interfaces: T6519: harden config migration if ethernet interface is missing

[c-po]

Change Summary

During a corner case where the configuration is migrated to a different system with fewer ethernet interfaces, migration will fail during an image upgrade.

vyos.ethtool.Ethtool() is instantiated with an invalid interface leading to an exception that kills the migrator

This fixes the following error:

vyos@vyos# load /usr/libexec/vyos/tests/config/bgp-evpn-l3vpn-pe-router
Loading configuration from '/usr/libexec/vyos/tests/config/bgp-evpn-l3vpn-pe-router'

Migration script error: /opt/vyatta/etc/config-migrate/migrate/interfaces/20-to-21: [Errno 1] failed to run command: ['/opt/vyatta/etc/con
fig-migrate/migrate/interfaces/20-to-21', '/tmp/tmprr8xf78f']
- op: set path: ['interfaces', 'ethernet', 'eth0', 'offload', 'gro'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth0', 'offload', 'gso'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth0', 'offload', 'sg'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth0', 'offload', 'tso'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth1', 'offload', 'gro'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth1', 'offload', 'gso'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth1', 'offload', 'sg'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth1', 'offload', 'tso'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth2', 'offload', 'gro'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth2', 'offload', 'gso'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth2', 'offload', 'sg'] value: None replace: True
- op: set path: ['interfaces', 'ethernet', 'eth2', 'offload', 'tso'] value: None replace: True

exit code: 1.

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/T6519

Related PR(s)

Component(s) name

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

[github-actions]

👍
No issues in PR Title / Commit Title

[c-po]

@Mergifyio backport sagitta circinus

[mergify]

backport sagitta circinus

✅ Backports have been created

• #3725 interfaces: T6519: harden config migration if ethernet interface is missing (backport #3724) has been created for branch sagitta
• #3726 interfaces: T6519: harden config migration if ethernet interface is missing (backport #3724) has been created for branch circinus