Add monitor script to check for seed node connectivity and report issues

doc/monitor-bitsquare-sn.cron.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+# Report by email failing connections to Bitsquare seed nodes.
+#
+# Exit with status 2 if unreachable nodes were detected.
+#
+# You may drop this under ``/etc/cron.hourly``.
+# Please make sure that your system can send emails.
+#
+# Requirements: coreutils, torify, netcat, mail.
+#
+# Author: Ivan Vilata-i-Balaguer <ivan@selidor.net>
+
+
+## BEGIN CONFIGURATION
+# Email addresses to report failing nodes to, white-separated.
+REPORT_TO_EMAILS='
+bsqsn@example.com
+'
+
+# Seed node addresses to check as ONION_ADDRESS:PORT, white-separated.
+# Addresses from ``SeedNodesRepository`` v0.4.4.
+SEED_NODES='
+uadzuib66jupaept.onion:8000
+hbma455xxbqhcuqh.onion:8000
+wgthuiqn3aoiovbm.onion:8000
+2zxtnprnx5wqr7a3.onion:8000
+'
+## END CONFIGURATION
+
+
+failing_seed_nodes=''
+for sn in $SEED_NODES; do
+    true | torify nc $(echo "$sn" | tr ':' ' ') > /dev/null 2>&1
+    if [ $? != 0 ]; then
+        failing_seed_nodes="$failing_seed_nodes $sn"
+    fi
+done
+
+if [ "$failing_seed_nodes" ]; then
+    cat <<- EOF | mail -s "Failing Bitsquare seed nodes" -- $REPORT_TO_EMAILS
+	The following Bitsquare seed nodes failed to accept a new connection:
+
+	$(echo $failing_seed_nodes | tr ' ' '\n' | sed 's/^/    /')
+
+	Please check if they have issues, thank you.
+
+	-- 
+	The Bitsquare seed monitor running at $(hostname -f)
+	EOF
+	exit 2
+fi