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Co-Authored-By: Virgil <virgil@lethean.io>
98 lines
2.4 KiB
Markdown
98 lines
2.4 KiB
Markdown
---
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title: Daemon Mode
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description: Daemon process management, PID files, health checks, and execution modes.
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---
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# Daemon Mode
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The framework provides execution mode detection and signal handling for daemon processes.
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## Execution Modes
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The framework auto-detects the execution environment:
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```go
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mode := cli.DetectMode()
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```
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| Mode | Condition | Behaviour |
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|------|-----------|-----------|
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| `ModeInteractive` | TTY attached | Colours enabled, spinners active |
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| `ModePipe` | stdout piped | Colours disabled, plain output |
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| `ModeDaemon` | `CORE_DAEMON=1` env var | Log-only output |
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Helper functions:
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```go
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cli.IsTTY() // stdout is a terminal?
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cli.IsStdinTTY() // stdin is a terminal?
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cli.IsStderrTTY() // stderr is a terminal?
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```
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## Simple Daemon
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Use `cli.Context()` for cancellation-aware daemon loops:
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```go
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func runDaemon(cmd *cli.Command, args []string) error {
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ctx := cli.Context() // Cancelled on SIGINT/SIGTERM
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// ... start your work ...
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<-ctx.Done()
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return nil
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}
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```
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## Daemon Helper
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Use `cli.NewDaemon()` when you want a helper that writes a PID file and serves
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basic `/health` and `/ready` probes:
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```go
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daemon := cli.NewDaemon(cli.DaemonOptions{
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PIDFile: "/tmp/core.pid",
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HealthAddr: "127.0.0.1:8080",
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HealthCheck: func() bool {
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return true
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},
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ReadyCheck: func() bool {
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return true
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},
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})
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if err := daemon.Start(context.Background()); err != nil {
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return err
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}
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defer func() {
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_ = daemon.Stop(context.Background())
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}()
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```
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`Start()` writes the current process ID to the configured file, and `Stop()`
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removes it after shutting the probe server down.
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If you need to stop a daemon process from outside its own process tree, use
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`cli.StopPIDFile(pidFile, timeout)`. It sends `SIGTERM`, waits up to the
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timeout for exit, escalates to `SIGKILL` if needed, and removes the PID file
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after the process stops.
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## Shutdown with Timeout
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The daemon stop logic sends SIGTERM and waits up to 30 seconds. If the process has not exited by then, it sends SIGKILL and removes the PID file.
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## Signal Handling
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Signal handling is built into the CLI runtime:
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- **SIGINT/SIGTERM** cancel `cli.Context()`
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- **SIGHUP** calls the `OnReload` handler if configured:
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```go
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cli.Init(cli.Options{
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AppName: "daemon",
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OnReload: func() error {
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return reloadConfig()
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},
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})
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```
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No manual signal handling is needed in commands. Use `cli.Context()` for cancellation-aware operations.
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