create new cli flags [RHOSRFE-61]

[dsneddon]

This spec would create several new CLI flags: current-config,
rollback, no-abort, and add functionality to detect ip duplicates
when using --noop.
--current-config
Be able to remove interfaces without using the
overly disruptive --cleanup option, and pass os-net the existing
configuration file as well as the new one so that a delta may be
calculated and applied accordingly.
--rollback
In the event of failure to apply the network, revert back to the
previous configuration.
--no-abort
Continue to try and apply the rest of the configuration, even if one
interface fails, and exit with a special return code in this case.
--noop
Change behavior so that when using --noop os-net-config would
attempt to detect if any of the IP addresses are already in use on
hosts other than the current host. This would allow a trial run to
predict whether any IP conflicts would occur during a production
run.

[karthiksundaravel]

Instead of a complete rollback, can we consider configuring the minimal networks needed to enable ssh and other bare minimum tasks ?

[karthiksundaravel]

This is the current design as well. The errors in applying the configurations does not break the flow usually.

[yiytan]

May I suggest a different design option for removing interfaces in nmstate?

1. let os-net-config save nmstate current config file in '/var/lib/os-net-config/nmstate_files/config.yaml' once configuration is successful
2. keep using --cleanup flag instead of introducing a new --current-config flag: Currently in ifcfg, --cleanup is used to remove unconfigured interfaces that was configured by os-net-config, if we use the same --cleanup flag, we achieve parity with ifcfg
3. remove cleanup_all_ifaces() function used by cleanup. I don't see when we will ever need to remove all interfaces including those not configured by os-net-config
4. introduce delete_ifaces() function for the cleanup. This function read the current config file from '/var/lib/os-net-config/nmstate_files/config.yaml', and compare with the interface objects from the new configuration file. If it's no longer in these new interface objects, it will be deleted

This design will have no change to CLI command thus user don't need to be involved in interface deletion. This design will let nmstate handling of removing interface using --cleanup flag, the same way as ifcfg.

[karthiksundaravel]

@yiytan

We have a recent patch [1] where the cleanup is done only for interfaces not defined in config.yaml with the exceptions that OVS interface, ovs bridges and SRIOV Pfs cannot be removed even when these are not defined in config.yaml

[1] os-net-config/os-net-config@805ec05

[yiytan]

@karthiksundaravel so what exactly it is to cleanup on nmstate cleanup? It will still cleanup interfaces that was not initially created by os-net-config right?

[yiytan]

@karthiksundaravel the issue is with using netinfo.show_running_config()[Interface.KEY], this gave all interfaces including the ones not configured by os-net-config (i.e. never was in the config.yaml)

[yiytan]

@karthiksundaravel

Based on your recent submission, we can add the support of deletion of existing interfaces that were in current config.yaml but not in new config.yaml. This will ensure we only delete interfaces that were configured by os-net-config

1. save nmstate current config into '/var/lib/os-net-config/nmstate_files/config.yaml' once configuration is successful
2. keep using --cleanup flag instead of introducing a new --current-config flag
3. change cleanup_all_ifaces() function used by cleanup:

• remove calling of netinfo.show_running_config()[Interface.KEY],
• replace with function self.get_current_ifaces() to read in the current configured interfaces from '/var/lib/os-net-config/nmstate_files/config.yaml'

[karthiksundaravel]

@yiytan The --cleanup flag is used to remove the configuration of network devices not mentioned in config.yaml. If we need to remove interfaces which are not defined in new-config.yaml but defined in the previous-config.yaml then we can do with the changes you have suggested but with a different config flag.

[yiytan]

@karthiksundaravel --cleanup flag is used to remove the interfaces that's not defined in os-net-config's config.yaml

However, in nmstate, we mistakenly deleted the interfaces that's not even configured by os-net-config, i.e. interfaces that was not in previous config.yaml got deleted.

I created this PR to restrict --cleanup to remove only interfaces that were configured by os-net-config. Please review it.

os-net-config/os-net-config#230