7. Production

$ kzig build                 # zig build -Doptimize=ReleaseSafe
Built zig-out/bin/. Run it with `kzig start`.
$ API_KEY=… MIGRATE_ON_BOOT=true kzig start
info: migration 20261028_024358_init applied
info: listening on http://127.0.0.1:3000

kzig start runs the built binary with KZIG_ENV=production and replaces itself with it, so a supervisor's signals reach the app. The binary is all you deploy, with db/migrations beside it.

Settings

Variable	Default
PORT	3000
HOST	127.0.0.1	0.0.0.0 to accept connections from other machines (chapter 8 adds it)
KZIG_ENV	production	development or test turn on the development defaults (KZIG_ENV is read when it isn't set)
API_KEY	none in production	at least 32 characters
DB_FILE	data/bookmarks.db	its folder is created
MIGRATIONS_DIR	db/migrations
MIGRATE_ON_BOOT	false	true applies pending migrations at start; otherwise a pending one stops the boot
API_KEY_FILE, …		any setting can be read from a file instead (<NAME>_FILE), for secrets

A missing or invalid setting stops the boot with every problem listed, not the first request.

Stopping

On SIGTERM or SIGINT the app stops accepting connections, lets requests in flight finish (up to 30 s), closes idle connections, then runs each adapter's shutdown and each service's deinit in reverse order. /health/ready answers draining meanwhile, so a load balancer stops sending traffic.

Next, Docker.