Add `force-stop` support to launch script

Update the embedded launch script to support `force-stop`.

Closes gh-6223

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/java/org/springframework/boot/launchscript/SysVinitLaunchScriptIT.java

@@ -118,6 +118,14 @@ public class SysVinitLaunchScriptIT {
 				.has(coloredString(AnsiColor.YELLOW, "Not running (pidfile not found)"));
 	}
 
+	@Test
+	public void forceStopWhenStopped() throws Exception {
+		String output = doTest("force-stop-when-stopped.sh");
+		assertThat(output).contains("Status: 0");
+		assertThat(output)
+				.has(coloredString(AnsiColor.YELLOW, "Not running (pidfile not found)"));
+	}
+
 	@Test
 	public void startWhenStarted() throws Exception {
 		String output = doTest("start-when-started.sh");

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/resources/scripts/force-stop-when-stopped.sh

+source ./test-functions.sh
+install_service
+force_stop_service
+echo "Status: $?"

spring-boot-integration-tests/spring-boot-launch-script-tests/src/test/resources/scripts/test-functions.sh

@@ -21,6 +21,10 @@ stop_service() {
   service spring-boot-app stop
 }
 
+force_stop_service() {
+  service spring-boot-app force-stop
+}
+
 await_app() {
   if [ -z $1 ]
   then

spring-boot-tools/spring-boot-loader-tools/src/main/resources/org/springframework/boot/loader/tools/launch.script

@@ -203,6 +203,24 @@ do_stop() {
   return 1;
 }
 
+force_stop() {
+  [[ -f $pid_file ]] || { echoYellow "Not running (pidfile not found)"; return 0; }
+  pid=$(cat "$pid_file")
+  isRunning "$pid" || { echoYellow "Not running (process ${pid}). Removing stale pid file."; rm -f "$pid_file"; return 0; }
+  do_force_stop "$pid" "$pid_file"
+}
+
+do_force_stop() {
+  kill -9 "$1" &> /dev/null || { echoRed "Unable to kill process $1"; return 1; }
+  for i in $(seq 1 60); do
+    isRunning "$1" || { echoGreen "Stopped [$1]"; rm -f "$2"; return 0; }
+    [[ $i -eq 30 ]] && kill -9 "$1" &> /dev/null
+    sleep 1
+  done
+  echoRed "Unable to kill process $1";
+  return 1;
+}
+
 restart() {
   stop && start
 }
@@ -242,6 +260,8 @@ start)
   start "$@"; exit $?;;
 stop)
   stop "$@"; exit $?;;
+force-stop)
+  force_stop "$@"; exit $?;;
 restart)
   restart "$@"; exit $?;;
 force-reload)