README.md

Asynchronous post-build-hook

this hook queues up store paths on a unix domain socket and then spawns a service to actually push the store path to the cache through socket activation

works on MacOS and Linux

nix-copy.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
	<dict>
		<key>Label</key>
		<string>nix-post-build-hook</string>
		<key>KeepAlive</key>
		<false/>
		<key>RunAtLoad</key>
		<true/>
		<key>Program></key>
		<string>xargs</string>
		<key>ProgramArguments</key>
		<array>
			<string>--verbose</string>
			<string>--no-run-if-empty</string>
			<string>nix</string>
			<string>copy</string>
			<string>--to</string>
			<string>s3://my-bucket</string>
		</array>
		<key>StandardErrorPath</key>
		<string>/var/log/nix-post-build-hook.log</string>
		<key>Sockets</key>
		<dict>
			<key>Listeners</key>
			<dict>
				<key>SocketType</key>
				<string>stream</string>
				<key>SockPathName</key>
				<string>/var/run/nix-post-build-hook.sock</string>
				<key>inetdCompatibility</key>
				<dict>
					<key>Wait</key>
					<false/>
				</dict>
			</dict>
		</dict>
	</dict>
</plist>

nix-copy.socket

[Socket]
ListenStream=%t/%N.sock
SocketMode=0600
Accept=yes

[email protected]

[Service]
LoadCredential=signing-key
Environment=NIX_STORE_URI=s3://my-bucket?secret-key=%d/signing-key&compression=zstd&parallel-compression=true
StandardInput=socket
ExecSearchPath=/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin
ExecStart=xargs --no-run-if-empty --verbose nix copy --to $NIX_STORE_URI
DynamicUser=yes

nix.conf

post-build-hook = socat EXEC:'printenv OUT_PATHS' UNIX-CONNECT:/var/run/nix-copy.sock