josh
7d1649d278
Per-file content-hash versioning on every /static reference, immutable cache headers on versioned URLs, no-cache on HTML, auto-bumped service worker cache name with stale-while-revalidate for assets, and a controllerchange listener that silently reloads the page when a new SW takes control. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
84 lines
2.4 KiB
Python
84 lines
2.4 KiB
Python
import hashlib
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import logging
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import time
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from pathlib import Path
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from flask import Flask, request
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from app.config import LOG_LEVEL
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logging.basicConfig(
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level=getattr(logging, LOG_LEVEL.upper(), logging.INFO),
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format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
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datefmt="%Y-%m-%d %H:%M:%S",
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)
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app = Flask(__name__)
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# ── Static asset versioning ────────────────────────────────────────
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# Each /static/<file> reference gets a ?v=<hash> query string so we can serve
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# it with `Cache-Control: immutable` and still bust the cache when bytes change.
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_FALLBACK_TOKEN = hashlib.sha1(str(time.time()).encode()).hexdigest()[:8]
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_static_hashes: dict[str, str] = {}
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def _hash_file(path: Path) -> str:
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h = hashlib.sha1()
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with path.open("rb") as fh:
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for chunk in iter(lambda: fh.read(65536), b""):
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h.update(chunk)
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return h.hexdigest()[:8]
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def static_hash(filename: str) -> str:
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if filename in _static_hashes:
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return _static_hashes[filename]
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path = Path(app.static_folder) / filename
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try:
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token = _hash_file(path)
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except OSError:
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logging.getLogger(__name__).warning(
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"static_hash: cannot hash %s, using fallback token", filename
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)
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return _FALLBACK_TOKEN
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_static_hashes[filename] = token
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return token
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def static_v(filename: str) -> str:
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return f"/static/{filename}?v={static_hash(filename)}"
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_static_dir = Path(app.static_folder)
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if _static_dir.is_dir():
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for _path in sorted(_static_dir.iterdir()):
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if _path.is_file():
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try:
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_static_hashes[_path.name] = _hash_file(_path)
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except OSError:
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continue
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APP_VERSION = (
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hashlib.sha1(
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"|".join(f"{n}:{h}" for n, h in sorted(_static_hashes.items())).encode()
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).hexdigest()[:8]
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if _static_hashes
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else _FALLBACK_TOKEN
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)
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app.jinja_env.globals["static_v"] = static_v
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@app.after_request
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def _add_cache_headers(response):
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if response.mimetype == "text/html":
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response.headers["Cache-Control"] = "no-cache, must-revalidate"
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return response
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if request.path.startswith("/static/") and request.args.get("v"):
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response.headers["Cache-Control"] = "public, max-age=31536000, immutable"
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return response
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from app import routes # noqa: E402, F401
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