.github/workflows | ||
tests | ||
default.nix | ||
flake.nix | ||
LICENSE | ||
nix-filter.svg | ||
README.md |
nix-filter - a small self-contained source filtering lib
STATUS: beta
A cool way to include only what you need.
When using nix within a project, developers often use src = ./.;
for a
project like this:
{ stdenv }:
stdenv.mkDerivation {
name = "my-project";
src = ./.;
}
This works but has an issue; on each build, nix will copy the whole project
source code into the /nix/store. Including the .git
folder and any temporary
files left over by the editor.
The main workaround is to use either builtins.fetchGit ./.
or one of the
many gitignore filter projects but this is not precise enough. If the
project README changes, it should rebuild the project. If the nix code
changes, it shouldn't rebuild the project. That's why this project exists. I
want total control.
Example usage
{ stdenv, nix-filter }:
stdenv.mkDerivation {
name = "my-project";
src = nix-filter {
root = ./.;
# If no include is passed, it will include all the paths.
include = [
# Include the "src" path relative to the root.
"src"
# Include this specific path. The path must be under the root.
./package.json
# Include all files with the .js extension
(nix-filter.matchExt "js")
];
# Works like include, but the reverse.
exclude = [
./main.js
];
};
}
How it works
nix-filter is a function that takes:
path
of typepath
: pointing to the root of the source to add to the /nix/store.name
of typestring
(optional): the name of the derivation (defaults to "source")include
of typelist(string|path|matcher)
(optional): a list of patterns to include (defaults to all).exclude
of typelist(string|path|matcher)
(options): a list of patterns to exclude (defaults to none).
The include
and exclude
take a matcher, and automatically convert the string
and path
types to a matcher.
The matcher is a function that takes a path
and type
and returns true
if
the pattern matches.
Builtin matchers
matchExt
:ext
-> returns a function that matches the given file extension.inDirectory
:directory
-> returns a function that matches a directory and any path inside of it.isDirectory
: matches all paths that are directories
Combining matchers
and
:a -> b -> c
combines the result of two matchers into a new matcher.or
:a -> b -> c
combines the result of two matchers into a new matcher.
Future development
Solve the above issue. Add more matchers.
License
Copyright (c) 2021 Numtide under the MIT.