[Bug 1575572] Re: apache2 fails to start if installed via cloud config (on Xenial)

[Steve Langasek]

> The problem seems to be that any package install during systemd boot of
> a package that only provides sysvinit scripts will fail.  Reading invoke-rc.d,
> i'm not really sure why a proper systemd service woudlnt fail also.

The RUNLEVELHELPER check is buggy, yes.  However, the behavior of
invoke-rc.d is by design; if the runlevel can't be determined (which
according to systemd it still would not be, even if the bug in invoke-
rc.d was fixed), invoke-rc.d should default to doing nothing because
there's no system policy to say whether the service should be started.

I think there's a case to be made that this is a bug in systemd, for
returning 'unknown' for the runlevel in these cases.  The historical
behavior of sysvinit is that everything triggered from /etc/init.d/rc
inherits the value of the current runlevel in the RUNLEVEL environment
variable; and running e.g. 'RUNLEVEL=2 runlevel' - including on systemd
- will report this env value as the target runlevel.

$ runlevel
N 5
$ PREVLEVEL=5 RUNLEVEL=2 runlevel
5 2
$

Unless cloud-init is being called so early in boot that the runlevel
target is not known - which seems very unlikely - then I think the
correct thing for systemd to do is to honor this historical behavior by
making the 'runlevel' command return the target runlevel when called
from a systemd unit that's run at boot, even if that target has not yet
been reached.  Opening a task on systemd for this.

Note, BTW, that the above also suggests a workaround for cloud-init to
employ.  If for whatever reason systemd will not set itself up to return
the proper runlevel value, cloud-init can simply set RUNLEVEL=2 in the
environment prior to calling dpkg, and invoke-rc.d will pick this up and
DTRT with it.


** Also affects: systemd (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: systemd (Ubuntu)
   Importance: Undecided => High

** Changed in: systemd (Ubuntu)
       Status: New => Triaged

** Changed in: systemd (Ubuntu)
     Assignee: (unassigned) => Martin Pitt (pitti)

** Changed in: init-system-helpers (Ubuntu)
   Importance: High => Low

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1575572

Title:
  apache2 fails to start if installed via cloud config (on Xenial)

Status in cloud-init package in Ubuntu:
  Confirmed
Status in init-system-helpers package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Triaged

Bug description:
  Using the following cloud config, apache2 will fail to start on
  installation on Xenial:

  #cloud-config
  packages:
  - apache2

  See for example:

  $ gcloud compute instances create xenial-$(date +%y%m%d-%H%M) --image ubuntu-1604-xenial-v20160420c --image-project ubuntu-os-cloud --metadata-from-file user-data=cloud-config
  NAME                ZONE            MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP    STATUS
  xenial-160427-1050  europe-west1-d  n1-standard-1               10.240.0.7   104.155.86.94  RUNNING

  $ ssh ubuntu at 104.155.86.94 systemctl status apache2.service
  ● apache2.service - LSB: Apache2 web server
     Loaded: loaded (/etc/init.d/apache2; bad; vendor preset: enabled)
    Drop-In: /lib/systemd/system/apache2.service.d
             └─apache2-systemd.conf
     Active: inactive (dead)
       Docs: man:systemd-sysv-generator(8)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1575572/+subscriptions