lib/elastic_apm/grpc.rb

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# license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright
# ownership. Elasticsearch B.V. licenses this file to you under
# the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

# frozen_string_literal: true

module ElasticAPM
  # @api private
  class GRPC
    # @api private
    class ClientInterceptor < ::GRPC::ClientInterceptor
      TYPE = 'external'
      SUBTYPE = 'grpc'

      # rubocop:disable Lint/UnusedMethodArgument, Style/ExplicitBlockArgument
      def request_response(request:, call:, method:, metadata:)
        return yield unless (transaction = ElasticAPM.current_transaction)
        if (trace_context = transaction.trace_context)
          trace_context.apply_headers { |k, v| metadata[k.downcase] = v }
        end

        ElasticAPM.with_span(
          method, TYPE,
          subtype: SUBTYPE,
          context: span_context(call)
        ) do
          yield
        end
      end
      # rubocop:enable Lint/UnusedMethodArgument, Style/ExplicitBlockArgument

      private

      def span_context(call)
        peer = call.instance_variable_get(:@wrapped)&.peer
        return unless peer

        split_peer = URI.split(peer)
        destination = ElasticAPM::Span::Context::Destination.new(
          address: split_peer[0],
          port: split_peer[6],
          service: { type: TYPE, name: SUBTYPE, resource: peer }
        )
        ElasticAPM::Span::Context.new(destination: destination)
      end
    end

    # @api private
    class ServerInterceptor < ::GRPC::ClientInterceptor
      TYPE = 'request'

      # rubocop:disable Lint/UnusedMethodArgument
      def request_response(request:, call:, method:)
        transaction = start_transaction(call)
        yield
        transaction.done 'success'
      rescue ::Exception => e
        ElasticAPM.report(e, handled: false)
        transaction&.done 'error'
        raise
      ensure
        ElasticAPM.end_transaction
      end
      # rubocop:enable Lint/UnusedMethodArgument

      private

      def start_transaction(call)
        ElasticAPM.start_transaction(
          'grpc',
          'request',
          trace_context: trace_context(call)
        )
      end

      def trace_context(call)
        TraceContext.parse(metadata: call.metadata)
      rescue TraceContext::InvalidTraceparentHeader
        warn "Couldn't parse invalid trace context header: #{call.metadata}"
        nil
      end
    end
  end
end