b3df7f8a3d
Document the nix-cache-info file format used by binary caches, including the StoreDir, WantMassQuery, and Priority fields, their behavior, and links to related store options.
50 lines
1.7 KiB
Markdown
50 lines
1.7 KiB
Markdown
# Serving a Nix store via HTTP
|
|
|
|
You can easily share the Nix store of a machine via HTTP. This allows
|
|
other machines to fetch store paths from that machine to speed up
|
|
installations. It uses the same *binary cache* mechanism that Nix
|
|
usually uses to fetch pre-built binaries from <https://cache.nixos.org>.
|
|
|
|
The daemon that handles binary cache requests via HTTP, `nix-serve`, is
|
|
not part of the Nix distribution, but you can install it from Nixpkgs:
|
|
|
|
```console
|
|
$ nix-env --install --attr nixpkgs.nix-serve
|
|
```
|
|
|
|
You can then start the server, listening for HTTP connections on
|
|
whatever port you like:
|
|
|
|
```console
|
|
$ nix-serve -p 8080
|
|
```
|
|
|
|
To check whether it works, try fetching the [`nix-cache-info`](@docroot@/protocols/nix-cache-info.md) file on the client:
|
|
|
|
```console
|
|
$ curl http://avalon:8080/nix-cache-info
|
|
StoreDir: /nix/store
|
|
WantMassQuery: 1
|
|
Priority: 30
|
|
```
|
|
|
|
When writing to a binary cache (e.g., with [`nix copy`](@docroot@/command-ref/new-cli/nix3-copy.md)), Nix creates [`nix-cache-info`](@docroot@/protocols/nix-cache-info.md) automatically if it doesn't exist.
|
|
|
|
On the client side, you can tell Nix to use your binary cache using
|
|
`--substituters`, e.g.:
|
|
|
|
```console
|
|
$ nix-env --install --attr nixpkgs.firefox --substituters http://avalon:8080/
|
|
```
|
|
|
|
The option `substituters` tells Nix to use this binary cache in
|
|
addition to your default caches, such as <https://cache.nixos.org>.
|
|
Thus, for any path in the closure of Firefox, Nix will first check if
|
|
the path is available on the server `avalon` or another binary caches.
|
|
If not, it will fall back to building from source.
|
|
|
|
You can also tell Nix to always use your binary cache by adding a line
|
|
to the `nix.conf` configuration file like this:
|
|
|
|
substituters = http://avalon:8080/ https://cache.nixos.org/
|