op-mode: T5514: Allow safe reboots to config defaults when config.boot is deleted (backport #3654)

[mergify]

Change Summary

• Added flag to vyos.config_mgmt.unsaved_commits() that will tolerate missing config.boot for specific circumstances
• Shutdown/reboot uses this flag; config will regenerate from defaults after a reboot

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5514

Related PR(s)

Component(s) name

• op-mode

Proposed changes

I considered regenerating config.boot from defaults on the spot; that will rarely work well. There may also be situations where unsaved_commits() is expected to fail.

This fix is for a specific situation:

• User has deleted /config/config.boot
• User wants to reboot back to a default config, cleanly
• User has not deleted anything else on the system - this is not a full factory reset or intended to be such
• User will be safely warned that there is unsaved configuration via the normal prompts
  • Breaking out at this point and issuing a save works fine
• Following a reboot, the default config.boot regenerates cleanly

How to test

vyos@TEST-VYOS-LEFT:~$ rm /config/config.boot
vyos@TEST-VYOS-LEFT:~$ reboot
Warning: there are unsaved configuration changes!
Run 'save' command if you do not want to lose those changes after reboot/shutdown.
Are you sure you want to reboot this system? [y/N] y

[...1 reboot & re-IP later...]

vyos@vyos:~$ 

Smoketest result

No smoketests exist for opmode, but tried to double check over config functions:

vyos@TEST-VYOS-LEFT:~$ python3 /usr/libexec/vyos/tests/smoke/cli/test_configd_inspect.py 
test_config_modification (__main__.TestConfigdInclude.test_config_modification) ... ok
test_file_instance (__main__.TestConfigdInclude.test_file_instance) ... ok
test_function_instance (__main__.TestConfigdInclude.test_function_instance) ... ok
test_signatures (__main__.TestConfigdInclude.test_signatures) ... ok

----------------------------------------------------------------------
Ran 4 tests in 0.569s

OK
vyos@TEST-VYOS-LEFT:~$ python3 /usr/libexec/vyos/tests/smoke/cli/test_configd_init.py 
test_configd_init (__main__.TestConfigdInit.test_configd_init) ... ok

----------------------------------------------------------------------
Ran 1 test in 0.123s

OK
vyos@TEST-VYOS-LEFT:~$ python3 /usr/libexec/vyos/tests/smoke/system/test_config_mount.py 
test_config_dir (__main__.TestConfigDir.test_config_dir) ... ok

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

---

This is an automatic backport of pull request #3654 done by [Mergify](https://mergify.com).

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