Add keepalived check multiple processes script

This patch adds script that can track for multiple
processes in process table and fail in case some of them
is dead.

The script is located on
system.keepalived.cluster.vrrp_scripts.check_multiple_processes

Example:
classes:
 - system.keepalived.cluster.vrrp_scripts.check_multiple_processes
parameters:
  _param:
    keepalived_vrrp_script_check_multiple_processes: 'nginx apache2'

Change-Id: Ic185e68737ba9601dfb1f9b809a24b946449b6a8
Related-Prod: PROD-25015
diff --git a/keepalived/cluster/vrrp_scripts/check_multiple_processes.yml b/keepalived/cluster/vrrp_scripts/check_multiple_processes.yml
new file mode 100644
index 0000000..bfad21e
--- /dev/null
+++ b/keepalived/cluster/vrrp_scripts/check_multiple_processes.yml
@@ -0,0 +1,17 @@
+parameters:
+  keepalived:
+    cluster:
+      vrrp_scripts:
+        multiple_processes:
+          args: ${_param:keepalived_vrrp_script_check_multiple_processes}
+          content: |
+            #!/bin/sh
+            set -o errexit
+            for process in $@; do
+              if ! pidof $process; then
+                exit 1
+              fi
+            done
+          interval: 10
+          rise: 1
+          fall: 1