Noninteractive frontend for apt-get

[cderici]

DEBIAN_FRONTEND=noninteractive is used for disabling all interactions
on apt-get install.

https://bugs.launchpad.net/juju/+bug/2011637 reports that their
upgrade was stuck in a grub prompt during an apt-get install. This
change precedes apt-get install command with the
DEBIAN_FRONTEND=noninteractive env variable to ensure no prompts or
interactions happen during apt-get.

According to the man 7 debconf, this env variable "makes the default
answers be used for all questions".

This also fixes some linter issues.

QA steps

For this package per se, run things like:

 $ make test
 $ make static-check

For testing the actual change:

 $ juju switch 3.4

Pull this change and point Juju's packaging package to your local path where you keep this change:

replace github.com/juju/packaging/v2 => <path-to->/packaging

Alternatively you can directly point to this change: (add the following to the go.mod in Juju):

replace github.com/juju/packaging/v2 => github.com/cderici/packaging/v2 noninteractive-frontend-JUJU-6135

After this, just build, bootstrap, deploy and play around to make sure nothing is broken (which means something's changed in the apt-get install and apt-get remove stuff).

 $ make build && make install
 $ juju bootstrap localhost
 $ juju deploy ubuntu
 $ juju remove-application ubuntu

[hpidcock]

To test this I needed to:

Downgrade distro-info

ubuntu@juju-1b3bf6-0:~$ apt list distro-info -a
Listing... Done
distro-info/jammy-updates,now 1.1ubuntu0.2 amd64 [installed,automatic]
distro-info/jammy 1.1build1 amd64
ubuntu@juju-1b3bf6-0:~$ sudo apt install distro-info=1.1build1
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Suggested packages:
  shunit2
The following packages will be DOWNGRADED:
  distro-info
0 upgraded, 0 newly installed, 1 downgraded, 0 to remove and 5 not upgraded.
Need to get 19.1 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] ...

Upgrade the controller

juju upgrade-controller --build-agent

But it said machine-0: 08:36:17 INFO juju.worker.upgradesteps upgrade steps for 3.4.4.3 have already been run. so that means I need to bump the juju version a bit more. So I changed version/version.go to 3.4.5.

So I upgraded the controller again (this time to 3.4.5...)

juju upgrade-controller --build-agent

Then I can see in debug-log it has upgraded the distro-info package

machine-0: 08:41:52 INFO juju.upgrade updating distro-info
machine-0: 08:41:52 INFO juju.packaging.manager Running: apt-get --option=Dpkg::Options::=--force-confold --option=Dpkg::Options::=--force-unsafe-io --assume-yes --quiet update
machine-0: 08:41:52 INFO juju.state.pool.txnwatcher txn watcher started
machine-0: 08:41:53 INFO juju.apiserver.connection agent login: machine-0 for 73120324-ad3d-48c3-82a0-f3ca2cee2931
machine-0: 08:41:53 INFO juju.apiserver.connection agent disconnected: machine-0 for 73120324-ad3d-48c3-82a0-f3ca2cee2931
machine-0: 08:41:54 INFO juju.packaging.manager Running: apt-get --option=Dpkg::Options::=--force-confold --option=Dpkg::Options::=--force-unsafe-io --assume-yes --quiet install distro-info
machine-0: 08:41:57 INFO juju.worker.upgradesteps signalling that this controller is ready for upgrade
machine-0: 08:41:57 INFO juju.worker.upgradesteps waiting for other controllers to be ready for upgrade
machine-0: 08:41:58 INFO juju.worker.upgradesteps finished waiting - all controllers are ready to run upgrade steps
machine-0: 08:41:58 INFO juju.worker.upgradesteps starting upgrade from 3.4.4.1 to 3.4.5.4 for "machine-0"
machine-0: 08:41:58 INFO juju.upgrade All upgrade steps completed successfully
machine-0: 08:41:58 INFO juju.worker.upgradesteps upgrade to 3.4.5.4 completed successfully.

[hpidcock]

Please ensure to add more tests to the juju/juju PR.