pping: Add systemd unit files for running pping

Add some example files for setting up ePPing with systemd.
The setup creates "log" files in /var/log/pping and rotates
them every minute (appending a date at the time of rotation).

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

pping/scripts/rotate-pping-output.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+MAX_WAIT_ITER=10
+pping_path=${1:-"/var/log/pping/pping.out.json"}
+
+pping_folder=$(dirname "$pping_path")
+pping_file=$(basename "$pping_path")
+
+if [[ ! -f "$pping_path" ]]; then
+    # Nothing to rotate
+    exit 0
+fi
+
+dailyfolder="$pping_folder/$(date -Idate)"
+if ! mkdir -p "$dailyfolder"; then
+    exit 1
+fi
+
+newplace="$dailyfolder/$pping_file.$(date -Iseconds)"
+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
+fi
+
+if [[ -f "$newplace" ]]; then
+    for (( i = 0; i < MAX_WAIT_ITER; i++)); do
+	if fuser -s "$newplace"; then
+	    sleep 1
+	else
+	    gzip "$newplace"
+	    exit $?
+	fi
+    done
+fi
+
+echo "Timed out waiting for $newplace to become unused, unable to compress it" 1>&2
+exit 1