Where to find logs/information about unattended-upgrades (apt)?

Question

Where can I find infos about when the unattend updates/upgrades run and what ist done (or IF something was done)?

I want to enable the unattended-upgrades (for security updates) on a debian virtual server and, yeah, on my RaspberryPi, too.

Do I have to search the /var/log/apt -logs for infos about WHAT was installed and /var/log/syslog about infos WHEN there was an action?

I see no CRON entry for when the update-process will run and the configs /etc/apt/apt.conf.d/20auto-upgrades and /etc/apt/apt.conf.d/50unattended-upgrades don't tell me either.

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Solution (credits to @bahamut):
sudo cat /var/log/unattended-upgrades/unattended-upgrades.log

2016-12-22 06:35:26,489 INFO Initial whitelisted packages: 
2016-12-22 06:35:26,489 INFO script for unattended-upgrades is executed
2016-12-22 06:35:26,489 INFO allowed sources are: ['origin=Debian,codename=jessie,label=Debian-Security']
2016-12-22 06:35:35,518 INFO Packages that will be upgraded: libsmbclient libtevent0 libwbclient0 python-samba samba samba-common samba-common-bin samba-dsdb-modules samba-libs samba-vfs-modules smbclient winbind
2016-12-22 06:35:35,523 INFO dpkg-protocol written to »/var/log/unattended-upgrades/unattended-upgrades-dpkg.log« 
2016-12-22 06:35:52,336 INFO all upgrades installed

Solution 1

Unattended upgrade has its own log-file in /var/log/unattended-upgrades/unattended-upgrades.log.

It is policed by anacron.

# These lines replace cron's entries
1   5   cron.daily  run-parts --report /etc/cron.daily
7   10  cron.weekly run-parts --report /etc/cron.weekly
@monthly    15  cron.monthly    run-parts --report /etc/cron.monthly

Additional information on what was done is located in /var/log/unattended-upgrades/unattended-upgrades-dpkg.log.

Solution 2

/var/log/dpkg.log also /var/log/apt/history.log

Both those log files contain timestamps and descriptions if action was taken. if no action was taken there is no log.

automated updates runs from /etc/cron.daily/apt and /etc/cron.daily/* runs from /etc/crontab in the early morning.

Comments

[Jasen]

it runs from /etc/cron.daily/apt

[jarno]

@Jasen or from /usr/lib/apt/apt.systemd.daily in systemd environment.