pping: Change single pping-service into generic template

Replace the systemd unit files that needed to be modified for a
specific interface with template files. The template files allows one
to instansiate a service for any interface (by running systemctl
start pping@<interface>.service), and multiple interfaces can be
monitored at once.

Each instance maintains a separtate "log" of data at
/sys/var/log/pping/<interface>/pping.<interface>.json which is rotated
one per minute (see the rotate-pping@.timer file) and placed in daily
subfolders.

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>

pping/scripts/rotate-pping-output.sh

@@ -2,6 +2,7 @@
 
 MAX_WAIT_ITER=10
 pping_path=${1:-"/var/log/pping/pping.out.json"}
+instance=$2 # pping service instance to reload
 
 pping_folder=$(dirname "$pping_path")
 pping_file=$(basename "$pping_path")
@@ -21,11 +22,12 @@ if ! mv "$pping_path" "$newplace"; then
     exit 1
 fi
 
-# Tell ePPing to reopen file
-if systemctl is-active --quiet pping.service; then
-    systemctl reload pping.service
+
+if [[ -n "$instance" ]] && systemctl is-active --quiet "pping@$instance.service"; then
+    systemctl reload "pping@$instance.service"
 fi
 
+# Compress the old file (once ePPing has stopped writing to it)
 if [[ -f "$newplace" ]]; then
     for (( i = 0; i < MAX_WAIT_ITER; i++)); do
 	if fuser -s "$newplace"; then