[Backport 2.x] Add fingerprint ingest processor

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased 2.x]
 ### Added
+- Add fingerprint ingest processor ([#13724](https://github.com/opensearch-project/OpenSearch/pull/13724))
 
 ### Dependencies
 - Update to Apache Lucene 9.11.0 ([#14042](https://github.com/opensearch-project/OpenSearch/pull/14042))

modules/ingest-common/src/main/java/org/opensearch/ingest/common/FingerprintProcessor.java

@@ -0,0 +1,279 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.ingest.common;
+
+import org.opensearch.common.Nullable;
+import org.opensearch.common.hash.MessageDigests;
+import org.opensearch.core.common.Strings;
+import org.opensearch.ingest.AbstractProcessor;
+import org.opensearch.ingest.ConfigurationUtils;
+import org.opensearch.ingest.IngestDocument;
+import org.opensearch.ingest.Processor;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.util.Base64;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.opensearch.ingest.ConfigurationUtils.newConfigurationException;
+
+/**
+ * Processor that generating hash value for the specified fields or fields not in the specified excluded list
+ */
+public final class FingerprintProcessor extends AbstractProcessor {
+    public static final String TYPE = "fingerprint";
+    // this processor is introduced in 2.16.0, we append the OpenSearch version to the hash method name to ensure
+    // that this processor always generates same hash value based on a specific hash method, if the processing logic
+    // of this processor changes in future version, the version number in the hash method should be increased correspondingly.
+    private static final Set<String> HASH_METHODS = Set.of("[email protected]", "[email protected]", "[email protected]", "[email protected]");
+
+    // fields used to generate hash value
+    private final List<String> fields;
+    // all fields other than the excluded fields are used to generate hash value
+    private final List<String> excludeFields;
+    // the target field to store the hash value, defaults to fingerprint
+    private final String targetField;
+    // hash method used to generate the hash value, defaults to SHA-1
+    private final String hashMethod;
+    private final boolean ignoreMissing;
+
+    FingerprintProcessor(
+        String tag,
+        String description,
+        @Nullable List<String> fields,
+        @Nullable List<String> excludeFields,
+        String targetField,
+        String hashMethod,
+        boolean ignoreMissing
+    ) {
+        super(tag, description);
+        if (fields != null && !fields.isEmpty()) {
+            if (fields.stream().anyMatch(Strings::isNullOrEmpty)) {
+                throw new IllegalArgumentException("field name in [fields] cannot be null nor empty");
+            }
+            if (excludeFields != null && !excludeFields.isEmpty()) {
+                throw new IllegalArgumentException("either fields or exclude_fields can be set");
+            }
+        }
+        if (excludeFields != null && !excludeFields.isEmpty() && excludeFields.stream().anyMatch(Strings::isNullOrEmpty)) {
+            throw new IllegalArgumentException("field name in [exclude_fields] cannot be null nor empty");
+        }
+
+        if (!HASH_METHODS.contains(hashMethod.toUpperCase(Locale.ROOT))) {
+            throw new IllegalArgumentException("hash method must be [email protected], [email protected] or [email protected] or [email protected]");
+        }
+        this.fields = fields;
+        this.excludeFields = excludeFields;
+        this.targetField = targetField;
+        this.hashMethod = hashMethod;
+        this.ignoreMissing = ignoreMissing;
+    }
+
+    public List<String> getFields() {
+        return fields;
+    }
+
+    public List<String> getExcludeFields() {
+        return excludeFields;
+    }
+
+    public String getTargetField() {
+        return targetField;
+    }
+
+    public String getHashMethod() {
+        return hashMethod;
+    }
+
+    public boolean isIgnoreMissing() {
+        return ignoreMissing;
+    }
+
+    @Override
+    public IngestDocument execute(IngestDocument document) {
+        // we should deduplicate and sort the field names to make sure we can get consistent hash value
+        final List<String> sortedFields;
+        Set<String> existingFields = new HashSet<>(document.getSourceAndMetadata().keySet());
+        Set<String> metadataFields = document.getMetadata()
+            .keySet()
+            .stream()
+            .map(IngestDocument.Metadata::getFieldName)
+            .collect(Collectors.toSet());
+        // metadata fields such as _index, _id and _routing are ignored
+        if (fields != null && !fields.isEmpty()) {
+            sortedFields = fields.stream()
+                .distinct()
+                .filter(field -> !metadataFields.contains(field))
+                .sorted()
+                .collect(Collectors.toList());
+        } else if (excludeFields != null && !excludeFields.isEmpty()) {
+            sortedFields = existingFields.stream()
+                .filter(field -> !metadataFields.contains(field) && !excludeFields.contains(field))
+                .sorted()
+                .collect(Collectors.toList());
+        } else {
+            sortedFields = existingFields.stream().filter(field -> !metadataFields.contains(field)).sorted().collect(Collectors.toList());
+        }
+        assert (!sortedFields.isEmpty());
+
+        final StringBuilder concatenatedFields = new StringBuilder();
+        sortedFields.forEach(field -> {
+            if (!document.hasField(field)) {
+                if (ignoreMissing) {
+                    return;
+                } else {
+                    throw new IllegalArgumentException("field [" + field + "] doesn't exist");
+                }
+            }
+
+            final Object value = document.getFieldValue(field, Object.class);
+            if (value instanceof Map) {
+                @SuppressWarnings("unchecked")
+                Map<String, Object> flattenedMap = toFlattenedMap((Map<String, Object>) value);
+                flattenedMap.entrySet().stream().sorted(Map.Entry.comparingByKey()).forEach(entry -> {
+                    String fieldValue = String.valueOf(entry.getValue());
+                    concatenatedFields.append("|")
+                        .append(field)
+                        .append(".")
+                        .append(entry.getKey())
+                        .append("|")
+                        .append(fieldValue.length())
+                        .append(":")
+                        .append(fieldValue);
+                });
+            } else {
+                String fieldValue = String.valueOf(value);
+                concatenatedFields.append("|").append(field).append("|").append(fieldValue.length()).append(":").append(fieldValue);
+            }
+        });
+        // if all specified fields don't exist and ignore_missing is true, then do nothing
+        if (concatenatedFields.length() == 0) {
+            return document;
+        }
+        concatenatedFields.append("|");
+
+        MessageDigest messageDigest = HashMethod.fromMethodName(hashMethod);
+        assert (messageDigest != null);
+        messageDigest.update(concatenatedFields.toString().getBytes(StandardCharsets.UTF_8));
+        document.setFieldValue(targetField, hashMethod + ":" + Base64.getEncoder().encodeToString(messageDigest.digest()));
+
+        return document;
+    }
+
+    @Override
+    public String getType() {
+        return TYPE;
+    }
+
+    /**
+     * Convert a map containing nested fields to a flattened map,
+     * for example, if the original map is
+     * {
+     *     "a": {
+     *         "b": 1,
+     *         "c": 2
+     *     }
+     * }, then the converted map is
+     * {
+     *     "a.b": 1,
+     *     "a.c": 2
+     * }
+     * @param map the original map which may contain nested fields
+     * @return a flattened map which has only one level fields
+     */
+    @SuppressWarnings("unchecked")
+    private Map<String, Object> toFlattenedMap(Map<String, Object> map) {
+        Map<String, Object> flattenedMap = new HashMap<>();
+        for (Map.Entry<String, Object> entry : map.entrySet()) {
+            if (entry.getValue() instanceof Map) {
+                toFlattenedMap((Map<String, Object>) entry.getValue()).forEach(
+                    (key, value) -> flattenedMap.put(entry.getKey() + "." + key, value)
+                );
+            } else {
+                flattenedMap.put(entry.getKey(), entry.getValue());
+            }
+        }
+        return flattenedMap;
+    }
+
+    /**
+     * The supported hash methods used to generate hash value
+     */
+    enum HashMethod {
+        MD5(MessageDigests.md5()),
+        SHA1(MessageDigests.sha1()),
+        SHA256(MessageDigests.sha256()),
+        SHA3256(MessageDigests.sha3256());
+
+        private final MessageDigest messageDigest;
+
+        HashMethod(MessageDigest messageDigest) {
+            this.messageDigest = messageDigest;
+        }
+
+        public static MessageDigest fromMethodName(String methodName) {
+            String name = methodName.toUpperCase(Locale.ROOT);
+            switch (name) {
+                case "[email protected]":
+                    return MD5.messageDigest;
+                case "[email protected]":
+                    return SHA1.messageDigest;
+                case "[email protected]":
+                    return SHA256.messageDigest;
+                case "[email protected]":
+                    return SHA3256.messageDigest;
+                default:
+                    return null;
+            }
+        }
+    }
+
+    public static final class Factory implements Processor.Factory {
+        @Override
+        public FingerprintProcessor create(
+            Map<String, Processor.Factory> registry,
+            String processorTag,
+            String description,
+            Map<String, Object> config
+        ) throws Exception {
+            List<String> fields = ConfigurationUtils.readOptionalList(TYPE, processorTag, config, "fields");
+            List<String> excludeFields = ConfigurationUtils.readOptionalList(TYPE, processorTag, config, "exclude_fields");
+            if (fields != null && !fields.isEmpty()) {
+                if (fields.stream().anyMatch(Strings::isNullOrEmpty)) {
+                    throw newConfigurationException(TYPE, processorTag, "fields", "field name cannot be null nor empty");
+                }
+                if (excludeFields != null && !excludeFields.isEmpty()) {
+                    throw newConfigurationException(TYPE, processorTag, "fields", "either fields or exclude_fields can be set");
+                }
+            }
+            if (excludeFields != null && !excludeFields.isEmpty() && excludeFields.stream().anyMatch(Strings::isNullOrEmpty)) {
+                throw newConfigurationException(TYPE, processorTag, "exclude_fields", "field name cannot be null nor empty");
+            }
+
+            String targetField = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "target_field", "fingerprint");
+            String hashMethod = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "hash_method", "[email protected]");
+            if (!HASH_METHODS.contains(hashMethod.toUpperCase(Locale.ROOT))) {
+                throw newConfigurationException(
+                    TYPE,
+                    processorTag,
+                    "hash_method",
+                    "hash method must be [email protected], [email protected], [email protected] or [email protected]"
+                );
+            }
+            boolean ignoreMissing = ConfigurationUtils.readBooleanProperty(TYPE, processorTag, config, "ignore_missing", false);
+            return new FingerprintProcessor(processorTag, description, fields, excludeFields, targetField, hashMethod, ignoreMissing);
+        }
+    }
+}

modules/ingest-common/src/main/java/org/opensearch/ingest/common/IngestCommonPlugin.java

@@ -109,6 +109,7 @@ public Map<String, Processor.Factory> getProcessors(Processor.Parameters paramet
         processors.put(CopyProcessor.TYPE, new CopyProcessor.Factory(parameters.scriptService));
         processors.put(RemoveByPatternProcessor.TYPE, new RemoveByPatternProcessor.Factory());
         processors.put(CommunityIdProcessor.TYPE, new CommunityIdProcessor.Factory());
+        processors.put(FingerprintProcessor.TYPE, new FingerprintProcessor.Factory());
         return Collections.unmodifiableMap(processors);
     }