container images typically don't have systemd, this should allow the …

…choria package to be installed on those images.

packager/templates/debian/generic/postinst

@@ -5,9 +5,15 @@ action="$1"
 if [ "$action" = configure ]; then
 	old_version="$2"
 
-	if [ -z "$old_version" ]; then
-		systemctl enable choria-server.service
-	else
-		systemctl try-restart choria-broker.service choria-server.service
-	fi
-fi
+  if command -v systemctl 2>&1 >/dev/null
+  then
+    if [ -z "$old_version" ]; then
+      systemctl enable choria-server.service
+    else
+      systemctl try-restart choria-broker.service choria-server.service
+    fi
+  else
+    echo "systemctl could not be found, skipping service start."
+    exit 0
+  fi
+fi

packager/templates/debian/generic/postrm

@@ -1,3 +1,9 @@
 #!/bin/sh
 
-systemctl daemon-reload
+if command -v systemctl 2>&1 >/dev/null
+then
+  systemctl daemon-reload
+else
+  echo "systemctl could not be found, skipping daemon reload."
+  exit 0
+fi

packager/templates/debian/generic/prerm

@@ -2,7 +2,13 @@
 
 action="$1"
 
-if [ "$action" = remove ]; then
-	systemctl --no-reload disable choria-server.service choria-broker.service
-	systemctl stop choria-server.service choria-broker.service
-fi
+if command -v systemctl 2>&1 >/dev/null
+then
+  if [ "$action" = remove ]; then
+    systemctl --no-reload disable choria-server.service choria-broker.service
+    systemctl stop choria-server.service choria-broker.service
+  fi
+else
+  echo "systemctl could not be found, skipping service disable & remove."
+  exit 0
+fi