[Backport 7.x] Add Fingerprint ingest processor

src/Nest/Ingest/ProcessorFormatter.cs

@@ -46,7 +46,8 @@ internal class ProcessorFormatter : IJsonFormatter<IProcessor>
 			{ "circle", 30 },
 			{ "enrich", 31 },
 			{ "csv", 32 },
-			{ "uri_parts", 33 }
+			{ "uri_parts", 33 },
+			{ "fingerprint", 34 }
 		};
 
 		public IProcessor Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
@@ -169,6 +170,9 @@ public IProcessor Deserialize(ref JsonReader reader, IJsonFormatterResolver form
 					case 33:
 						processor = Deserialize<UriPartsProcessor>(ref reader, formatterResolver);
 						break;
+					case 34:
+						processor = Deserialize<FingerprintProcessor>(ref reader, formatterResolver);
+						break;
 				}
 			}
 			else
@@ -292,6 +296,9 @@ public void Serialize(ref JsonWriter writer, IProcessor value, IJsonFormatterRes
 				case "uri_parts":
 					Serialize<IUriPartsProcessor>(ref writer, value, formatterResolver);
 					break;
+				case "fingerprint":
+					Serialize<IFingerprintProcessor>(ref writer, value, formatterResolver);
+					break;
 				default:
 					var formatter = DynamicObjectResolver.ExcludeNullCamelCase.GetFormatter<IProcessor>();
 					formatter.Serialize(ref writer, value, formatterResolver);

src/Nest/Ingest/Processors/FingerprintProcessor.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Linq.Expressions;
+using System.Runtime.Serialization;
+using Elasticsearch.Net.Utf8Json;
+
+namespace Nest
+{
+	[InterfaceDataContract]
+	public interface IFingerprintProcessor : IProcessor
+	{
+		[DataMember(Name = "fields")]
+		Fields Fields { get; set; }
+
+		[DataMember(Name = "ignore_missing")]
+		bool? IgnoreMissing { get; set; }
+
+		[DataMember(Name = "method")]
+		string Method { get; set; }
+
+		[DataMember(Name = "salt")]
+		string Salt { get; set; }
+
+		[DataMember(Name = "target_field")]
+		Field TargetField { get; set; }
+	}
+
+	public class FingerprintProcessor : ProcessorBase, IFingerprintProcessor
+	{
+		protected override string Name => "fingerprint";
+
+		/// <inheritdoc />
+		public Fields Fields { get; set; }
+
+		/// <inheritdoc />
+		public bool? IgnoreMissing { get; set; }
+
+		/// <inheritdoc />
+		public string Method { get; set; }
+
+		/// <inheritdoc />
+		public string Salt { get; set; }
+
+		/// <inheritdoc />
+		public Field TargetField { get; set; }
+	}
+
+	/// <inheritdoc cref="IFingerprintProcessor" />
+	public class FingerprintProcessorDescriptor<T>
+		: ProcessorDescriptorBase<FingerprintProcessorDescriptor<T>, IFingerprintProcessor>, IFingerprintProcessor
+		where T : class
+	{
+		protected override string Name => "fingerprint";
+
+		Fields IFingerprintProcessor.Fields { get; set; }
+
+		string IFingerprintProcessor.Method { get; set; }
+
+		string IFingerprintProcessor.Salt { get; set; }
+
+		Field IFingerprintProcessor.TargetField { get; set; }
+
+		bool? IFingerprintProcessor.IgnoreMissing { get; set; }
+
+		/// <inheritdoc cref="IFingerprintProcessor.Fields" />
+		public FingerprintProcessorDescriptor<T> Fields(Fields fields) => Assign(fields, (a, v) => a.Fields = v);
+
+		/// <inheritdoc cref="IFingerprintProcessor.Fields" />
+		public FingerprintProcessorDescriptor<T> Fields(Func<FieldsDescriptor<T>, IPromise<Fields>> selector) =>
+			Assign(selector, (a, v) => a.Fields = v?.Invoke(new FieldsDescriptor<T>())?.Value);
+
+		/// <inheritdoc cref="IFingerprintProcessor.IgnoreMissing" />
+		public FingerprintProcessorDescriptor<T> IgnoreMissing(bool? ignoreMissing = true) => Assign(ignoreMissing, (a, v) => a.IgnoreMissing = v);
+
+		/// <inheritdoc cref="IFingerprintProcessor.Method" />
+		public FingerprintProcessorDescriptor<T> Method(string method) => Assign(method, (a, v) => a.Method = v);
+
+		/// <inheritdoc cref="IFingerprintProcessor.Salt" />
+		public FingerprintProcessorDescriptor<T> Salt(string salt) => Assign(salt, (a, v) => a.Salt = v);
+
+		/// <inheritdoc cref="IFingerprintProcessor.TargetField" />
+		public FingerprintProcessorDescriptor<T> TargetField(Field field) => Assign(field, (a, v) => a.TargetField = v);
+
+		/// <inheritdoc cref="IFingerprintProcessor.TargetField" />
+		public FingerprintProcessorDescriptor<T> TargetField<TValue>(Expression<Func<T, TValue>> objectPath) =>
+			Assign(objectPath, (a, v) => a.TargetField = v);
+	}
+}

src/Nest/Ingest/ProcessorsDescriptor.cs

@@ -181,5 +181,9 @@ public ProcessorsDescriptor Circle<T>(Func<CircleProcessorDescriptor<T>, ICircle
 		/// <inheritdoc cref="IUriPartsProcessor"/>
 		public ProcessorsDescriptor UriParts<T>(Func<UriPartsProcessorDescriptor<T>, IUriPartsProcessor> selector) where T : class =>
 			Assign(selector, (a, v) => a.AddIfNotNull(v?.Invoke(new UriPartsProcessorDescriptor<T>())));
+
+		/// <inheritdoc cref="IFingerprintProcessor"/>
+		public ProcessorsDescriptor Fingerprint<T>(Func<FingerprintProcessorDescriptor<T>, IFingerprintProcessor> selector) where T : class =>
+			Assign(selector, (a, v) => a.AddIfNotNull(v?.Invoke(new FingerprintProcessorDescriptor<T>())));
 	}
 }

tests/Tests/Ingest/ProcessorAssertions.cs

@@ -716,5 +716,21 @@ public class UriParts : ProcessorAssertion
 			public override object Json => new { field = "description", keep_original = true, remove_if_successful = true };
 			public override string Key => "uri_parts";
 		}
+
+		[SkipVersion("<7.12.0", "Uses fingerprint processor which was introduced in 7.12.0")]
+		public class Fingerprint : ProcessorAssertion
+		{
+			public override Func<ProcessorsDescriptor, IPromise<IList<IProcessor>>> Fluent => d => d
+				.Fingerprint<Project>(ud => ud
+					.Fields(p => p.Fields(f => f.Labels))
+					.Method("MD5")
+					.Salt("ThisIsASalt!")
+					.TargetField(p => p.Description)
+					.IgnoreMissing());
+
+			public override IProcessor Initializer => new FingerprintProcessor { Fields = "labels", Method = "MD5", Salt = "ThisIsASalt!", TargetField = "description", IgnoreMissing = true };
+			public override object Json => new { fields =  new[] { "labels" }, method = "MD5", salt = "ThisIsASalt!", target_field = "description", ignore_missing = true };
+			public override string Key => "fingerprint";
+		}
 	}
 }