#!/usr/bin/env python3 """ Generate HTML redirect files from redirects.json. Usage: python generate_redirects.py This script reads redirects.json and generates individual HTML files for each redirect path. Each HTML file uses meta refresh (0 delay) which is SEO-friendly and treated similarly to 301 redirects by Google. To add new redirects, simply edit redirects.json and re-run this script. """ import http.client import json import os import urllib.error import urllib.parse import urllib.request from pathlib import Path # Default fallback URL for any path not in the redirect map DEFAULT_REDIRECT = "https://docs.langchain.com/oss/python/langgraph/overview" # The docs site regenerates this index on every deploy, so fetching it here # keeps the published llms.txt from drifting. The URL is a hardcoded constant, # never built from input, and both it and the post-redirect URL are checked # against ALLOWED_LLMS_HOST before anything is read. CANONICAL_LLMS_URL = "https://docs.langchain.com/oss/python/langgraph/llms.txt" ALLOWED_LLMS_HOST = "docs.langchain.com" LLMS_FETCH_TIMEOUT = 30 LLMS_MAX_BYTES = 1_000_000 HTML_TEMPLATE = """ Redirecting... Redirecting... """ ROOT_HTML_TEMPLATE = """ Redirecting to LangGraph Documentation

Documentation has moved

The LangGraph documentation has moved to docs.langchain.com.

Redirecting you now...

""" CATCHALL_404_TEMPLATE = """ Redirecting to LangGraph Documentation

Documentation has moved

The LangGraph documentation has moved to docs.langchain.com.

Redirecting you now...

""" def is_allowed_llms_url(url): """Return True if url is HTTPS on the one host we accept content from.""" parsed = urllib.parse.urlsplit(url) return parsed.scheme == "https" and parsed.hostname == ALLOWED_LLMS_HOST def fetch_canonical_llms_txt(): """Return the published LangGraph index, or None if it cannot be used. Returning None leaves the caller on the committed docs/llms.txt, so a docs.langchain.com outage degrades to a stale file rather than a broken deploy or a published error page. """ if not is_allowed_llms_url(CANONICAL_LLMS_URL): print(f"Refusing to fetch {CANONICAL_LLMS_URL}: host not allowed") return None try: with urllib.request.urlopen( # noqa: S310 - constant, allowlisted URL CANONICAL_LLMS_URL, timeout=LLMS_FETCH_TIMEOUT ) as response: # urlopen follows redirects, so re-check where it actually landed. if not is_allowed_llms_url(response.url): print(f"Refusing {CANONICAL_LLMS_URL}: redirected to {response.url}") return None body = response.read(LLMS_MAX_BYTES + 1) # A connection dropped mid-body raises http.client.IncompleteRead, which # descends from HTTPException rather than OSError, so catching only the # urllib and OS errors would let it escape and fail the whole deploy. except ( urllib.error.URLError, http.client.HTTPException, TimeoutError, OSError, ) as exc: print(f"Could not fetch {CANONICAL_LLMS_URL}: {type(exc).__name__}: {exc}") return None if len(body) > LLMS_MAX_BYTES: print(f"Refusing {CANONICAL_LLMS_URL}: larger than {LLMS_MAX_BYTES} bytes") return None try: text = body.decode("utf-8") except UnicodeDecodeError as exc: print(f"Refusing {CANONICAL_LLMS_URL}: not valid UTF-8: {exc}") return None # An index opens with a markdown heading and links to the docs site. A # body that does not is an error page or a truncated response, not content # worth publishing. if not text.startswith("# ") or f"https://{ALLOWED_LLMS_HOST}/" not in text: print(f"Refusing {CANONICAL_LLMS_URL}: does not look like an llms.txt index") return None return text def generate_redirects(): script_dir = Path(__file__).parent output_dir = script_dir / "_site" # Load redirects with open(script_dir / "redirects.json") as f: redirects = json.load(f) # Clean output directory if output_dir.exists(): import shutil shutil.rmtree(output_dir) output_dir.mkdir(parents=True) # Generate individual HTML files for each redirect for old_path, new_url in redirects.items(): # Remove leading slash and create directory structure path = old_path.lstrip("/") # Check if path has a file extension (e.g., .txt, .xml) # If so, create the file directly instead of a directory with index.html path_obj = Path(path) has_extension = path_obj.suffix and len(path_obj.suffix) <= 5 if not path: html_path = output_dir / "index.html" elif has_extension: # For files with extensions, create the file directly html_path = output_dir / path else: # For directory-style URLs, create index.html inside html_path = output_dir / path / "index.html" # Create parent directories html_path.parent.mkdir(parents=True, exist_ok=True) # Write the redirect HTML html_path.write_text(HTML_TEMPLATE.format(url=new_url)) print(f"Created: {html_path}") # Create root index.html root_index = output_dir / "index.html" if not root_index.exists(): root_index.write_text(ROOT_HTML_TEMPLATE.format(url=DEFAULT_REDIRECT)) print(f"Created: {root_index}") # Create 404.html for catchall catchall_404 = output_dir / "404.html" catchall_404.write_text(CATCHALL_404_TEMPLATE.format(default_url=DEFAULT_REDIRECT)) print(f"Created: {catchall_404}") # llms.txt can't be redirected via HTML, so publish the docs site's own # generated index. The committed copy is only a fallback. llms_txt = fetch_canonical_llms_txt() if llms_txt is not None: (output_dir / "llms.txt").write_text(llms_txt) print(f"Fetched: {output_dir / 'llms.txt'} (from {CANONICAL_LLMS_URL})") else: src = script_dir / "llms.txt" if src.exists(): (output_dir / "llms.txt").write_text(src.read_text()) print(f"Copied: {output_dir / 'llms.txt'} (fallback, may be stale)") else: print("No llms.txt fetched and no committed fallback; skipping") print(f"\nGenerated {len(redirects)} redirect files in {output_dir}") if __name__ == "__main__": generate_redirects()