diff options
-rw-r--r-- | doc/builders/packages/index.xml | 2 | ||||
-rw-r--r-- | doc/builders/packages/nginx.section.md | 11 | ||||
-rw-r--r-- | doc/builders/packages/nginx.xml | 25 |
3 files changed, 12 insertions, 26 deletions
diff --git a/doc/builders/packages/index.xml b/doc/builders/packages/index.xml index ba59ceb016b6..44e89169629d 100644 --- a/doc/builders/packages/index.xml +++ b/doc/builders/packages/index.xml @@ -14,7 +14,7 @@ <xi:include href="kakoune.section.xml" /> <xi:include href="linux.xml" /> <xi:include href="locales.xml" /> - <xi:include href="nginx.xml" /> + <xi:include href="nginx.section.xml" /> <xi:include href="opengl.section.xml" /> <xi:include href="shell-helpers.xml" /> <xi:include href="steam.xml" /> diff --git a/doc/builders/packages/nginx.section.md b/doc/builders/packages/nginx.section.md new file mode 100644 index 000000000000..154c21f9b369 --- /dev/null +++ b/doc/builders/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 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. diff --git a/doc/builders/packages/nginx.xml b/doc/builders/packages/nginx.xml deleted file mode 100644 index 65854ba02366..000000000000 --- a/doc/builders/packages/nginx.xml +++ /dev/null @@ -1,25 +0,0 @@ -<section xmlns="http://docbook.org/ns/docbook" - xmlns:xlink="http://www.w3.org/1999/xlink" - xml:id="sec-nginx"> - <title>Nginx</title> - - <para> - <link xlink:href="https://nginx.org/">Nginx</link> is a reverse proxy and lightweight webserver. - </para> - - <section xml:id="sec-nginx-etag"> - <title>ETags on static files served from the Nix store</title> - - <para> - HTTP has a couple 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 <link xlink:href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Last-Modified"><literal>Last-Modified</literal></link> response header automatically; unfortunately, it works by using filesystem timestamps to determine the value of the <literal>Last-Modified</literal> 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). - </para> - - <para> - Fortunately, HTTP supports an alternative (and more effective) caching mechanism: the <link xlink:href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag"><literal>ETag</literal></link> response header. The value of the <literal>ETag</literal> 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 <literal>If-None-Match</literal> header. If the ETag value is unchanged, then the server does not need to resend the content. - </para> - - <para> - As of NixOS 19.09, the nginx package in Nixpkgs is patched such that when nginx serves a file out of <filename>/nix/store</filename>, the hash in the store path is used as the <literal>ETag</literal> 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. - </para> - </section> -</section> |