config: add process.shutdown.parent_only option.

Defaults to false, in which case the shutdown signal is sent to the
running process' process group. If true, the shutdown signal is only
sent to the running process itself.

Signed-off-by: Etienne Wodey <etienne.wodey@aqt.eu>

README.md

@@ -245,17 +245,20 @@ nginx:
     command: "docker stop nginx_test"
     timeout_seconds: 10 # default 10
     signal: 15 # default 15, but only if the 'command' is not defined or empty
+    parent_only: no  # default no. If yes, only signal the running process instead of its whole process group
 ```
 
-`shutdown` is optional and can be omitted. The default behavior in this case: `SIGTERM` is issued to the running process.
+`shutdown` is optional and can be omitted. The default behavior in this case: `SIGTERM` is issued to the process group of the running process.
 
-In case only `shutdown.signal` is defined `[1..31] ` the running process will be terminated with its value.
+In case only `shutdown.signal` is defined `[1..31] ` the running process group will be terminated with its value.
+
+If `shutdown.parent_only` is yes, the signal is only sent to the running process and not to the whole process group.
 
 In case the `shutdown.command` is defined:
 
 1. The `shutdown.command` is executed with all the Environment Variables of the primary process
 2. Wait for `shutdown.timeout_seconds` for its completion (if not defined wait for 10 seconds)
-3. In case of timeout, the process will receive the `SIGKILL` signal
+3. In case of timeout, the process group will receive the `SIGKILL` signal (irrespective of the `shutdown.parent_only` option).
 
 ##### Background (detached) Processes
 

src/app/process.go

@@ -248,7 +248,8 @@ func (p *Process) shutDown() error {
 	if isStringDefined(p.procConf.ShutDownParams.ShutDownCommand) {
 		return p.doConfiguredStop(p.procConf.ShutDownParams)
 	}
-	return p.stop(p.procConf.ShutDownParams.Signal)
+
+	return p.stop(p.procConf.ShutDownParams.Signal, p.procConf.ShutDownParams.ParentOnly)
 }
 
 func (p *Process) doConfiguredStop(params types.ShutDownParams) error {
@@ -267,7 +268,7 @@ func (p *Process) doConfiguredStop(params types.ShutDownParams) error {
 	if err := cmd.Run(); err != nil {
 		// the process termination timedout and it will be killed
 		log.Error().Msgf("terminating %s with timeout %d failed - %s", p.getName(), timeout, err.Error())
-		return p.stop(int(syscall.SIGKILL))
+		return p.stop(int(syscall.SIGKILL), false)
 	}
 	return nil
 }

src/app/process_unix.go

@@ -3,6 +3,7 @@
 package app
 
 import (
+	"github.com/rs/zerolog/log"
 	"syscall"
 )
 
@@ -11,17 +12,30 @@ const (
 	max_sig = 31
 )
 
-func (p *Process) stop(sig int) error {
+func (p *Process) stop(sig int, parentOnly bool) error {
 	if p.command == nil {
 		return nil
 	}
 	if sig < min_sig || sig > max_sig {
 		sig = int(syscall.SIGTERM)
 	}
+
+	log.
+		Debug().
+		Int("pid", p.command.Process.Pid).
+		Int("signal", sig).
+		Bool("parentOnly", parentOnly).
+		Msg("Stop Unix process.")
+
+	if parentOnly {
+		return syscall.Kill(p.command.Process.Pid, syscall.Signal(sig))
+	}
+
 	pgid, err := syscall.Getpgid(p.command.Process.Pid)
 	if err == nil {
 		return syscall.Kill(-pgid, syscall.Signal(sig))
 	}
+
 	return err
 }
 

src/app/process_windows.go

@@ -5,7 +5,7 @@ import (
 	"strconv"
 )
 
-func (p *Process) stop(sig int) error {
+func (p *Process) stop(sig int, _parentOnly bool) error {
 	//p.command.Process.Kill()
 	kill := exec.Command("TASKKILL", "/T", "/F", "/PID", strconv.Itoa(p.command.Process.Pid))
 	return kill.Run()

src/types/process.go

@@ -91,6 +91,7 @@ type ShutDownParams struct {
 	ShutDownCommand string `yaml:"command,omitempty"`
 	ShutDownTimeout int    `yaml:"timeout_seconds,omitempty"`
 	Signal          int    `yaml:"signal,omitempty"`
+	ParentOnly      bool   `yaml:"parent_only,omitempty"`
 }
 
 const (