Files
zero/internal/daemon/socket.go
KRATOS 135e3c5657 feat(daemon): zero daemon — worker pool + session supervisor over a local control socket (#203)
* feat(daemon): add `zero daemon` — worker pool + session supervisor over a local control socket

Adds internal/daemon + `zero daemon start|stop|status|run|attach`: a long-running
local service that supervises a pool of headless `zero exec` workers and routes
multiple agent sessions to them over an owner-only Unix-domain control socket.
Additive — interactive and one-shot exec are unchanged.

Reuses zero's building blocks:
- internal/background: ConfigureChildProcessGroup (process-group setup) +
  TerminateProcess (cross-platform terminate) for worker kill/drain. The pool
  does its own os/exec and uses background only for those helpers.
- internal/streamjson: the worker speaks stream-json on stdout; the daemon
  forwards those lines to clients.
- internal/cli exec: a worker is `zero exec --output-format stream-json`.

Pieces (reimplemented in Go from a reference daemon):
- protocol.go: framed control codec — 4-byte BE length + 1 kind byte, 1 MiB cap,
  JSON control messages, version negotiation.
- pool.go + backoff.go: bounded worker pool — at-least-once dispatch with
  exponential backoff+jitter retry capped by MaxAttempts, EXIT_TEMPFAIL(75)/
  EXIT_PERMANENT(76) handling, graceful drain + kill-timeout. zero's exec is
  one-shot, so workers are on-demand (one session per worker = the lease), not
  warm long-lived slots (a persistent worker mode is a follow-up).
- session.go: SessionManager — sessionID->worker routing, lease (one active
  request per worker), queue when the pool is full, per-session output buffer for
  attach + metrics.
- server.go + lock.go + socket.go + paths.go: single-instance PID-file lock with
  stale-lock (dead-PID) recovery, status file, owner-only socket, accept loop;
  cleans up lock/socket/status on exit.
- launcher.go: production worker launcher. client.go: control-socket client.

Security model:
- Control socket is LOCAL-ONLY (AF_UNIX loopback file, never a TCP port) and
  owner-only: socket 0600 + parent dir 0700 on POSIX (Windows relies on the
  per-user profile ACL; a dedicated pipe ACL is a follow-up).
- Workers stay sandboxed: the launcher SCRUBS the sandbox re-entrancy markers
  (ZERO_SANDBOXED / ZERO_SANDBOX_BACKEND) from each worker's env so the worker
  re-establishes its OWN sandbox instead of inheriting a pass-through plan, while
  propagating the rest of the policy config/env. The daemon never bypasses the
  sandbox.
- Control frames over the 1 MiB cap are rejected before allocation.

Robustness: a crashed worker never takes down the daemon (backoff+jitter retry,
MaxAttempts cap, EXIT_PERMANENT stops retry); drain gives a grace window then
force-kills stragglers; a stale lock from an unclean exit is reclaimed.

Out of scope (follow-up): remote session-linking; warm pre-spawned persistent
workers; Windows named-pipe ACL.

Tests: protocol round-trip + oversize/unknown-kind rejection; backoff bounds;
pool spawn/retry-backoff/permanent/cap/queue/drain; session lease/route/queue/
attach; lock single-instance + stale recovery; launcher env-scrub (incl. an
end-to-end check that the spawned worker process receives scrubbed env); server
e2e start->run->stream-json->status->attach->stop with a fake worker; CLI
usage/validation/not-running paths. Live-verified start/status/stop (0600 socket,
0700 dir, file cleanup). Platform files behind explicit //go:build tags.

* daemon: address review — help listing, extra-arg rejection, lock write error, bounded sessions

- cli/app.go: list `daemon` in `zero --help` so the command is discoverable.
- cli/daemon: `stop`/`status` reject extra arguments; `attach` rejects more than
  one session id (fail fast on typos instead of silently ignoring tokens).
- daemon/lock: check the PID fmt.Fprintf error — a partial/failed write would
  leave a malformed lock file that another process reads as stale and wrongly
  reclaims, breaking the single-instance guarantee; on write failure remove the
  file and return the error.
- daemon/session: bound the registry with MaxSessions (default 256) — evict the
  oldest FINISHED sessions once past the cap so a long-running daemon doesn't
  accumulate sessions without limit; running/queued sessions are never evicted, so
  attach-after-finish for recent sessions is preserved.

Tests: CLI extra-arg rejection; finished-over-cap eviction + running-never-evicted.
Gates: gofmt, vet, build, test (incl -race), staticcheck (no new), govulncheck (0),
deadcode (no new), GOOS=linux+windows cross-compile.
2026-06-14 22:16:37 +05:30

28 lines
926 B
Go

package daemon
import (
"fmt"
"os"
"path/filepath"
)
// maxUnixSocketPath bounds the socket path to the smallest platform sun_path
// limit so we surface a clear error instead of a cryptic bind failure. macOS
// allows 104 bytes incl. the NUL (so 103 chars); Linux allows 108. 103 is the
// safe cross-platform ceiling.
const maxUnixSocketPath = 103
// secureSocketParent creates the socket's parent directory owner-only (0700 on
// POSIX; on Windows the per-user profile directory is already ACL-restricted).
func secureSocketParent(socketPath string) error {
return os.MkdirAll(filepath.Dir(socketPath), 0o700)
}
// checkSocketPathLength rejects an over-long unix socket path before bind.
func checkSocketPathLength(socketPath string) error {
if len(socketPath) > maxUnixSocketPath {
return fmt.Errorf("daemon: socket path too long (%d > %d): %s", len(socketPath), maxUnixSocketPath, socketPath)
}
return nil
}