feat(llm): add AWS Bedrock reranker connector (#16960)

## What

Adds a reranker connector for the **Bedrock** factory, which previously
offered
chat/embedding/CV models but no reranker — selecting a Bedrock rerank
model
raised `Factory not in rerank model`.

## How

`BedrockRerank` calls the `bedrock-agent-runtime` Rerank API. It reuses
the same
JSON key protocol as `BedrockEmbed` (`auth_mode` / `bedrock_region` /
`bedrock_ak` / `bedrock_sk`, with `access_key_secret` / `iam_role` /
`assume_role` modes). Documents are truncated to the model window
(Cohere Rerank
v3.5 ~2k of its shared 4k window, Amazon Rerank v1 8k) on top of
Bedrock's own
internal truncation. Scores are returned in `[0, 1]`, so the shared
`Base.similarity` normalization applies unchanged.

Verified against `amazon.rerank-v1:0` and `cohere.rerank-v3-5:0` in
`eu-central-1`.

> Note: this PR adds the connector only. Bedrock rerank models can be
selected by
> adding the relevant entries to `conf/llm_factories.json` under the
Bedrock
> provider; that catalog change is intentionally left out of this PR.

## Tests

`test/unit_test/rag/llm/test_bedrock_rerank.py` — boto3 is mocked (no
AWS call):
score-by-index mapping, per-model document truncation, model ARN
construction,
auth-mode validation and the empty-input short-circuit. `pytest` green
alongside
the existing reranker normalization suite.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
This commit is contained in:
VincentLambert
2026-07-16 05:06:20 +02:00
committed by GitHub
parent 047c714ffb
commit 8f87e19120
2 changed files with 285 additions and 0 deletions

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@@ -15,6 +15,7 @@
#
import json
import logging
import time
from abc import ABC
from urllib.parse import urljoin
from typing import Tuple, List
@@ -298,6 +299,112 @@ class CoHereRerank(Base):
return rank, token_count
# Reranker connector for AWS Bedrock, calling the bedrock-agent-runtime Rerank
# API (e.g. amazon.rerank-v1:0, cohere.rerank-v3-5:0). The JSON key protocol
# (auth_mode / bedrock_region / bedrock_ak / bedrock_sk) mirrors BedrockEmbed in
# embedding_model.py.
class BedrockRerank(Base):
_FACTORY_NAME = "Bedrock"
# Hard limits of the bedrock-agent-runtime Rerank API: each document text
# (RerankTextDocument.text) is capped at 32,000 characters, and a single
# request accepts at most 1,000 sources / numberOfResults.
_MAX_DOC_CHARS = 32000
_MAX_SOURCES = 1000
def __init__(self, key, model_name, **kwargs):
import boto3
key = json.loads(key)
mode = key.get("auth_mode")
if not mode:
logging.error("Bedrock auth_mode is not provided in the key")
raise ValueError("Bedrock auth_mode must be provided in the key")
self.bedrock_region = key.get("bedrock_region")
self.model_name = model_name
# On-demand foundation-model ARN; works for amazon.rerank-v1:0 / cohere.rerank-*.
self.model_arn = f"arn:aws:bedrock:{self.bedrock_region}::foundation-model/{self.model_name}"
# Per-document truncation guard sized to the model window. Cohere Rerank
# v3.5 shares a ~4k window between query and document (~2048 for docs);
# Amazon Rerank v1 handles 32k, but chunks are small so a generous cap
# just bounds pathological payloads. Bedrock also truncates internally.
self.doc_max_tokens = 2048 if self.model_name.split(".")[0] == "cohere" else 8192
# Rerank lives on the bedrock-agent-runtime service, not bedrock-runtime.
if mode == "access_key_secret":
self.client = boto3.client(
service_name="bedrock-agent-runtime",
region_name=self.bedrock_region,
aws_access_key_id=key.get("bedrock_ak"),
aws_secret_access_key=key.get("bedrock_sk"),
)
elif mode == "iam_role":
sts_client = boto3.client("sts", region_name=self.bedrock_region)
resp = sts_client.assume_role(RoleArn=key.get("aws_role_arn"), RoleSessionName="BedrockSession")
creds = resp["Credentials"]
self.client = boto3.client(
service_name="bedrock-agent-runtime",
region_name=self.bedrock_region,
aws_access_key_id=creds["AccessKeyId"],
aws_secret_access_key=creds["SecretAccessKey"],
aws_session_token=creds["SessionToken"],
)
else: # assume_role: default AWS credential chain
self.client = boto3.client("bedrock-agent-runtime", region_name=self.bedrock_region)
def _compute_rank(self, query: str, texts: List) -> Tuple[np.ndarray, int]:
# Truncate to the model token window, then enforce the API's hard 32k-char
# per-text limit (a longer RerankTextQuery / RerankTextDocument is rejected).
query = query[: self._MAX_DOC_CHARS]
texts = [truncate(t, self.doc_max_tokens)[: self._MAX_DOC_CHARS] for t in texts]
# Bedrock does not report token usage; count locally like CoHereRerank.
token_count = num_tokens_from_string(query) + sum(num_tokens_from_string(t) for t in texts)
rank = np.zeros(len(texts), dtype=float)
result_count = 0
started = time.perf_counter()
# Both `sources` and `numberOfResults` are capped at 1,000 per request;
# rerank in batches and map each score back to its global position.
for offset in range(0, len(texts), self._MAX_SOURCES):
batch = texts[offset : offset + self._MAX_SOURCES]
sources = [{"type": "INLINE", "inlineDocumentSource": {"type": "TEXT", "textDocument": {"text": t}}} for t in batch]
reranking_config = {
"type": "BEDROCK_RERANKING_MODEL",
"bedrockRerankingConfiguration": {
"numberOfResults": len(batch),
"modelConfiguration": {"modelArn": self.model_arn},
},
}
# Drain paginated results: the API may split a batch across nextToken pages.
next_token = None
while True:
request = {"queries": [{"type": "TEXT", "textQuery": {"text": query}}], "sources": sources, "rerankingConfiguration": reranking_config}
if next_token:
request["nextToken"] = next_token
res = self.client.rerank(**request)
try:
for d in res.get("results", []):
rank[offset + d["index"]] = d["relevanceScore"]
result_count += 1
except (KeyError, IndexError, TypeError) as _e:
log_exception(_e, res)
next_token = res.get("nextToken")
if not next_token:
break
# Safe diagnostics only: no query, document text or credentials.
logging.debug(
"BedrockRerank model=%s region=%s sources=%d tokens=%d results=%d elapsed=%.3fs",
self.model_name,
self.bedrock_region,
len(texts),
token_count,
result_count,
time.perf_counter() - started,
)
return rank, token_count
class TogetherAIRerank(Base):
_FACTORY_NAME = "TogetherAI"

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@@ -0,0 +1,178 @@
#
# Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""Unit tests for the AWS Bedrock reranker connector.
``BedrockRerank`` talks to the ``bedrock-agent-runtime`` Rerank API via boto3.
These tests patch ``boto3.client`` so no AWS call is made, and verify the
score-by-index mapping, per-model document truncation and key/ARN handling.
"""
import json
from unittest.mock import MagicMock, patch
import numpy as np
import pytest
from common.token_utils import num_tokens_from_string
from rag.llm.rerank_model import BedrockRerank
pytestmark = pytest.mark.p1
KEY = json.dumps(
{
"auth_mode": "access_key_secret",
"bedrock_region": "eu-central-1",
"bedrock_ak": "AKIA_TEST",
"bedrock_sk": "secret_test",
}
)
def _rerank_response(scores):
"""Bedrock returns results out of order; ``index`` maps back to the source doc."""
return {"results": [{"index": i, "relevanceScore": s} for i, s in scores]}
def _make(model_name="amazon.rerank-v1:0", key=KEY):
"""Instantiate the connector with ``boto3.client`` patched; return (model, client)."""
with patch("boto3.client") as client_factory:
client = MagicMock()
client_factory.return_value = client
mdl = BedrockRerank(key, model_name)
return mdl, client
def test_scores_are_mapped_back_by_index():
mdl, client = _make()
# Response deliberately out of source order.
client.rerank.return_value = _rerank_response([(2, 0.9), (0, 0.1), (1, 0.5)])
rank, _ = mdl.similarity("q", ["a", "b", "c"])
assert np.allclose(rank, [0.1, 0.5, 0.9])
def test_model_arn_is_built_from_region_and_name():
mdl, _ = _make(model_name="cohere.rerank-v3-5:0")
assert mdl.model_arn == "arn:aws:bedrock:eu-central-1::foundation-model/cohere.rerank-v3-5:0"
def test_doc_window_depends_on_model():
cohere, _ = _make(model_name="cohere.rerank-v3-5:0")
amazon, _ = _make(model_name="amazon.rerank-v1:0")
assert cohere.doc_max_tokens == 2048
assert amazon.doc_max_tokens == 8192
def test_documents_are_truncated_before_send():
mdl, client = _make(model_name="cohere.rerank-v3-5:0") # cap 2048
client.rerank.return_value = _rerank_response([(0, 0.5)])
mdl.similarity("q", ["mot " * 5000]) # > 2048 tokens
sent = client.rerank.call_args.kwargs["sources"][0]["inlineDocumentSource"]["textDocument"]["text"]
assert num_tokens_from_string(sent) <= 2048
def test_number_of_results_covers_all_documents():
mdl, client = _make()
client.rerank.return_value = _rerank_response([(0, 0.3), (1, 0.6)])
mdl.similarity("q", ["a", "b"])
cfg = client.rerank.call_args.kwargs["rerankingConfiguration"]["bedrockRerankingConfiguration"]
assert cfg["numberOfResults"] == 2
assert cfg["modelConfiguration"]["modelArn"].endswith("amazon.rerank-v1:0")
def test_missing_auth_mode_raises():
with patch("boto3.client"):
with pytest.raises(ValueError):
BedrockRerank(json.dumps({"bedrock_region": "eu-central-1"}), "amazon.rerank-v1:0")
def test_access_key_secret_mode_wires_the_client():
with patch("boto3.client") as client_factory:
client_factory.return_value = MagicMock()
BedrockRerank(KEY, "amazon.rerank-v1:0")
kwargs = client_factory.call_args.kwargs
assert kwargs["service_name"] == "bedrock-agent-runtime"
assert kwargs["region_name"] == "eu-central-1"
assert kwargs["aws_access_key_id"] == "AKIA_TEST"
assert kwargs["aws_secret_access_key"] == "secret_test"
@pytest.mark.parametrize("query, texts", [("", ["a"]), ("q", [])])
def test_empty_input_short_circuits_without_calling_bedrock(query, texts):
mdl, client = _make()
rank, tokens = mdl.similarity(query, texts)
assert tokens == 0
assert rank.size == len(texts)
client.rerank.assert_not_called()
def test_document_is_capped_at_32000_chars():
# RerankTextDocument.text is hard-capped at 32,000 chars; a longer doc would
# otherwise be rejected by the API. Amazon's 8k-token window can exceed it.
mdl, client = _make(model_name="amazon.rerank-v1:0")
client.rerank.return_value = _rerank_response([(0, 0.5)])
mdl.similarity("q", ["word " * 30000]) # 150k chars -> ~41k after token truncation
sent = client.rerank.call_args.kwargs["sources"][0]["inlineDocumentSource"]["textDocument"]["text"]
assert len(sent) == 32000
def test_query_is_capped_at_32000_chars():
mdl, client = _make(model_name="amazon.rerank-v1:0")
client.rerank.return_value = _rerank_response([(0, 0.5)])
mdl.similarity("q " * 30000, ["doc"]) # oversize query
sent = client.rerank.call_args.kwargs["queries"][0]["textQuery"]["text"]
assert len(sent) == 32000
def test_short_document_is_not_char_capped():
mdl, client = _make(model_name="amazon.rerank-v1:0")
client.rerank.return_value = _rerank_response([(0, 0.5)])
mdl.similarity("q", ["short document"])
sent = client.rerank.call_args.kwargs["sources"][0]["inlineDocumentSource"]["textDocument"]["text"]
assert sent == "short document"
def test_batches_requests_over_the_1000_source_limit():
mdl, client = _make()
def _fake_rerank(**kwargs):
n = len(kwargs["sources"])
return {"results": [{"index": i, "relevanceScore": 0.5} for i in range(n)]}
client.rerank.side_effect = _fake_rerank
n = 2001
rank, _ = mdl.similarity("q", ["doc"] * n)
assert rank.shape == (n,)
assert client.rerank.call_count == 3 # 1000 + 1000 + 1
for call in client.rerank.call_args_list:
cfg = call.kwargs["rerankingConfiguration"]["bedrockRerankingConfiguration"]
sources = call.kwargs["sources"]
assert len(sources) <= 1000
assert cfg["numberOfResults"] == len(sources)
def test_paginated_results_are_all_consumed():
mdl, client = _make()
# First page returns one score + a nextToken; second page returns the rest.
pages = [
{"results": [{"index": 0, "relevanceScore": 0.9}], "nextToken": "tok"},
{"results": [{"index": 1, "relevanceScore": 0.4}, {"index": 2, "relevanceScore": 0.1}]},
]
client.rerank.side_effect = pages
rank, _ = mdl.similarity("q", ["a", "b", "c"])
assert client.rerank.call_count == 2
assert client.rerank.call_args_list[1].kwargs["nextToken"] == "tok"
assert np.allclose(rank, [0.9, 0.4, 0.1])