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>

Author: simosund

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

pping/systemd-files/pping.service renamed to pping/systemd-files/pping@.service

@@ -1,32 +1,31 @@
-[Unit]
-Description=ePPing - Passive monitoring of network RTTs
-After=network.service
-Wants=rotate-pping.timer
-
-# Uncomment below if running with LibreQoS
-# After=lqosd.service
-
-[Service]
-# Ensure folder for saving output to exists
-ExecStartPre=/usr/bin/mkdir -p /var/log/pping
-
-# Rotate any old output first to ensure ePPing can start writing to its intended file
-ExecStartPre=/opt/bpf-examples/pping/scripts/rotate-pping-output.sh /var/log/pping/pping.out.json
-
-WorkingDirectory=/opt/bpf-examples/pping
-ExecStart=/opt/bpf-examples/pping/pping -i <interface> -l -r 10 -a 10 -F json -w /var/log/pping/pping.out.json
-
-# On systemctl reload, send a SIGHUP to ePPing which causes it to reopen its output file
-ExecReload=kill -HUP $MAINPID
-
-Restart=on-failure
-RestartSec=60
-
-# Set to whatever maximum memory footprint you can tolerate
-# Note, hard-kills the ePPing process without allowing it to clean up. Consider
-# running /scripts/cleanup-tc-progs after.
-MemoryMax=4G
-
-[Install]
-WantedBy=default.target
-
+[Unit]
+Description=ePPing - Passive monitoring of network RTTs on %i
+After=network.service
+Wants=rotate-pping@%i.timer
+
+# Uncomment below if running with LibreQoS
+# After=lqosd.service
+
+[Service]
+# Ensure folder for saving output to exists
+ExecStartPre=/usr/bin/mkdir -p /var/log/pping/%i
+
+# Rotate any old output first to ensure ePPing can start writing to its intended file
+ExecStartPre=/opt/bpf-examples/pping/scripts/rotate-pping-output.sh /var/log/pping/%i/pping.%i.json
+
+WorkingDirectory=/opt/bpf-examples/pping
+ExecStart=/opt/bpf-examples/pping/pping -i %i -l -r 10 -a 10 -F json -w /var/log/pping/%i/pping.%i.json
+
+# On systemctl reload, send a SIGHUP to ePPing which causes it to reopen its output file
+ExecReload=kill -HUP $MAINPID
+
+Restart=on-failure
+RestartSec=60
+
+# Set to whatever maximum memory footprint you can tolerate
+# Note, hard-kills the ePPing process without allowing it to clean up. Consider
+# running /scripts/cleanup-tc-progs after.
+MemoryMax=4G
+
+[Install]
+WantedBy=default.target

pping/systemd-files/rotate-pping.service

@@ -0,0 +1,6 @@
+[Unit]
+Description=Rotates the output file from ePPing on %i (pping@%i.service)
+
+[Service]
+Type=oneshot
+ExecStart=/opt/bpf-examples/pping/scripts/rotate-pping-output.sh /var/log/pping/%i/pping.%i.json %i

pping/systemd-files/rotate-pping.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Rotate ePPing output for %i periodically
+PartOf=pping@%i.service
+
+[Timer]
+Unit=rotate-pping@%i.service
+
+# Rotate ePPing output every X seconds
+OnActiveSec=60
+OnUnitActiveSec=60
+AccuracySec=1us