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diff --git a/doc/builders/images/binarycache.section.md b/doc/builders/images/binarycache.section.md new file mode 100644 index 0000000000000..71dc26311cf02 --- /dev/null +++ b/doc/builders/images/binarycache.section.md @@ -0,0 +1,49 @@ +# pkgs.mkBinaryCache {#sec-pkgs-binary-cache} + +`pkgs.mkBinaryCache` is a function for creating Nix flat-file binary caches. Such a cache exists as a directory on disk, and can be used as a Nix substituter by passing `--substituter file:///path/to/cache` to Nix commands. + +Nix packages are most commonly shared between machines using [HTTP, SSH, or S3](https://nixos.org/manual/nix/stable/package-management/sharing-packages.html), but a flat-file binary cache can still be useful in some situations. For example, you can copy it directly to another machine, or make it available on a network file system. It can also be a convenient way to make some Nix packages available inside a container via bind-mounting. + +Note that this function is meant for advanced use-cases. The more idiomatic way to work with flat-file binary caches is via the [nix-copy-closure](https://nixos.org/manual/nix/stable/command-ref/nix-copy-closure.html) command. You may also want to consider [dockerTools](#sec-pkgs-dockerTools) for your containerization needs. + +## Example + +The following derivation will construct a flat-file binary cache containing the closure of `hello`. + +```nix +mkBinaryCache { + rootPaths = [hello]; +} +``` + +- `rootPaths` specifies a list of root derivations. The transitive closure of these derivations' outputs will be copied into the cache. + +Here's an example of building and using the cache. + +Build the cache on one machine, `host1`: + +```shellSession +nix-build -E 'with import <nixpkgs> {}; mkBinaryCache { rootPaths = [hello]; }' +``` + +```shellSession +/nix/store/cc0562q828rnjqjyfj23d5q162gb424g-binary-cache +``` + +Copy the resulting directory to the other machine, `host2`: + +```shellSession +scp result host2:/tmp/hello-cache +``` + +Build the derivation using the flat-file binary cache on the other machine, `host2`: +```shellSession +nix-build -A hello '<nixpkgs>' \ + --option require-sigs false \ + --option trusted-substituters file:///tmp/hello-cache \ + --option substituters file:///tmp/hello-cache +``` + +```shellSession +/nix/store/gl5a41azbpsadfkfmbilh9yk40dh5dl0-hello-2.12.1 +``` |