I wouldn't rush into using it everywhere. I tried it recently while digging into yet another weird issue, and – coincidentally or not – I could never reproduce the issue with debugging enabled. It could of course be just bad luck, but given how often debugging interferes with timing and race conditions, it's not at all impossible that it did affect the outcome. When there is a danger of changing the behavior, installation tests should stick to the commands which we suggest to users.

We could however try to use it after a problem occurs, but it will require a bit of extra scripting to catch exceptions and do the cleanup, since dpkg/apt-get aren't good at rolling back failed attempts.

I have never seem this cause any problems:

apt  install -o Debug::pkgProblemResolver=1 ...

The issue you reference was probably not regarding apt but the debugging mode of some other software. For apt enabling this more verbose mode is perfectly safe to enable in buildbot. It can just as easily be reverted in buildbot if it would cause some issues.

If you are afraid of enabling it everywhere, could you at least start by adding it to the line

sudo sh -c 'DEBIAN_FRONTEND=noninteractive MYSQLD_STARTUP_TIMEOUT=180 apt-get -o Dpkg::Options::=--force-confnew install --allow-unauthenticated -y mariadb-server mariadb-client mariadb-common mariadb-test mysql-common libmysqlclient18'

so we get

sudo sh -c 'DEBIAN_FRONTEND=noninteractive MYSQLD_STARTUP_TIMEOUT=180 apt-get -o Debug::pkgProblemResolver=1 -o Dpkg::Options::=--force-confnew install --allow-unauthenticated -y mariadb-server mariadb-client mariadb-common mariadb-test mysql-common libmysqlclient18'

and I could debug e.g. http://buildbot.askmonty.org/buildbot/builders/kvm-deb-bionic-amd64/builds/8339/steps/minor-upgrade-deps/logs/stdio ?

Thanks

I didn't say it caused a problem. I said that it appeared to make a problem go away, which is more dangerous for testing than causing a problem, as it can lead to undetectable false negatives.
I'm not sure what other software it may be, as I only added debugging options to an apt call. It could however be an effect of another debugging option of the same kind, I added two or three of them in those attempts. I didn't investigate it in detail, because testing debugging capabilities of apt/dpkg wasn't my goal.

dbart Can we please start using this? If not everywhere, then at least as suggested above?

otto I've added `-o Debug::pkgProblemResolver=1` to the script that runs the minor-upgrade-deps tests, so you will now see the additional debugging output for that test

Here's the log of a rebuild of the build referenced in a previous comment with the new option in use: http://buildbot.askmonty.org/buildbot/builders/kvm-deb-bionic-amd64/builds/8408/steps/minor-upgrade-deps/logs/stdio

The verbose output was applied on at least one apt upgrade stage and that is enough for now, so closing issue.