Logging

Enabling gRPC Logging

To enable logging for this library, set the logger for the underlying gRPC library. The logger that you set may be a Ruby stdlib Logger as shown below, or a Google::Cloud::Logging::Logger that will write logs to Stackdriver Logging. See grpc/logconfig.rb and the gRPC spec_helper.rb for additional information.

Configuring a Ruby stdlib logger:

require "logger"
require "grpc"

module MyLogger
  LOGGER = Logger.new $stderr, level: Logger::WARN
  def logger
    LOGGER
  end
end

# Define a gRPC module-level logger method before grpc/logconfig.rb loads.
module GRPC
  extend MyLogger
end

Adding gRPC interceptors

gRPC accepts Ruby-language interceptors that allow you to insert your own custom logging into a client's RPC calls. (gRPC interceptors are also useful for auth, metrics, tracing and similar use cases.)

This library performs RPCs using the following gapic clients from the underlying google-cloud-pubsub-v1 library:

To add a gRPC interceptor to one or more of these clients, first implement your logic as a subclass of GRPC::ClientInterceptor. The example below logs all four types of gRPC calls (unary, client streaming, server streaming, and bi-directional streaming.) It also demonstrates how to set a metadata field.

require "grpc"
require "logger"
require "securerandom"

class MyInterceptor < GRPC::ClientInterceptor
  attr_reader :name

  def initialize name
    @name = name
  end

  def request_response(request:, call:, method:, metadata:)
    logger.info "[#{name}] Sending unary request/response to #{method}"
    metadata["request_id"] = generate_request_id
    yield
  end

  def client_streamer(requests:, call:, method:, metadata:)
    logger.info "[#{name}] Sending client streamer to #{method}"
    metadata["request_id"] = generate_request_id
    yield
  end

  def server_streamer(request:, call:, method:, metadata:)
    logger.info "[#{name}] Sending server streamer to #{method}"
    metadata["request_id"] = generate_request_id
    yield
  end

  def bidi_streamer(requests:, call:, method:, metadata:)
    logger.info "[#{name}] Sending bidi streamer to #{method}"
    metadata["request_id"] = generate_request_id
    yield
  end

  private

  def logger
    @logger ||= Logger.new(STDOUT)
  end

  def generate_request_id
    SecureRandom.uuid
  end
end

Next, use the block yielded by a Client.configure method to add an instance of your class to the interceptors configuration of one or more of the generated clients listed above.

Note that the Google::Cloud::PubSub::V1 configurations must be performed before the Google::Cloud::PubSub client is instantiated.

require "google/cloud/pubsub"

Google::Cloud::PubSub::V1::Publisher::Client.configure do |config|
  config.interceptors = [MyInterceptor.new("MyPublisherInterceptor")]
end

Google::Cloud::PubSub::V1::Subscriber::Client.configure do |config|
  config.interceptors = [MyInterceptor.new("MySubscriberInterceptor")]
end

pubsub = Google::Cloud::PubSub.new