Starting the daemon

vendor/bin/opcua-session-manager is the launcher. Run it in the foreground and you have the daemon. In production you wrap it in systemd or supervisor — same binary, no special "daemon mode".

Foreground

vendor/bin/opcua-session-manager

Output:

[2026-05-15 08:30:00] [INFO] OPC UA Session Manager started on unix:///tmp/opcua-session-manager.sock
[2026-05-15 08:30:00] [INFO] Timeout: 600s, Cleanup interval: 30s, Max sessions: 100
[2026-05-15 08:30:00] [INFO] Socket permissions: 600

The actual StreamLogger format is [YYYY-MM-DD HH:MM:SS] [LEVEL] message — the level is uppercased and the socket value includes its full URI (unix://... or tcp://...), with {...} context placeholders interpolated into the message itself.

The daemon stays in the foreground until Ctrl-C or SIGTERM. It binds its IPC listener, writes a PID file next to the socket, and enters the ReactPHP event loop.

The PID file

The daemon writes a PID file alongside its endpoint:

• Unix socket: /tmp/opcua-session-manager.sock.pid
• TCP loopback: /tmp/opcua-session-manager-tcp_127.0.0.1_9990.pid

On startup the daemon checks for an existing PID file. If the file exists and the recorded PID is still alive, the launch fails — there is already a daemon on that endpoint. To restart cleanly, stop the running daemon first (SIGTERM is enough; the daemon removes its own PID file on shutdown).

Bind on a non-default endpoint

# Unix socket at a custom path
vendor/bin/opcua-session-manager --socket /var/run/opcua/sessions.sock

# TCP loopback on a chosen port
vendor/bin/opcua-session-manager --socket tcp://127.0.0.1:9991

# Scheme-less path is treated as a Unix socket (backwards-compat)
vendor/bin/opcua-session-manager --socket /opt/opcua/sessions.sock

The --socket flag accepts any of:

Non-loopback hosts (tcp://0.0.0.0:9990, tcp://10.x.x.x:9990) are rejected at startup with a RuntimeException. The daemon refuses to expose itself to the network without an explicit transport layer (TLS, SSH tunnel). See Daemon · Transports.

The socket path length limit

Unix-domain socket paths are capped by the kernel — 108 bytes on Linux, 104 on Darwin. The daemon validates the path length before binding:

Unix socket path is too long: 132 bytes, but the Linux kernel limits sun_path to 108 bytes (usable 107). The kernel silently truncates longer paths, which breaks chmod() and reconnect. Set OPCUA_SOCKET_PATH (or pass --socket) to a shorter path, e.g. /tmp/opcua-session.sock. Got: /very/deeply/nested/path/that/exceeds/the/cap.sock

A path that exceeds the cap previously surfaced as a confusing chmod(): No such file or directory after a silently truncated bind. The explicit check (added in v4.3.1) replaces that with the message above.

Shutting down

Send SIGTERM (or SIGINT from the keyboard). The daemon:

1. 01

   Stops accepting new IPC connections.

   The listener is unbound; in-flight requests are allowed to complete.

2. 02

   Drains the OPC UA sessions.

   Each active session sends CloseSession + CloseSecureChannel to its server. Failures here are logged but do not block shutdown.

3. 03

   Removes the PID file.

   Releases the lock for the next start.

4. 04

   Exits.

SIGKILL skips all of that — the PID file and the Unix socket are left on disk, the next start will refuse to launch until they are cleaned up. Always prefer SIGTERM.

What "running" means

The daemon is running when all of the following are true:

• The PID in its PID file is alive.
• The IPC endpoint accepts connections.
• A ping command returns {"success": true, "data": {"status": "ok", ...}}.

The first two are infrastructure checks; the third is the canonical healthcheck — see Recipes · Healthcheck and monitoring.

Programmatic embedding

The daemon is a regular PHP class — SessionManagerDaemon — and nothing forces you to use the binary. If you have a host process that wants to manage the lifecycle itself (a Symfony Console command, a long-running worker, a NativePHP shell), construct the daemon directly:

use PhpOpcua\SessionManager\Daemon\SessionManagerDaemon;
use PhpOpcua\Client\Cache\InMemoryCache;
use Psr\Log\NullLogger;

$daemon = new SessionManagerDaemon(
    socketPath: '/tmp/my-opcua.sock',
    timeout: 600,
    cleanupInterval: 30,
    authToken: null,
    maxSessions: 100,
    socketMode: 0600,
    allowedCertDirs: null,
    logger: new NullLogger(),
    clientCache: new InMemoryCache(300),
);

$daemon->run();   // blocks until SIGTERM / SIGINT

Constructor arguments mirror the CLI options one-to-one (see Daemon · Configuration). run() blocks the caller until shutdown — wrap it in your own process supervision if you need finer control.