Extend libvirt-guests to shutdown only persistent VMs

At the moment, there is no configuration option for the libvirt-guests
service that allows users to define that only persistent virtual machines
should be shutdown on host shutdown.

Currently, the service config allows to choose between two ON_SHUTDOWN
actions that are executed on running virtual machines when the host goes
down: shutdown, suspend.
The ON_SHUTDOWN action should be orthogonal to the type of the virtual
machine. However, the existing implementation, does not suspend
transient virtual machines.
This is the matrix of actions that is executed on virtual machines based
on the configured ON_SHUTDOWN action and the type of a virtual machine.

         | persistent | transient
shutdown | shutdown   | shutdown (what we want to change)
suspend  | suspend    | nothing

Add config option PERSISTENT_ONLY to libvirt-guests config that allows
users to define if the ON_SHUTDOWN action should be applied only on
persistent virtual machines. PERSISTENT_ONLY can be set to true, false,
default. The default option will implement the already existing logic.

Case 1: PERSISTENT_ONLY=default
         | persistent | transient
shutdown | shutdown   | shutdown
suspend  | suspend    | nothing

Case 2: PERSISTENT_ONLY=true
         | persistent | transient
shutdown | shutdown   | nothing
suspend  | suspend    | nothing

Case 3: PERSISTENT_ONLY=false
         | persistent | transient
shutdown | shutdown   | shutdown
suspend  | suspend    | suspend

Signed-off-by: Benjamin Taubmann <benjamin.taubmann@nutanix.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>

docs/manpages/libvirt-guests.rst

@@ -113,6 +113,28 @@ The following variables are supported:
   this requires guest agent with support for time synchronization
   running in the guest. By default, this functionality is turned off.
 
+- PERSISTENT_ONLY=default
+
+  Defines what type of guest virtual machine ON_SHUTDOWN action is applied to
+
+  * default
+
+    This implements the already existing default behavior.
+    If ON_SHUTDOWN action is shutdown, transient and persistent guest virtual
+    machines are asked to shutdown.
+    If ON_SHUTDOWN action is suspend, only persistent guest virtual machines
+    are asked to suspend.
+
+  * true
+
+    ON_SHUTDOWN action is executed only on persistent guest virtual machines.
+    Transient guest virtual machines are not affected.
+
+  * false
+
+    ON_SHUTDOWN action is executed on persistent and transient guest virtual
+    machines.
+
 
 BUGS
 ====

tools/libvirt-guests.sh.in

@@ -38,6 +38,7 @@ PARALLEL_SHUTDOWN=0
 START_DELAY=0
 BYPASS_CACHE=0
 SYNC_TIME=0
+PERSISTENT_ONLY="default"
 
 test -f "$initconfdir"/libvirt-guests &&
     . "$initconfdir"/libvirt-guests
@@ -438,14 +439,16 @@ shutdown_guests_parallel()
 # stop
 # Shutdown or save guests on the configured uris
 stop() {
-    local suspending="true"
     local uri=
+    local action="suspend"
+    local persistent_only="default"
+
 
     # last stop was not followed by start
     [ -f "$LISTFILE" ] && return 0
 
     if [ "x$ON_SHUTDOWN" = xshutdown ]; then
-        suspending="false"
+        action="shutdown"
         if [ $SHUTDOWN_TIMEOUT -lt 0 ]; then
             gettext "SHUTDOWN_TIMEOUT must be equal or greater than 0"
             echo
@@ -454,6 +457,22 @@ stop() {
         fi
     fi
 
+    case "x$PERSISTENT_ONLY" in
+        xtrue)
+            persistent_only="true"
+            ;;
+        xfalse)
+            persistent_only="false"
+            ;;
+        *)
+            if [ "x$action" = xshutdown ]; then
+                persistent_only="false"
+            elif [ "x$action" = xsuspend ]; then
+                persistent_only="true"
+            fi
+            ;;
+    esac
+
     : >"$LISTFILE"
     set -f
     for uri in $URIS; do
@@ -478,7 +497,7 @@ stop() {
             echo
         fi
 
-        if "$suspending"; then
+        if "$persistent_only"; then
             local transient="$(list_guests "$uri" "--transient")"
             if [ $? -eq 0 ]; then
                 local empty="true"
@@ -486,7 +505,11 @@ stop() {
 
                 for uuid in $transient; do
                     if "$empty"; then
-                        eval_gettext "Not suspending transient guests on URI: \$uri: "
+                        if [ "x$action" = xsuspend ]; then
+                            eval_gettext "Not suspending transient guests on URI: \$uri: "
+                        else
+                            eval_gettext "Not shutting down transient guests on URI: \$uri: "
+                        fi
                         empty="false"
                     else
                         printf ", "
@@ -520,19 +543,19 @@ stop() {
 
     if [ -s "$LISTFILE" ]; then
         while read uri list; do
-            if "$suspending"; then
+            if [ "x$action" = xsuspend ]; then
                 eval_gettext "Suspending guests on \$uri URI..."; echo
             else
                 eval_gettext "Shutting down guests on \$uri URI..."; echo
             fi
 
             if [ "$PARALLEL_SHUTDOWN" -gt 1 ] &&
-               ! "$suspending"; then
+                [ "x$action" = xshutdown ]; then
                 shutdown_guests_parallel "$uri" "$list"
             else
                 local guest=
                 for guest in $list; do
-                    if "$suspending"; then
+                    if [ "x$action" = xsuspend ]; then
                         suspend_guest "$uri" "$guest"
                     else
                         shutdown_guest "$uri" "$guest"