cyclic dependencies, cloud-init.target has After=mutli-user.target

[ubuntu-server-builder]

This bug was originally filed in Launchpad as LP: #2003877

Launchpad details

affected_projects = []
assignee = None
assignee_name = None
date_closed = 2023-01-27T14:58:00.411468+00:00
date_created = 2023-01-25T15:29:45.975925+00:00
date_fix_committed = None
date_fix_released = None
id = 2003877
importance = undecided
is_complete = True
lp_url = https://bugs.launchpad.net/cloud-init/+bug/2003877
milestone = None
owner = izzette
owner_name = Isabelle COWAN-BERGMAN
private = False
status = invalid
submitter = izzette
submitter_name = Isabelle COWAN-BERGMAN
tags = []
duplicates = []

Launchpad user Isabelle COWAN-BERGMAN(izzette) wrote on 2023-01-25T15:29:45.975925+00:00

cloud-init.target is ordered after mutli-user.target as it contains the After=mutli-user.target directive. Advice is given in

cloud-init/systemd/cloud-init.target

Lines 7 to 9 in 7d57fcf

	# system configuration tasks have completed. To order a service after cloud-init
	# is done, add the directives as applicable:
	# After=cloud-init.target and Wants=cloud-init.target

:

system configuration tasks have completed. To order a service after cloud-init

is done, add the directives as applicable:

After=cloud-init.target and Wants=cloud-init.target

Following this advice will result in cyclic dependencies in systemd resolution if these directives are added to a unit which is WantedBy=multi-user.target. This is because the unit depending on and scheduled after cloud-init.target is WantedBy mutli-user.target as well which is itself ordered Before cloud-init.target. As adding new units to mutli-user.target is standard practice, this is likely to occur frequently. Related issues have been mentioned before in cloud-init bugs, for example: https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1629797/comments/11; as well as other bug trackers: https://bugzilla.redhat.com/show_bug.cgi?id=1393094.

This could be resolved by either of the two:

• removing the advice that results in cyclic dependencies
• cloud-init.target depends on basic.target

Additional information

Cloud provider: any

[ubuntu-server-builder]

Launchpad user Isabelle COWAN-BERGMAN(izzette) wrote on 2023-01-25T15:29:45.975925+00:00

Launchpad attachments: ubuntu-bug cloud-init

[ubuntu-server-builder]

Launchpad user James Falcon(falcojr) wrote on 2023-01-27T14:57:55.729923+00:00

That's why the statement contains the phrase "as applicable". If you have a unit that is "WantedBy=multi-user.target" then by definition, you don't want it running after cloud-init.target, so this advice isn't applicable to your use case. The advice is provided to inform a user how to order something after cloud-init has run, not how avoid all cyclic dependencies. Based on this, I'm going to set this to "Invalid", but if there's a deeper issue here that I'm not understanding, please do comment and set the status back to "New".