159646787a
Introduces a `.overrideDeps` attribute with which additional tools can be supplied. This works like `.override` in nixpkgs. Change-Id: I69a009b51f7f073a2d030eda5e3b5310e0f8e883 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8491 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
91 lines
2.7 KiB
Nix
91 lines
2.7 KiB
Nix
# Helper function to synthesize a directory of "lazy-built" binaries
|
|
# that can be added to $PATH inside of a repository.
|
|
#
|
|
# Using this, a Nix shell environment in some repository can contain
|
|
# several slow-to-build commands without blowing up evaluation and
|
|
# build time whenever the shell is loaded.
|
|
#
|
|
# Note that the generated script is deliberately impure to speed up
|
|
# evaluation, and expects both `git` and `nix-build` to exist in the
|
|
# user's $PATH. If required, this can be done in the shell
|
|
# configuration invoking this function.
|
|
{ pkgs, lib, ... }:
|
|
|
|
let
|
|
inherit (builtins) attrNames attrValues mapAttrs;
|
|
inherit (lib) fix concatStringsSep;
|
|
|
|
# Create the case statement for a command invocations, optionally
|
|
# overriding the `TARGET_TOOL` variable.
|
|
invoke = name: { attr, cmd ? null }: ''
|
|
${name})
|
|
attr="${attr}"
|
|
${if cmd != null then "TARGET_TOOL=\"${cmd}\"\n;;" else ";;"}
|
|
'';
|
|
|
|
# Create command to symlink to the dispatch script for each tool.
|
|
link = name: "ln -s $target $out/bin/${name}";
|
|
|
|
invocations = tools: concatStringsSep "\n" (attrValues (mapAttrs invoke tools));
|
|
in
|
|
fix (self:
|
|
|
|
# Attribute set of tools that should be lazily-added to the $PATH.
|
|
#
|
|
# The name of each attribute is used as the command name (on $PATH).
|
|
# It must contain the keys 'attr' (containing the Nix attribute path
|
|
# to the tool's derivation from the top-level), and may optionally
|
|
# contain the key 'cmd' to override the name of the binary inside the
|
|
# derivation.
|
|
tools:
|
|
|
|
pkgs.runCommandNoCC "lazy-dispatch"
|
|
{
|
|
passthru.overrideDeps = newTools: self (tools // newTools);
|
|
passthru.tools = tools;
|
|
|
|
text = ''
|
|
#!${pkgs.runtimeShell}
|
|
set -ue
|
|
|
|
if ! type git>/dev/null || ! type nix-build>/dev/null; then
|
|
echo "The 'git' and 'nix-build' commands must be available." >&2
|
|
exit 127
|
|
fi
|
|
|
|
readonly REPO_ROOT=$(git rev-parse --show-toplevel)
|
|
TARGET_TOOL=$(basename "$0")
|
|
|
|
case "''${TARGET_TOOL}" in
|
|
${invocations tools}
|
|
*)
|
|
echo "''${TARGET_TOOL} is currently not installed in this repository." >&2
|
|
exit 127
|
|
;;
|
|
esac
|
|
|
|
result=$(nix-build --no-out-link --attr "''${attr}" "''${REPO_ROOT}")
|
|
PATH="''${result}/bin:$PATH"
|
|
exec "''${TARGET_TOOL}" "''${@}"
|
|
'';
|
|
|
|
# Access this to get a compatible nix-shell
|
|
passthru.devShell = pkgs.mkShellNoCC {
|
|
name = "${self.name}-shell";
|
|
packages = [ self ];
|
|
};
|
|
}
|
|
''
|
|
# Write the dispatch code
|
|
target=$out/bin/__dispatch
|
|
mkdir -p "$(dirname "$target")"
|
|
echo "$text" > $target
|
|
chmod +x $target
|
|
|
|
# Add symlinks from all the tools to the dispatch
|
|
${concatStringsSep "\n" (map link (attrNames tools))}
|
|
|
|
# Check that it's working-ish
|
|
${pkgs.stdenv.shellDryRun} $target
|
|
''
|
|
)
|