      end

      def self.compute_job_class(payload_object)
        if payload_object.is_a?(Delayed::PerformableMethod)
          klass = payload_object.object.is_a?(Class) ? payload_object.object.name : payload_object.object.class.name
          "#{klass}##{payload_object.method_name}"
        else
          payload_object.class.name
        end
      end

      def self.capture_exception(exception, job)
        Sentry::DelayedJob.capture_exception(exception, hint: { background: false }) if report?(job)
      end

      def self.report?(job)
        return true unless Sentry.configuration.delayed_job.report_after_job_retries

        # We use the predecessor because the job's attempts haven't been increased to the new
        # count at this point.
        max_attempts = job&.max_attempts&.pred || Delayed::Worker.max_attempts.pred
        job.attempts >= max_attempts
      end

      def self.start_transaction(scope, env, contexts)
        options = { name: scope.transaction_name, source: scope.transaction_source, op: OP_NAME }
        transaction = Sentry.continue_trace(env, **options)
        Sentry.start_transaction(transaction: transaction, custom_sampling_context: contexts, **options)
      end

      def self.finish_transaction(transaction, status)
        return unless transaction

        transaction.set_http_status(status)
        transaction.finish
      end

      def self.inject_trace_data(job)
        # active job style is handled in the sentry-rails/active_job extension more generally
        # if someone enqueues manually with some other job class, we cannot make assumptions unfortunately
        payload_object = job.payload_object
        return unless payload_object.is_a?(Delayed::PerformableMethod)

        # we will add the trace data to args and remove it again
        # this is hacky but it's the only reliable way to survive the YAML serialization/deserialization
        payload_object.args << { sentry: Sentry.get_trace_propagation_headers }
        job.payload_object = payload_object
      end

      def self.extract_trace_data(job)
        payload_object = job.payload_object
        return nil unless payload_object.is_a?(Delayed::PerformableMethod)

        ind = payload_object.args.index { |a| a.is_a?(Hash) && a.key?(:sentry) }
        return nil unless ind

        env = payload_object.args[ind][:sentry]
        payload_object.args.delete_at(ind)
        env
      end
    end
  end
end

Delayed::Worker.plugins << Sentry::DelayedJob::Plugin