Setting the file. One moment.
Chapter 45 · Amazon Opensearch Service
Subchapter 45.40
references/source-elasticsearch.mdMarkdown7 KBView on GitHub
Stable-core facts about Elasticsearch as a migration source to Amazon OpenSearch Service. Version-volatile details (exact OpenSearch minor that reaches parity, current MA version support floor/ceiling) MUST be tagged and resolved against live docs in Step 8 of the workflow.
[verify]Use this to populate §1 “Recommended path” and §8 “Migration Plan” in the report.
| ES version family | Fork status | Snapshot/Restore into AOS | Primary HDM strategy | Notes |
|---|---|---|---|---|
| ES 1.x / 2.x / 5.x | Pre-fork | NOT recommended (multi-major hop) | Migration Assistant Historical Data Migration | MA HDM supports source ES back to 1.0; multi-major hops require MA |
| ES 6.x | Pre-fork | Supported (pre-fork) | Snapshot/Restore OR MA HDM | Snapshot/Restore is the simpler path; MA HDM preferred for large/complex |
| ES ≤ 7.10.2 | Pre-fork | Supported | Snapshot/Restore (maintenance window) OR MA HDM | Snapshot/Restore is the simplest path while license boundary allows |
| ES ≥ 7.11 (7.11–7.17, 8.x) | Post-fork ELv2/SSPL | BLOCKED (license lockout) | MA HDM (large/complex) or _reindex from remote (small, ≥30 min window) | Snapshot/Restore is architecturally blocked post-fork |
Source/target version eligibility for each MA mode: see Migration Assistant source-and-target versions (opens in a new tab)
[verify].
Every row below MUST be evaluated for every ES source migration. Copy confirmed findings into the gap register (elasticsearch-gap-register.md). Severity + Lane vocabulary from compatibility-rubric.md.
| Feature | Elasticsearch behavior | OpenSearch alternative | Severity | Lane | Notes |
|---|---|---|---|---|---|
Index Lifecycle Management (_ilm/policy) | ILM policy JSON | ISM (_plugins/_ism/policies) — policy JSON does NOT import | HIGH | risk-blocker | Rebuild each ILM policy as ISM; common patterns: rollover, force_merge, warm/cold, delete |
| X-Pack Watcher | Rule-based alerting | OpenSearch Alerting monitors + destinations | HIGH | risk-blocker | Rebuild monitors; smoke-test trigger conditions |
| Runtime fields (schema-on-read) | runtime mapping type | No equivalent | HIGH | risk-blocker | Pre-compute via ingest pipeline or scripted_field; reindex |
| Fleet / Elastic Agent | X-Pack ingest + endpoint management | No equivalent on AOS | BLOCKING | risk-blocker | Re-architect ingest on Data Prepper / OSI / Fluent Bit / OTel Collector |
ELSER text_expansion | Elastic learned sparse retrieval (proprietary) | neural_sparse query + SageMaker-hosted sparse encoder | HIGH | risk-blocker | ELSER does not run on AOS; use neural_sparse or hybrid BM25+dense |
dense_vector field | Dense vector + kNN | knn_vector (engine selection: see vector-knn.md) | MEDIUM | migration-specific | Pick engine (FAISS/Lucene/NMSLIB); reindex; validate recall |
_type / multi-type mappings | ES 6.x multi-type or 7.x _doc placeholder | Types removed in OS 1.0; _doc placeholder OKs in 7.x but blows up _reindex | MEDIUM | migration-specific | MA metadata transformer flattens templates automatically |
fielddata: true on text (ES 1.x/2.x) | In-memory fielddata for sort/agg | .keyword subfield + doc_values | BLOCKING | migration-specific | OOM risk on first aggregation; MA transformer strips fielddata and adds .keyword automatically |
_source: {enabled: false} | _source not stored | Forces MA Historical Data Migration only — Snapshot/Restore cannot reconstruct | HIGH | risk-blocker | Use MA HDM; re-enable _source on target index |
ES 8 retriever / rrf | Native reciprocal-rank fusion | Hybrid query + normalization-processor pipeline | HIGH | risk-blocker | Rebuild as hybrid search pipeline; benchmark ranking parity |
| Snapshot from ES ≥ 7.11 | Snapshot archive | BLOCKED — ELv2/SSPL license lockout into AOS | BLOCKING | risk-blocker | Use MA HDM or _reindex from remote |
Open Distro plugin names (opendistro-*) | opendistro-* plugin namespace | opensearch-* rename | LOW | migration-specific | Plugin namespace rename is mechanical; validate config files |
Use as the audit checklist for §2 Schema/Mapping in the report and for elasticsearch-index-template-skeleton.md.
| ES construct | OpenSearch equivalent | Action |
|---|---|---|
type: text with fielddata: true | type: text + .keyword subfield | Strip fielddata; add keyword subfield |
type: flattened | type: flat_object | Rename type |
type: dense_vector | type: knn_vector | Change type + add engine/method parameters |
type: runtime (runtime fields) | No equivalent | Pre-compute via ingest pipeline |
Multi-type index (_type) | Single-type; _type removed | MA metadata transformer flattens automatically |
_source: {enabled: false} | Supported but blocks Snapshot/Restore | Re-enable on target or use MA HDM |
index_patterns (index template) | index_patterns (identical) | No change |
_ilm lifecycle hooks in index settings | ISM policy attachment | Rewrite ILM → ISM; re-attach |
| ES API | OpenSearch API | Notes |
|---|---|---|
GET /_ilm/policy | GET /_plugins/_ism/policies | JSON format differs; rebuild required |
GET /_watcher/watch | GET /_plugins/_alerting/monitors | Rebuild required |
GET /_xpack | Not applicable | No X-Pack on AOS |
GET /_eql/search | GET /_plugins/ppl | Use PPL for log analytics; EQL not available |
GET /_async_search | GET /_plugins/_asynchronous_search | Semantics match; endpoint differs |
GET /_text_expansion (ELSER) | GET /_plugins/ml (neural_sparse) | Model hosting required on AOS side |
_reindex threshold — prefer _reindex from remote for post-fork ES when dataset is small and a ≥30 min maintenance window is available. MA HDM becomes primary for large/complex datasets or when source→target network reachability is not possible.fielddata: true OOM risk — flag on every ES 1.x/2.x source even if MA handles it automatically.