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Elastic Docs ›Logstash Reference [7.3] ›Codec plugins

Protobuf codec plugin

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Protobuf codec plugin

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  • Plugin version: v1.2.1
  • Released on: 2019-05-28
  • Changelog

For other versions, see the Versioned plugin docs.

Installation

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For plugins not bundled by default, it is easy to install by running bin/logstash-plugin install logstash-codec-protobuf. See Working with plugins for more details.

Getting Help

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For questions about the plugin, open a topic in the Discuss forums. For bugs or feature requests, open an issue in Github. For the list of Elastic supported plugins, please consult the Elastic Support Matrix.

Description

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This codec converts protobuf encoded messages into logstash events and vice versa. It supports the protobuf versions 2 and 3.

The plugin requires the protobuf definitions to be compiled to ruby files.
For protobuf 2 use the ruby-protoc compiler.
For protobuf 3 use the official google protobuf compiler.

The following shows a usage example (protobuf v2) for decoding events from a kafka stream:

kafka
{
 topic_id => "..."
 key_deserializer_class => "org.apache.kafka.common.serialization.ByteArrayDeserializer"
 value_deserializer_class => "org.apache.kafka.common.serialization.ByteArrayDeserializer"
 codec => protobuf
 {
   class_name => "Animals::Mammals::Unicorn"
   include_path => ['/path/to/protobuf/definitions/UnicornProtobuf.pb.rb']
 }
}

Usage example for protobuf v3:

kafka
{
  topic_id => "..."
  key_deserializer_class => "org.apache.kafka.common.serialization.ByteArrayDeserializer"
  value_deserializer_class => "org.apache.kafka.common.serialization.ByteArrayDeserializer"
  codec => protobuf
  {
    class_name => "Animals.Mammals.Unicorn"
    include_path => ['/path/to/pb_definitions/Animal_pb.rb', '/path/to/pb_definitions/Unicorn_pb.rb']
    protobuf_version => 3
  }
}

The codec can be used in input and output plugins.
When using the codec in the kafka input plugin please set the deserializer classes as shown above.
When using the codec in an output plugin:

  • make sure to include all the desired fields in the protobuf definition, including timestamp. Remove fields that are not part of the protobuf definition from the event by using the mutate filter.
  • the @ symbol is currently not supported in field names when loading the protobuf definitions for encoding. Make sure to call the timestamp field timestamp instead of @timestamp in the protobuf file. Logstash event fields will be stripped of the leading @ before conversion.

Protobuf Codec Configuration Options

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Setting Input type Required

class_name

string

Yes

include_path

array

Yes

protobuf_version

number

Yes

 

class_name

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  • This is a required setting.
  • Value type is string
  • There is no default value for this setting.

Fully qualified name of the class to decode. Please note that the module delimiter is different depending on the protobuf version. For protobuf v2, use double colons:

class_name => "Animals::Mammals::Unicorn"

For protobuf v3, use single dots:

class_name => "Animals.Mammals.Unicorn"

For protobuf v3, you can copy the class name from the Descriptorpool registrations at the bottom of the generated protobuf ruby file. It contains lines like this:

Animals.Mammals.Unicorn = Google::Protobuf::DescriptorPool.generated_pool.lookup("Animals.Mammals.Unicorn").msgclass

If your class references other definitions: you only have to add the name of the main class here.

include_path

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  • This is a required setting.
  • Value type is array
  • There is no default value for this setting.

List of absolute pathes to files with protobuf definitions. When using more than one file, make sure to arrange the files in reverse order of dependency so that each class is loaded before it is refered to by another.

Example: a class Unicorn referencing another protobuf class Wings

module Animal
  module Mammal
    class Unicorn
      set_fully_qualified_name "Animal.Mammal.Unicorn"
      optional ::Bodypart::Wings, :wings, 1
      optional :string, :name, 2
      ...

would be configured as

include_path => ['/path/to/pb_definitions/wings.pb.rb','/path/to/pb_definitions/unicorn.pb.rb']

Please note that protobuf v2 files have the ending .pb.rb whereas files compiled for protobuf v3 end in _pb.rb.

protobuf_version

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  • Value type is number
  • Default value is 2

Protocol buffers version. Valid settings are 2, 3.

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