一台操作系统为 Debian 8 的 Xen 服务器上的虚拟机每个月都会自动关闭，该虚拟机上安装了 docker 并且正在运行一些应用程序，我应该检查 Debian 8 上的哪些日志来找出问题？
我的虚拟机最后一次关闭是在 12 月 27 日早上 8 点，/var/log/syslog 的内容：
Dec 26 19:39:04 debian rsyslogd: [origin software="rsyslogd" swVersion="8.4.2" x-pid="917" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
Dec 26 19:39:04 debian systemd[1]: Reloading LSB: start Samba SMB/CIFS daemon (smbd).
Dec 26 19:39:04 debian smbd[2361]: Reloading /etc/samba/smb.conf: smbd.
Dec 26 19:39:04 debian systemd[1]: Reloaded LSB: start Samba SMB/CIFS daemon (smbd).
Dec 26 19:39:04 debian systemd[1]: Stopping LSB: Start zabbix-agent daemon...
Dec 26 19:39:04 debian zabbix-agent[2395]: zabbix_agentd stopping...done.
Dec 26 19:39:04 debian systemd[1]: Starting LSB: Start zabbix-agent daemon...
Dec 26 19:39:05 debian zabbix-agent[2401]: zabbix_agentd starting...done.
Dec 26 19:39:05 debian systemd[1]: Started LSB: Start zabbix-agent daemon.
Dec 26 19:39:12 debian anacron[601]: Job `cron.daily' terminated
Dec 26 19:39:12 debian anacron[601]: Normal exit (1 job run)
Dec 26 19:46:19 debian systemd[1]: Starting Cleanup of Temporary Directories...
Dec 26 19:46:19 debian rsyslogd0: action 'action 17' resumed (module 'builtin:ompipe') [try http://www.rsyslog.com/e/0 ]
Dec 26 19:46:19 debian rsyslogd-2359: action 'action 17' resumed (module 'builtin:ompipe') [try http://www.rsyslog.com/e/2359 ]
Dec 26 19:46:19 debian systemd[1]: Started Cleanup of Temporary Directories.
Dec 26 20:17:01 debian CRON[3555]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 26 21:17:01 debian CRON[5285]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 26 22:17:01 debian CRON[6985]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 26 23:17:01 debian CRON[8714]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 00:17:01 debian CRON[10446]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 01:17:01 debian CRON[12145]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 02:17:01 debian CRON[13962]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 03:17:01 debian CRON[15725]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 04:17:01 debian CRON[17438]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 05:17:01 debian CRON[19132]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 06:17:01 debian CRON[20867]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 06:25:01 debian CRON[21095]: (root) CMD (test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ))
Dec 27 07:17:01 debian CRON[22576]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 07:30:01 debian CRON[22955]: (root) CMD (test -x /etc/init.d/anacron && /usr/sbin/invoke-rc.d anacron start >/dev/null)
Dec 27 07:30:01 debian systemd[1]: Starting Run anacron jobs...
Dec 27 07:30:02 debian systemd[1]: Started Run anacron jobs.
Dec 27 07:30:02 debian anacron[22975]: Anacron 2.3 started on 2021-12-27
Dec 27 07:30:02 debian anacron[22975]: Will run job `cron.daily' in 5 min.
Dec 27 07:30:02 debian anacron[22975]: Jobs will be executed sequentially
Dec 27 07:35:02 debian anacron[22975]: Job `cron.daily' started
Dec 27 07:35:02 debian anacron[23128]: Updated timestamp for job `cron.daily' to 2021-12-27
Dec 27 07:43:39 debian rsyslogd: [origin software="rsyslogd" swVersion="8.4.2" x-pid="917" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
Dec 27 07:43:39 debian systemd[1]: Stopping LSB: Start zabbix-agent daemon...
Dec 27 07:43:39 debian zabbix-agent[23559]: zabbix_agentd stopping...done.
Dec 27 07:43:39 debian systemd[1]: Starting LSB: Start zabbix-agent daemon...
Dec 27 07:43:39 debian zabbix-agent[23565]: zabbix_agentd starting...done.
Dec 27 07:43:39 debian systemd[1]: Started LSB: Start zabbix-agent daemon.
Dec 27 07:43:39 debian anacron[22975]: Job `cron.daily' terminated
Dec 27 07:43:39 debian anacron[22975]: Normal exit (1 job run)
Dec 27 08:17:01 debian CRON[24555]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 09:17:01 debian CRON[26247]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 10:17:01 debian CRON[27958]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 11:17:01 debian CRON[29671]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 12:17:01 debian CRON[31394]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 13:17:01 debian CRON[33081]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 14:17:01 debian CRON[34795]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 15:17:01 debian CRON[36520]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 16:17:01 debian CRON[38232]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 17:17:01 debian CRON[39929]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 18:17:01 debian CRON[41647]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 19:17:01 debian CRON[43355]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 19:46:39 debian systemd[1]: Starting Cleanup of Temporary Directories...
Dec 27 19:46:39 debian systemd[1]: Started Cleanup of Temporary Directories.
Dec 27 20:17:01 debian CRON[45087]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 21:17:01 debian CRON[46841]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 22:17:01 debian CRON[48546]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 27 23:17:01 debian CRON[50266]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 00:17:01 debian CRON[51954]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 01:17:01 debian CRON[53665]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 02:17:01 debian CRON[55378]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 03:17:01 debian CRON[57099]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 04:17:01 debian CRON[58798]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 05:17:01 debian CRON[60506]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 06:17:01 debian CRON[62237]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 06:25:01 debian CRON[62465]: (root) CMD (test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ))
Dec 28 07:17:01 debian CRON[63965]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 28 07:30:01 debian CRON[64315]: (root) CMD (test -x /etc/init.d/anacron && /usr/sbin/invoke-rc.d anacron start >/dev/null)
Dec 28 07:30:01 debian systemd[1]: Starting Run anacron jobs...
Dec 28 07:30:01 debian systemd[1]: Started Run anacron jobs.
Dec 28 07:30:01 debian anacron[64335]: Anacron 2.3 started on 2021-12-28