Automatic updates (#307)

docs/linux-service.md

@@ -57,3 +57,100 @@ Enable BGPalerter to start at boot and then start the service.
 `systemctl enable bgpalerter`
 
 `systemctl start bgpalerter`
+
+
+### Automatic Updates
+Enable automatic updates.
+
+`cd /home/bgpalerter`
+
+`vi upgrade.sh`
+
+The file needs to be executable
+```
+chmod +x upgrade.sh
+chown bgpalerter:bgpalerter /home/bgpalerter/upgrade.sh
+```
+
+The contents of this file should be as follows:
+
+```
+#!/usr/bin/env bash
+
+#If log file does not exist, create it
+if [ ! -f /home/bgpalerter/logs/upgrade.log ]; then
+  touch /home/bgpalerter/logs/upgrade.log
+  chown bgpalerter:bgpalerter /home/bgpalerter/logs/upgrade.log
+fi
+
+#Log everything if executing manually
+exec 1> /home/bgpalerter/logs/upgrade.log 2>&1
+set -vex
+PS4='+\t '
+
+#Download the latest version and save it to a temp file
+wget -O bgpalerter-linux-x64.tmp https://github.com/nttgin/BGPalerter/releases/latest/download/bgpalerter-linux-x64
+
+#Set permissions and ownership to execute the file and capture the version
+chmod +x bgpalerter-linux-x64.tmp
+chown -R bgpalerter:bgpalerter /home/bgpalerter/
+
+#Set variables to compare versions
+if [ -f bgpalerter-linux-x64 ]; then
+  #If a file exists already
+  v1=$(./bgpalerter-linux-x64 -v)
+  v2=$(./bgpalerter-linux-x64.tmp -v)
+
+else
+  #If the file does not exist - For testing purposes
+  v1=$"0"
+  v2=$(./bgpalerter-linux-x64.tmp -v)
+fi
+
+#If the versions are not the same
+if [ "$v1" == "0" ];then
+  #Rename the temp file
+  mv bgpalerter-linux-x64.tmp bgpalerter-linux-x64
+
+  #Restart the service
+  systemctl restart bgpalerter
+
+  #Pause for one second for service to fully start
+  sleep 1
+
+elif [ "$v1" != "$v2" ];then
+  #Rename the old binary and append the version
+  mv bgpalerter-linux-x64 "bgpalerter-linux-x64-$v1"
+
+  #Rename the temp file
+  mv bgpalerter-linux-x64.tmp bgpalerter-linux-x64
+
+  #Restart the service
+  systemctl restart bgpalerter
+  
+  #Pause for one second for service to fully start
+  sleep 1
+
+else
+  #If the versions are the same - delete the temp file
+  rm bgpalerter-linux-x64.tmp
+fi
+
+#Log service status
+systemctl status bgpalerter -l
+
+#Delete renamed binaries older than 60 days
+find -type f -name 'bgpalerter-linux-x64-*' -mtime +60 -delete
+
+#Delete log file if larger than 5MB
+find /home/bgpalerter/logs/ -type f -name "upgrade.log" -size +5M -delete
+```
+
+Configure a cron job to run, in this case, weekly.
+
+`crontab -e`
+
+The contents of this file should be as follows:
+```
+0 0 * * 0 /home/bgpalerter/bgpalerter/upgrade.sh
+```