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author | Alyssa Ross <hi@alyssa.is> | 2023-11-16 12:53:32 +0100 |
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committer | Alyssa Ross <hi@alyssa.is> | 2023-11-16 12:53:32 +0100 |
commit | 67419f0e56f99b0ebbe14574d3492110ac84c8d6 (patch) | |
tree | 3abc8e1606a2c80b6f5d14fef175e50800202163 /nixpkgs/doc/packages/nginx.section.md | |
parent | a2c1eff83c3118a9aee8076c7f84f58137416b6e (diff) | |
parent | 9008bc4eb62c878d0812105ea1b34255d651df88 (diff) | |
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Merge branch 'nixos-unstable-small' of https://github.com/NixOS/nixpkgs into HEAD
Diffstat (limited to 'nixpkgs/doc/packages/nginx.section.md')
-rw-r--r-- | nixpkgs/doc/packages/nginx.section.md | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/nixpkgs/doc/packages/nginx.section.md b/nixpkgs/doc/packages/nginx.section.md new file mode 100644 index 000000000000..0704b534e5f7 --- /dev/null +++ b/nixpkgs/doc/packages/nginx.section.md @@ -0,0 +1,11 @@ +# Nginx {#sec-nginx} + +[Nginx](https://nginx.org) is a reverse proxy and lightweight webserver. + +## ETags on static files served from the Nix store {#sec-nginx-etag} + +HTTP has a couple of different mechanisms for caching to prevent clients from having to download the same content repeatedly if a resource has not changed since the last time it was requested. When nginx is used as a server for static files, it implements the caching mechanism based on the [`Last-Modified`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Last-Modified) response header automatically; unfortunately, it works by using filesystem timestamps to determine the value of the `Last-Modified` header. This doesn't give the desired behavior when the file is in the Nix store because all file timestamps are set to 0 (for reasons related to build reproducibility). + +Fortunately, HTTP supports an alternative (and more effective) caching mechanism: the [`ETag`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag) response header. The value of the `ETag` header specifies some identifier for the particular content that the server is sending (e.g., a hash). When a client makes a second request for the same resource, it sends that value back in an `If-None-Match` header. If the ETag value is unchanged, then the server does not need to resend the content. + +As of NixOS 19.09, the nginx package in Nixpkgs is patched such that when nginx serves a file out of `/nix/store`, the hash in the store path is used as the `ETag` header in the HTTP response, thus providing proper caching functionality. This happens automatically; you do not need to do modify any configuration to get this behavior. |