Function FetchLogs

pkg/logging/journald_logger.go:163–194

Exec's `journalctl` with the provided arguments and hooks it up to the given stdout/stderr streams.

(stdout, stderr io.Writer, journalctlArgs []string, stopChannel chan os.Signal)

// Exec's `journalctl` with the provided arguments and hooks it up
// to the given stdout/stderr streams.
func FetchLogs(stdout, stderr io.Writer, journalctlArgs []string, stopChannel chan os.Signal) error {
	journalctl, err := exec.LookPath("journalctl")
	if err != nil {
		return fmt.Errorf("could not find `journalctl` executable in PATH: %w", err)
	}

	cmd := exec.Command(journalctl, journalctlArgs...)
	cmd.Stdout = stdout
	cmd.Stderr = stderr

	if err := cmd.Start(); err != nil {
		return fmt.Errorf("failed to start journalctl command with args %#v: %w", journalctlArgs, err)
	}

	// Setup killing goroutine:
	killed := false
	go func() {
		<-stopChannel
		killed = true
		log.L.Debugf("killing journalctl logs process with PID: %#v", cmd.Process.Pid)
		cmd.Process.Kill()
	}()

	err = cmd.Wait()
	if exitError, ok := err.(*exec.ExitError); ok {
		if !killed && exitError.ExitCode() != 0 {
			return fmt.Errorf("journalctl command exited with non-zero exit code (%d): %w", exitError.ExitCode(), exitError)
		}
	}

	return nil
}

// Formats command line arguments for `journalctl` with the provided log viewing options and
// exec's and redirects `journalctl`s outputs to the provided io.Writers.