apt.py will not attempt to install i386 packages on an amd64 system

[Kingwad]

Bug report

On an amd64 systems with i386 architecture enabled, cloud-init will not install packages only available in i386

Steps to reproduce the problem

Enable i386 arch in early boot before apt update:

bootcmd:
- [ cloud-init-per, once, dpkgi386, dpkg, --add-architecture, i386]

Add package available to apt in i386

packages:
- steamcmd

cloud-init will not find the package to install. Package will install successfully from command line:

apt install steamcmd

Cause: cloud-init searches for packages using apt-cache pkgnames before attempting to install, which only lists packages for the primary architecture. Adding the --all-names flag to the call in apt.py does include packages for i386, but also includes virtual packages unavailable for installation.

Environment details

• Cloud-init version: 25.1.4
• Operating System Distribution: Debian 13 Trixie
• Cloud provider, platform or installer type: vultr

cloud-init logs

2026-09-07 17:24:37,859 - apt.py[DEBUG]: The following packages were not found by APT so APT will not attempt to install them: ['steamcmd']
2026-09-07 17:24:37,859 - distros[INFO]: Failed to install the following packages: ['steamcmd']. See associated package manager logs for more details.
2026-09-07 17:24:37,859 - log_util.py[WARNING]: Failure when attempting to install packages: ['steamcmd']
2026-09-07 17:24:37,860 - log_util.py[DEBUG]: Failure when attempting to install packages: ['steamcmd']
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py", line 95, in handle
cloud.distro.install_packages(pkglist)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
File "/usr/lib/python3/dist-packages/cloudinit/distros/init.py", line 286, in install_packages
raise PackageInstallerError(error_message % total_failed)
cloudinit.distros.PackageInstallerError: Failed to install the following packages: {'steamcmd'}. See associated package manager logs for more details.
2026-09-07 17:24:37,863 - cc_package_update_upgrade_install.py[WARNING]: 1 failed with exceptions, re-raising the last one
2026-09-07 17:24:37,863 - handlers.py[DEBUG]: finish: modules-final/config-package-update-upgrade-install: FAIL: running config-package-update-upgrade-install with frequency once-per-instance
2026-09-07 17:24:37,863 - log_util.py[WARNING]: Running module package-update-upgrade-install (<module 'cloudinit.config.cc_package_update_upgrade_install' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py'>) failed
2026-09-07 17:24:37,864 - log_util.py[DEBUG]: Running module package-update-upgrade-install (<module 'cloudinit.config.cc_package_update_upgrade_install' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py'>) failed
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/cloudinit/config/modules.py", line 297, in _run_modules
ran, _r = cc.run(
~~~~~~^
run_name, mod.handle, func_args, freq=freq
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/usr/lib/python3/dist-packages/cloudinit/cloud.py", line 71, in run
return self._runners.run(name, functor, args, freq, clear_on_fail)
~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 156, in run
results = functor(**args)
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py", line 127, in handle
raise errors[-1]
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py", line 95, in handle
cloud.distro.install_packages(pkglist)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
File "/usr/lib/python3/dist-packages/cloudinit/distros/init.py", line 286, in install_packages
raise PackageInstallerError(error_message % total_failed)
cloudinit.distros.PackageInstallerError: Failed to install the following packages: {'steamcmd'}. See associated package manager logs for more details.