Daemon Supervisor

The daemon supervisor manages component lifecycles within a long-running Zeph process. It monitors registered components (gateway, scheduler, A2A server) for unexpected exits and tracks restart counts.

Feature Flag

Enable with --features daemon at build time:

cargo build --release --features daemon

Configuration

Add the [daemon] section to config/default.toml:

[daemon]
enabled = true
pid_file = "~/.zeph/zeph.pid"
health_interval_secs = 30
max_restart_backoff_secs = 60

PID File

The daemon writes its process ID to pid_file on startup. This file is used to detect running instances and to send stop signals. Tilde (~) expands to $HOME. The parent directory is created automatically if it does not exist.

Component Lifecycle

Each registered component is wrapped in a ComponentHandle that tracks:

name – human-readable identifier (e.g., "gateway", "scheduler")
status – Running, Failed(reason), or Stopped
restart_count – number of unexpected exits detected

The supervisor polls all components at health_interval_secs intervals. When a running component’s task handle reports completion (unexpected exit), the supervisor marks it as Failed and increments its restart counter.

Shutdown

The supervisor listens on the global shutdown signal (watch::Receiver<bool>). When the signal fires, the health loop exits and all component handles are dropped.

PID File Utilities

The daemon module provides three standalone functions for PID file management:

Function	Description
`write_pid_file(path)`	Write current process ID to file
`read_pid_file(path)`	Read PID from file
`remove_pid_file(path)`	Remove PID file (no-op if missing)

Keyboard shortcuts