Add support for pipeline to decode from metadata target_ingest_pipeline

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 11.13.0
+ - add technology preview support for allowing events to individually encode a default pipeline with `[@metadata][target_ingest_pipeline]` (as part of a technology preview, this feature may change without notice) [#1113](https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/1113)
+
 ## 11.12.4
  - Changed the `manage_template` default value to `false` when data streams is enabled [#1111](https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/1111)
    - Added the `manage_template => false` as a valid data stream option

docs/index.asciidoc

@@ -849,12 +849,11 @@ not also set this field. That will raise an error at startup
 ===== `pipeline`
 
   * Value type is <<string,string>>
-  * Default value is `nil`
+  * There is no default value.
 
 Set which ingest pipeline you wish to execute for an event. You can also use
-event dependent configuration here like `pipeline =>
-"%{[@metadata][pipeline]}"`. The pipeline parameter won't be set if the value
-resolves to empty string ("").
+event dependent configuration here like `pipeline => "%{[@metadata][pipeline]}"`.
+The pipeline parameter won't be set if the value resolves to empty string ("").
 
 [id="plugins-{type}s-{plugin}-pool_max"]
 ===== `pool_max`

lib/logstash/outputs/elasticsearch.rb

@@ -524,19 +524,22 @@ def common_event_params(event)
         routing_field_name => @routing ? event.sprintf(@routing) : nil
     }
 
-    if @pipeline
-      value = event.sprintf(@pipeline)
-      # convention: empty string equates to not using a pipeline
-      # this is useful when using a field reference in the pipeline setting, e.g.
-      #      elasticsearch {
-      #        pipeline => "%{[@metadata][pipeline]}"
-      #      }
-      params[:pipeline] = value unless value.empty?
-    end
+    target_pipeline = resolve_pipeline(event)
+    # convention: empty string equates to not using a pipeline
+    # this is useful when using a field reference in the pipeline setting, e.g.
+    #      elasticsearch {
+    #        pipeline => "%{[@metadata][pipeline]}"
+    #      }
+    params[:pipeline] = target_pipeline unless (target_pipeline.nil? || target_pipeline.empty?)
 
     params
   end
 
+  def resolve_pipeline(event)
+    pipeline_template = @pipeline || event.get("[@metadata][target_ingest_pipeline]")&.to_s
+    pipeline_template && event.sprintf(pipeline_template)
+  end
+
   @@plugins = Gem::Specification.find_all{|spec| spec.name =~ /logstash-output-elasticsearch-/ }
 
   @@plugins.each do |plugin|

logstash-output-elasticsearch.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name            = 'logstash-output-elasticsearch'
-  s.version         = '11.12.4'
+  s.version         = '11.13.0'
   s.licenses        = ['apache-2.0']
   s.summary         = "Stores logs in Elasticsearch"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"

spec/unit/outputs/elasticsearch_spec.rb

@@ -590,7 +590,7 @@
 
       let(:event) { LogStash::Event.new("pipeline" => "my-ingest-pipeline") }
 
-      it "should interpolate the pipeline value and set it" do
+      it "interpolate the pipeline value and set it" do
         expect(subject.send(:event_action_tuple, event)[1]).to include(:pipeline => "my-ingest-pipeline")
       end
     end
@@ -600,7 +600,66 @@
 
       let(:event) { LogStash::Event.new("pipeline" => "") }
 
-      it "should interpolate the pipeline value but not set it because it is empty" do
+      it "interpolates the pipeline value but not set it because it is empty" do
+        expect(subject.send(:event_action_tuple, event)[1]).not_to include(:pipeline)
+      end
+    end
+
+    context "with both pipeline and target_ingest_pipeline" do
+      let(:options) { {"pipeline" => "%{pipeline}" } }
+      let(:event) { LogStash::Event.new({"pipeline" => "my-ingest-pipeline", "[@metadata][target_ingest_pipeline]" => "meta-ingest-pipeline"}) }
+
+      it "interpolates the plugin's pipeline value" do
+        expect(subject.send(:event_action_tuple, event)[1]).to include(:pipeline => "my-ingest-pipeline")
+      end
+
+      context "when the plugin's `pipeline` is constant" do
+        let(:options) { super().merge("pipeline" => "my-constant-pipeline") }
+         it "uses plugin's pipeline value" do
+          expect(subject.send(:event_action_tuple, event)[1]).to include(:pipeline => "my-constant-pipeline")
+        end
+      end
+
+      context "when the plugin's `pipeline` includes an unresolvable sprintf placeholder" do
+        let(:options) { super().merge("pipeline" => "reference-%{unset}-field") }
+        it "does not use the target_ingest_pipeline" do
+          # when sprintf doesn't resolve a placeholder, the behaviour of our `pipeline` is UNSPECIFIED.
+          # here we only validate that the presence of the magic field does not
+          # override an explicitly-configured pipeline.
+          expect(subject.send(:event_action_tuple, event)[1]).to_not include(:pipeline => "my-ingest-pipeline")
+        end
+      end
+    end
+
+    context "with empty pipeline and target_ingest_pipeline" do
+      let(:options) { {"pipeline" => "%{pipeline}" } }
+      let(:event) { LogStash::Event.new({"pipeline" => "", "[@metadata][target_ingest_pipeline]" => "meta-ingest-pipeline"}) }
+
+      it "interpolates the pipeline value but not set it because pipeline is empty" do
+        expect(subject.send(:event_action_tuple, event)[1]).not_to include(:pipeline)
+      end
+    end
+
+    context "with target_ingest_pipeline" do
+      let(:event) { LogStash::Event.new({"pipeline" => "", "@metadata" => {"target_ingest_pipeline" => "meta-ingest-pipeline"}}) }
+
+      it "interpolates the target_ingest_pipeline value and set it" do
+        expect(subject.send(:event_action_tuple, event)[1]).to include(:pipeline => "meta-ingest-pipeline")
+      end
+    end
+
+    context "with empty target_ingest_pipeline" do
+      let(:event) { LogStash::Event.new({"pipeline" => "", "@metadata" => {"host" => "elastic"}}) }
+
+      it "does not set pipeline" do
+        expect(subject.send(:event_action_tuple, event)[1]).not_to include(:pipeline)
+      end
+    end
+
+    context "with empty pipeline and empty target_ingest_pipeline" do
+      let(:event) { LogStash::Event.new }
+
+      it "does not set pipeline" do
         expect(subject.send(:event_action_tuple, event)[1]).not_to include(:pipeline)
       end
     end