[exporter/elasticsearch] Make OTel mapping mode send to data streams only (open-telemetry#35839)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Make OTel mapping mode use RequireDataStream in docappender, which means
it will only send to data streams. This prevents auto creating regular
indices in OTel mapping mode due to a race condition in Elasticsearch
where otel-data index templates are not ready.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue

<!--Describe what testing was performed and which tests were added.-->
#### Testing

<!--Describe the documentation added.-->
#### Documentation

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Author: carsonip

.chloggen/elasticsearchexporter_otel-mode-require-data-stream.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: elasticsearchexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Make OTel mapping mode send to data streams only
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35839]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: This prevents auto creating regular indices in OTel mapping mode due to a race condition in Elasticsearch where otel-data index templates are not ready.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

exporter/elasticsearchexporter/bulkindexer.go

@@ -73,6 +73,7 @@ func bulkIndexerConfig(client *elasticsearch.Client, config *Config) docappender
 		MaxDocumentRetries:    maxDocRetries,
 		Pipeline:              config.Pipeline,
 		RetryOnDocumentStatus: config.Retry.RetryOnStatus,
+		RequireDataStream:     config.MappingMode() == MappingOTel,
 	}
 }
 

exporter/elasticsearchexporter/bulkindexer_test.go

@@ -115,6 +115,61 @@ func TestAsyncBulkIndexer_flush(t *testing.T) {
 	}
 }
 
+func TestAsyncBulkIndexer_requireDataStream(t *testing.T) {
+	tests := []struct {
+		name                  string
+		config                Config
+		wantRequireDataStream bool
+	}{
+		{
+			name: "ecs",
+			config: Config{
+				NumWorkers: 1,
+				Mapping:    MappingsSettings{Mode: MappingECS.String()},
+			},
+			wantRequireDataStream: false,
+		},
+		{
+			name: "otel",
+			config: Config{
+				NumWorkers: 1,
+				Mapping:    MappingsSettings{Mode: MappingOTel.String()},
+			},
+			wantRequireDataStream: true,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			requireDataStreamCh := make(chan bool, 1)
+			client, err := elasticsearch.NewClient(elasticsearch.Config{Transport: &mockTransport{
+				RoundTripFunc: func(r *http.Request) (*http.Response, error) {
+					if r.URL.Path == "/_bulk" {
+						requireDataStreamCh <- r.URL.Query().Get("require_data_stream") == "true"
+					}
+					return &http.Response{
+						Header: http.Header{"X-Elastic-Product": []string{"Elasticsearch"}},
+						Body:   io.NopCloser(strings.NewReader(successResp)),
+					}, nil
+				},
+			}})
+			require.NoError(t, err)
+
+			bulkIndexer, err := newAsyncBulkIndexer(zap.NewNop(), client, &tt.config)
+			require.NoError(t, err)
+			session, err := bulkIndexer.StartSession(context.Background())
+			require.NoError(t, err)
+
+			assert.NoError(t, session.Add(context.Background(), "foo", strings.NewReader(`{"foo": "bar"}`), nil))
+			assert.NoError(t, bulkIndexer.Close(context.Background()))
+
+			assert.Equal(t, tt.wantRequireDataStream, <-requireDataStreamCh)
+		})
+	}
+}
+
 func TestAsyncBulkIndexer_flush_error(t *testing.T) {
 	tests := []struct {
 		name          string