nod#

A simple daemon that collects Nix build and substitution statistics using structured JSON logs.

requirements#

• Nix 2.30 or later (json-log-path support)

building#

cargo build --release

usage#

Start the daemon:

nod daemon

Point Nix at the socket in nix.conf:

json-log-path = /run/user/1000/nod/nod.sock

Then use Nix normally. View accumulated stats with:

nod stats          # all time
nod stats -d 7     # last 7 days
nod stats -m 3     # last 3 months
nod stats -y 1     # last year
nod clean          # reset the database

configuration#

Both directories are created automatically. The socket path in nix.conf must match --socket.

how?#

Nix 2.30 added json-log-path, which writes a stream of structured activity events (start/result/stop) to a file or Unix socket while a build runs. nod listens on that socket, tracks in-flight activities by ID, and on each stop event inserts a completed row into a local SQLite database. nod stats queries that database through the daemon.

Relevant Nix source: logging.hh