Bug#910753: apt: Race condition between apt's systemd timers & cloud-init

[Ross Vandegrift <ross@kallisti.us>]

Package: apt
Version: 1.7.0
Severity: normal

Hello,

When a cloud VM is booted with systemd, the timers for apt's periodic actions
are launched in parallel with cloud-init.  cloud-init does some initial
setup, but it also allows end users to customize the system by e.g.,
installing packages with apt.

Depending on timing, apt-daily can go first and lock the db.  If the update
takes a while, then the db will still be locked when cloud-init tries to
apply the user's customizations.  Since this can happen on the first boot,
there's no clean way for an end-user to ensure that their packages will
install.  There's a useful ubuntu-focused discussion of this at [1].

Would you be open to adding cloud-init.target to the After list on
apt-daily.timer?  If I've understood the issue correctly, this should be
sufficient.  If units can use Before to delay timer triggers, this could be
done on the cloud-init side.  But I've been unable to confirm what systemd
does with that config.

Thanks,
Ross

[1] - https://unix.stackexchange.com/questions/315502/how-to-disable-apt-daily-service-on-ubuntu-cloud-vm-image


-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing'), (40, 'unstable'), (30, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.18.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages apt depends on:
ii  adduser                 3.118
ii  debian-archive-keyring  2017.7
ii  gpgv                    2.2.10-2
ii  libapt-pkg5.0           1.7.0
ii  libc6                   2.27-6
ii  libgcc1                 1:8.2.0-7
ii  libgnutls30             3.5.19-1
ii  libseccomp2             2.3.3-3
ii  libstdc++6              8.2.0-7

Versions of packages apt recommends:
ii  ca-certificates  20170717

Versions of packages apt suggests:
pn  apt-doc         <none>
ii  aptitude        0.8.11-3
ii  dpkg-dev        1.19.0.5
ii  gnupg           2.2.10-2
ii  gnupg2          2.2.10-2
ii  powermgmt-base  1.33
ii  synaptic        0.84.3

-- no debconf information