Automatically apply logs/metrics defaults based on DataStreamName.Type (

#15)

src/Elastic.Ingest.Elasticsearch/DataStreams/DataStreamChannel.cs

@@ -2,6 +2,8 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 
+using System.Collections.Generic;
+using System.Linq;
 using Elastic.Ingest.Elasticsearch.Serialization;
 using Elastic.Ingest.Transport;
 
@@ -28,10 +30,13 @@ public DataStreamChannel(DataStreamChannelOptions<TEvent> options) : base(option
 		/// <returns>A tuple of (name, body) describing the index template</returns>
 		protected override (string, string) GetDefaultIndexTemplate(string name, string match, string mappingsName, string settingsName)
 		{
+			var additionalComponents = GetInferredComponentTemplates();
+			var additionalComponentsJson = string.Join(", ", additionalComponents.Select(a => $"\"{a}\""));
+
 			var indexTemplateBody = @$"{{
                 ""index_patterns"": [""{match}""],
                 ""data_stream"": {{ }},
-                ""composed_of"": [ ""{mappingsName}"", ""{settingsName}"", ""data-streams-mappings"" ],
+                ""composed_of"": [ ""{mappingsName}"", ""{settingsName}"", {additionalComponentsJson} ],
                 ""priority"": 201,
                 ""_meta"": {{
                     ""description"": ""Template installed by .NET ingest libraries (https://github.com/elastic/elastic-ingest-dotnet)"",
@@ -40,5 +45,16 @@ protected override (string, string) GetDefaultIndexTemplate(string name, string
             }}";
 			return (name, indexTemplateBody);
 		}
+
+		protected List<string> GetInferredComponentTemplates()
+		{
+			var additionalComponents = new List<string> { "data-streams-mappings" };
+			// if we know the type of data is logs or metrics apply certain defaults that Elasticsearch ships with.
+			if (Options.DataStream.Type.ToLowerInvariant() == "logs")
+				additionalComponents.AddRange(new[] { "logs-settings", "logs-mappings" });
+			else if (Options.DataStream.Type.ToLowerInvariant() == "metrics")
+				additionalComponents.AddRange(new[] { "metrics-settings", "metrics-mappings" });
+			return additionalComponents;
+		}
 	}
 }