[X-Pack Monitoring] Report pipeline protocol (#9516)

* Add getter for pipeline protocol

* Refactoring: extract bare string into constant

* Report pipeline protocol to Monitoring as part of logstash_state docs

* Report all protocols, not just first one

* Refactoring: rename constant to be more descriptive

* De-dupe protocols list before sending to monitoring

* Checking for single protocol

* Adding missing require

This was being masked and was uncovered when this test suite was run by itself

* Raising error if multiple protocols are specified

* Adding back comma

logstash-core/lib/logstash/config/pipeline_config.rb

@@ -5,14 +5,23 @@ module LogStash module Config
   class PipelineConfig
     include LogStash::Util::Loggable
 
-    attr_reader :source, :pipeline_id, :config_parts, :settings, :read_at
+    attr_reader :source, :pipeline_id, :config_parts, :protocol, :settings, :read_at
 
     def initialize(source, pipeline_id, config_parts, settings)
+      config_parts_array = config_parts.is_a?(Array) ? config_parts : [config_parts]
+      unique_protocols = config_parts_array
+        .map { |config_part| config_part.protocol.to_s }
+        .uniq
+
+      if unique_protocols.length > 1
+        raise(ArgumentError, "There should be exactly 1 unique protocol in config_parts. Found #{unique_protocols.length.to_s}.")
+      end
+        
       @source = source
       @pipeline_id = pipeline_id
       # We can't use Array() since config_parts may be a java object!
-      config_parts_array = config_parts.is_a?(Array) ? config_parts : [config_parts]
       @config_parts = config_parts_array.sort_by { |config_part| [config_part.protocol.to_s, config_part.id] }
+      @protocol = unique_protocols[0]
       @settings = settings
       @read_at = Time.now
     end

logstash-core/spec/logstash/config/pipeline_config_spec.rb

@@ -1,6 +1,7 @@
 # encoding: utf-8
 require "logstash/config/pipeline_config"
 require "logstash/config/source/local"
+require_relative "../../support/helpers"
 
 describe LogStash::Config::PipelineConfig do
   let(:source) { LogStash::Config::Source::Local }
@@ -13,7 +14,6 @@ describe LogStash::Config::PipelineConfig do
       org.logstash.common.SourceWithMetadata.new("file", "/tmp/4", 0, 0, "input { generator4 }"),
       org.logstash.common.SourceWithMetadata.new("file", "/tmp/5", 0, 0, "input { generator5 }"),
       org.logstash.common.SourceWithMetadata.new("file", "/tmp/6", 0, 0, "input { generator6 }"),
-      org.logstash.common.SourceWithMetadata.new("string", "config_string", 0, 0, "input { generator1 }"),
     ]
   end
 
@@ -72,4 +72,13 @@ describe LogStash::Config::PipelineConfig do
       end
     end
   end
+
+  it "returns the pipeline's protocol" do
+    expect(subject.protocol).to eq((ordered_config_parts.uniq { | config_part | config_part.protocol })[0].protocol)
+  end
+
+  it "raises an ArgumentError when multiple protocols are supplied" do
+    unordered_config_parts << org.logstash.common.SourceWithMetadata.new("string", "config_string", 0, 0, "input { generator0 }")
+    expect { described_class.new(source, pipeline_id, unordered_config_parts, settings) }.to raise_error ArgumentError, /.+Found 2\./
+  end
 end

x-pack/lib/config_management/elasticsearch_source.rb

@@ -32,6 +32,7 @@ module LogStash
         queue.max_bytes
         queue.checkpoint.writes
       )
+      CENTRALLY_MANAGED_PIPELINE_PROTOCOL = "x-pack-config-management"
 
       def initialize(settings)
         super(settings)
@@ -98,7 +99,7 @@ module LogStash
 
         raise RemoteConfigError, "Empty configuration for pipeline_id: #{pipeline_id}" if config_string.nil? || config_string.empty?
 
-        config_part = org.logstash.common.SourceWithMetadata.new("x-pack-config-management", pipeline_id.to_s, config_string)
+        config_part = org.logstash.common.SourceWithMetadata.new(CENTRALLY_MANAGED_PIPELINE_PROTOCOL, pipeline_id.to_s, config_string)
 
         # We don't support multiple pipelines, so use the global settings from the logstash.yml file
         settings = @settings.clone

x-pack/lib/monitoring/inputs/metrics/state_event_factory.rb

@@ -27,6 +27,7 @@ module LogStash; module Inputs; class Metrics;
         "id" => pipeline.pipeline_id,
         "hash" => pipeline.lir.unique_hash,
         "ephemeral_id" => pipeline.ephemeral_id,
+        "protocol" => pipeline.pipeline_config.protocol,
         "workers" =>  pipeline.settings.get("pipeline.workers"),
         "batch_size" =>  pipeline.settings.get("pipeline.batch.size"),
         "representation" => ::LogStash::Inputs::Metrics::StateEvent::LIRSerializer.serialize(pipeline.lir)