make it possible to install additional packages at runtime and not only during build

Signed-off-by: Felix Bartels <felix@host-consultants.de>

core/start-service.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
 
+ADDITIONAL_KOPANO_PACKAGES=${ADDITIONAL_KOPANO_PACKAGES:-""}
+
 set -eu # unset variables are errors & non-zero return values exit the whole script
 
 if [ ! -e /kopano/$SERVICE_TO_START.py ]
@@ -8,6 +10,13 @@ then
     exit 1
 fi
 
+[ ! -z "$ADDITIONAL_KOPANO_PACKAGES" ] && apt update
+[ ! -z "$ADDITIONAL_KOPANO_PACKAGES" ] && for installpkg in "$ADDITIONAL_KOPANO_PACKAGES"; do
+	if [ $(dpkg-query -W -f='${Status}' $installpkg 2>/dev/null | grep -c "ok installed") -eq 0 ]; then
+		apt --assume-yes install $installpkg;
+	fi
+done
+
 mkdir -p /kopano/data/attachments /tmp/$SERVICE_TO_START /var/run/kopano
 
 echo "Configure core service '$SERVICE_TO_START'" | ts