Rabbitmq output plugin : dynamic values on headers not working

[MarineW29]

I would like to set dynamic values to headers in properties of the message published in RabbitMQ, but the field are not replaces with their values.

I saw the feature has been added in 7.1.0 version on RabbitMQ integration plugin : #27 (comment) but it doesn't seem to work.

According to this discussion, it seems that the code sprintf the top-level items in message_properties (such as app_id) but does not iterate over the items nested inside them.

Version of the plugin I use :

    bash-4.2$ logstash-plugin list --verbose
    (...)
    logstash-integration-rabbitmq (7.1.1)
     ├── logstash-input-rabbitmq
     └── logstash-output-rabbitmq

My configuration :

    output {
      rabbitmq {
        id => "mwx-rabbitmq-output"
        host =>"rabbitmq"
        port => "5672"
        user => "***"
        password => "***"
        ssl => "false"
        vhost => "/"
        durable => true 
        automatic_recovery => true
        persistent => true
        exchange => "sys-logstash-out"
        exchange_type => "topic"
        key => "app-%{[properties][app-id]}-default"
        # Fill the payload with "message" field :
        codec => plain { format => "%{[message]}" }
        message_properties => {
          "content_type" => "application/json"
          "priority" => 2
          "app_id" => "%{[properties][app-id]}"
          "headers" => {
            "test" => "%{[message]}"
          }
        }
      }
    }

The resulting message in RabbitMQ :

    Exchange          sys-logstash-out
    Routing Key	      app-app-test-MWX-default
    Redelivered       ●
    Properties	
       app_id:        app-test-MWX
       priority:      2
       delivery_mode: 2
       headers:	
          test:       %{[message]}
       content_type:  application/json
    Payload           Test header 1

As you can see :

• "%{[message]}" exists and is well replaced in payload part.
• the "app_id" property is also OK
• but the "test" header is not OK

Thanks.

[DIFRIN]

logstash-integration-rabbitmq/lib/logstash/outputs/rabbitmq.rb

Line 146 in 1d8117c

constant_properties = template.reject { |_,v| templated?(v) }

With this headers attributs of message_properties will fall all time in the constant_properties because it's not of type string

A Solution could be to extract constant_properties[:headers] then do the same as the variable_properties and reseting it in constant_properties before freezing. Something like

`def buildHeaders(event)

      if @constant_properties[:headers]

        constant_headers = @constant_properties[:headers].reject { |_, v| templated?(v) }
        variable_headers = @constant_properties[:headers].select { |_, v| templated?(v) }

        headers = variable_headers.each_with_object(constant_headers.dup) do |(k, v), memo|
          memo.store(k, event.sprintf(v))
        end

        @constant_properties[:headers] = headers
        @constant_properties.freez
      end
    end`

@yaauie can you help us fix this issue ? Thank you in advance