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The same URL can reach downloadTarball_() in different encodings, e.g. `+` vs. `%2B`. Cache keys were inconsistent about this: * The lookup key was the URL string as passed in. * The insert keys were the URLs in the redirect chain returned by the file transfer. The first one is `request.uri.to_string()`, which is re-encoded by ParsedURL (`+` becomes `%2B`), while the subsequent ones are curl's effective URLs, which are the `Location` headers verbatim. This caused cache misses for FlakeHub flakes. E.g. https://flakehub.com/f/NixOS/nixpkgs/0.2605 redirects to https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.2605.1017737+rev-.../source.tar.gz, which is cached with the `+`. However, the locked URL that ends up in flake.lock goes through ParsedURL and so contains `%2B`. As a result, the next command missed the cache and downloaded the tarball again. Conversely, a tarball URL with a `+` passed to `fetchTree` was looked up verbatim but inserted with `%2B`, so it never hit the cache. The fix is to canonicalise all URLs used as cache keys via ParsedURL::to_string(). Since the first URL in the redirect chain was already canonical, existing cache entries for it remain valid. Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>
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Motivation
After
nix flake updateon a FlakeHub input likehttps://flakehub.com/f/NixOS/nixpkgs/0.2605, the next command missed the tarball cache and downloaded nixpkgs again. The cache entry was keyed on the redirect target as sent by the server (.../0.2605.1017737+rev-.../source.tar.gz), while the locked URL inflake.lockhas%2Brev-. Similarly,fetchTreeon a tarball URL containing a+never hit the cache.Taken from DeterminateSystems#760.
Implementation
Use the canonical encoding of the URL (
ParsedURL::to_string()) both for the cache lookup and for every URL in the redirect chain on insert. Existing cache entries for the original request URL stay valid, since those were already canonical.Tests: a functional test for a
+in afile://tarball URL, and thetarball-flakesNixOS test now redirects to a+URL and checks that the locked URL is fetched from the cache with the web server stopped.Add 👍 to pull requests you find important.
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