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#!/usr/bin/env python3
"""A complete RAG pipeline over real documentation — zero dependencies.
Retrieval-augmented generation against XERJ's own manual: strips the HTML
docs that ship in this repo (landing/docs/*.html), chunks them with
overlap, indexes every chunk into a `semantic_text` field (XERJ embeds at
ingest — no API keys needed), and answers questions with hybrid retrieval
(BM25 + semantic, RRF-fused) plus citations.
Works fully offline. If you export an OpenAI-compatible chat endpoint the
final answer is generated by an LLM grounded in the retrieved chunks;
otherwise the recipe prints the retrieved passages (extractive mode).
Run it:
xerj --insecure --data-dir ./data & # start XERJ
python3 recipes/rag_app.py # index + eval + one answer
python3 recipes/rag_app.py "your question here"
Optional env:
XERJ_URL (default http://localhost:9200)
LLM_ENDPOINT OpenAI-compatible /v1/chat/completions URL
LLM_API_KEY bearer token for LLM_ENDPOINT
LLM_MODEL (default gpt-4o-mini)
"""
import html.parser
import json
import os
import pathlib
import re
import sys
import urllib.error
import urllib.request
XERJ = os.environ.get("XERJ_URL", "http://localhost:9200")
DOCS = pathlib.Path(__file__).resolve().parent.parent / "landing" / "docs"
INDEX = "xerj-manual"
CHUNK_CHARS, OVERLAP = 900, 150
def call(method: str, path: str, body=None):
data = None
headers = {}
if body is not None:
data = body.encode() if isinstance(body, str) else json.dumps(body).encode()
headers["Content-Type"] = (
"application/x-ndjson" if isinstance(body, str) else "application/json"
)
req = urllib.request.Request(f"{XERJ}{path}", data=data, headers=headers, method=method)
with urllib.request.urlopen(req) as resp:
return json.loads(resp.read())
# ── 1. Turn the shipped HTML docs into plain text ───────────────────────────
class TextExtractor(html.parser.HTMLParser):
"""Keep visible text from <main>, drop scripts/styles/nav."""
SKIP = {"script", "style", "nav", "footer", "header"}
def __init__(self):
super().__init__()
self.parts, self._skip_depth, self.title = [], 0, ""
self._in_title = False
def handle_starttag(self, tag, attrs):
if tag in self.SKIP:
self._skip_depth += 1
if tag == "title":
self._in_title = True
def handle_endtag(self, tag):
if tag in self.SKIP and self._skip_depth:
self._skip_depth -= 1
if tag == "title":
self._in_title = False
def handle_data(self, data):
if self._in_title:
self.title += data
elif not self._skip_depth:
self.parts.append(data)
def page_text(path: pathlib.Path):
p = TextExtractor()
p.feed(path.read_text(errors="ignore"))
text = re.sub(r"\s+", " ", " ".join(p.parts)).strip()
title = p.title.split("·")[-1].strip() or path.stem
return title, text
def chunk(text: str):
"""Overlapping chunks, preferring sentence boundaries — the same idea
XERJ's internal ingest chunker uses."""
out, start = [], 0
while start < len(text):
end = min(start + CHUNK_CHARS, len(text))
if end < len(text):
cut = text.rfind(". ", start, end)
if cut > start + CHUNK_CHARS // 2:
end = cut + 1
out.append(text[start:end].strip())
if end >= len(text):
break
start = end - OVERLAP
return out
def build_index():
try:
call("DELETE", f"/{INDEX}")
except urllib.error.HTTPError:
pass
call("PUT", f"/{INDEX}", {
"mappings": {
"properties": {
"page": {"type": "keyword"},
"title": {"type": "keyword"},
"text": {"type": "semantic_text", "dimensions": 384},
}
}
})
lines, n_pages = [], 0
for f in sorted(DOCS.glob("*.html")):
title, text = page_text(f)
if len(text) < 200:
continue
n_pages += 1
for i, c in enumerate(chunk(text)):
lines.append(json.dumps({"index": {"_index": INDEX, "_id": f"{f.stem}-{i}"}}))
lines.append(json.dumps({"page": f.stem, "title": title, "text": c}))
call("POST", "/_bulk?refresh=true", "\n".join(lines) + "\n")
print(f"indexed {len(lines) // 2} chunks from {n_pages} real docs pages\n")
# ── 2. Retrieval: hybrid = BM25 + semantic, fused with RRF ──────────────────
def retrieve(question: str, k: int = 4):
hits = call("POST", f"/{INDEX}/_search", {
"size": k,
"query": {"hybrid": {"queries": [
{"query": {"match": {"text": question}}, "weight": 1.0},
{"query": {"semantic": {"field": "text", "query": question, "k": 20}}, "weight": 1.0},
]}},
})["hits"]["hits"]
return [(h["_source"]["page"], h["_source"]["title"], h["_source"]["text"]) for h in hits]
# ── 3. Generation: LLM if configured, extractive otherwise ─────────────────
def answer(question: str):
ctx = retrieve(question)
print(f"Q: {question}\n")
endpoint = os.environ.get("LLM_ENDPOINT")
if endpoint:
prompt = "Answer strictly from the context.\n\n" + "\n---\n".join(t for _, _, t in ctx)
req = urllib.request.Request(
endpoint,
data=json.dumps({
"model": os.environ.get("LLM_MODEL", "gpt-4o-mini"),
"messages": [
{"role": "system", "content": prompt},
5B92
{"role": "user", "content": question},
],
}).encode(),
headers={
"Content-Type": "application/json",
"Authorization": f"Bearer {os.environ.get('LLM_API_KEY', '')}",
},
)
with urllib.request.urlopen(req) as resp:
print(json.loads(resp.read())["choices"][0]["message"]["content"], "\n")
else:
print("(no LLM_ENDPOINT set — extractive mode)\n")
for page, title, text in ctx[:2]:
print(f" {text[:300]}…\n")
print("sources:", ", ".join(dict.fromkeys(f"docs/{p}.html" for p, _, _ in ctx)), "\n")
# ── 4. A tiny honest retrieval eval on real questions ──────────────────────
EVAL = [
("how do I run xerj as a systemd service?", "install"),
("which quantization modes exist for vectors?", "vectors"),
("how do I migrate an existing Elasticsearch index?", "migration-from-es"),
("what does the bool query's filter clause do?", "queries"),
("how do I take a backup to S3?", "backup-restore"),
]
def run_eval():
ok = 0
for q, expect in EVAL:
pages = [p for p, _, _ in retrieve(q, k=3)]
hit = expect in pages
ok += hit
print(f" {'✓' if hit else '✗'} {q} → {pages}")
print(f"\nretrieval hit@3: {ok}/{len(EVAL)}\n")
if __name__ == "__main__":
build_index()
if len(sys.argv) > 1:
answer(" ".join(sys.argv[1:]))
else:
run_eval()
answer("how do I keep memory usage down on a vector-heavy index?")