fluent-plugin-formatter-protobuf

Fluentd formatter plugin to format messages into Protobuf v3 encoded binary.

Installation

RubyGems

$ gem install fluent-plugin-formatter-protobuf

GitHub RubyGems Registry

$ gem install \
  fluent-plugin-formatter-protobuf \
  --version "<version>" \
  --source "https://rubygems.pkg.github.com/fluent-plugins-nursery"

Bundler (RubyGems)

Add following line to your Gemfile:

gem "fluent-plugin-formatter-protobuf", "<version>"

Bundler (GitHub RubyGems Registry),

source "https://rubygems.pkg.github.com/fluent-plugins-nursery" do
  gem "fluent-plugin-formatter-protobuf", "<version>"
end

And then execute:

$ bundle

Quick start

Generate the protobuf ruby methods
1. e.g protoc --proto_path=. --ruby_out=. ./log.proto
Modify the <format> section to include class_name, which is your Protobuf message name, and include_paths, the path where the generated Ruby types are stored
1. Given protobuf class Your::Protobuf::Class::Name class should be given as Your.Protobuf.Class.Name in class_name. The exact name can be found in the generated Ruby files

Note

This plugin only supports Protobuf v3.

Example

<source>
    @type tcp
    tag tcp.events
    port 5170
    delimiter "\n"
    <parse>
        @type json
    </parse>
</source>

<match tcp.events>
    @type kafka2
    
    brokers "#{BROKER_ENDPOINTS}"
    compression_codec lz4

    <buffer topic>
        @type memory
        flush_interval 5s
    </buffer>

    <format>
        @type protobuf
        class_name "Log"
        include_paths ["/opt/fluent-plugin-formatter-protobuf/log_pb.rb"]
    </format>
</match>

Configuration

parameter	type	description	default
class_name	string (required)	Ruby Protobuf class name. Used to encode into Protobuf binary
decode_json	boolean (optional)	Serializes record from canonical proto3 JSON mapping (https://developers.google.com/protocol-buffers/docs/proto3#json) into binary	`false`
ignore_unknown_fields	boolean (optional)	Ignore unknown fields when decoding JSON. This parameter is only used if `decode_json` is `true`	`true`
format_field	string (optional)	When defined, the plugin will only serialise the record in the given field rather than the whole record. This is potentially useful if you intend to use this formatter with the Kafka output plugin (https://github.com/fluent/fluent-plugin-kafka#output-plugin) for example, where your record contains a field to determine which Kafka topic to write to, or the Kafka headers to include, but you do not wish to include those data in the resulting proto3 binary. Defaults to serialising the entire record.	`''`
include_paths	array (required)	Generated Ruby Protobuf class files path	`[]`
require_method	string (optional)	Determine how to bring the generated Ruby Protobuf class files into scope. If your generated Ruby Protobuf class files are provided by a Ruby Gem, you may want to use 'require'. If you are providing the generated files as files, you may want to use 'require_relative'	`require`

Tips

1. I have multiple `_pb.rb` files and they depend on one another. When I use this plugin, I'm getting a `LoadError`.

This happens because the plugin currently loads paths in include_paths sequentially. You can either sort the files in correct dependency order (which is cumbersome), or add to Ruby's $LOAD_PATH.

For example, you have 2 generated ruby files, a_pb.rb and b_pb.rb, and both a_pb.rb depends on b_pb.rb.

You can either order them in appropriate dependency order, such as

<format>
  @type protobuf
  class_name "SomePackage.A"
  include_paths ["/some/path/b_pb.rb", "/some/path/a_pb.rb"]
</format>

or you can put the generated files in a directory say /some/path/, and add to Ruby's $LOAD_PATH via the RUBYLIB environment variable.

e.g.

<format>
  @type protobuf
  class_name "SomePackage.A"
  include_paths ["/some/path/a_pb.rb"]
</format>

export RUBYLIB="${RUBYLIB}:/some/path/"
fluentd \
  --gemfile "/some/other/path/Gemfile" \
  --config "/some/other/path/fluent.conf"

License

Apache License, Version 2.0