Checking libnm/NM version mismatch

[Till Maas <till redhat com>]

Hi,

one of the Nmstate ours accidentally used Nmstate on a machine after
updating NM without restarting it on CentOS 8. Therefore the system
used libnm 1.20 with NM 1.14. This resulted in an error like

Connection adding failed: error=nm-connection-error-quark:
bridge.vlans: unknown property (7)

How can we improve this error message?

My initial idea would be to compare the versions of NM and libnm in
Nmstate and warn/abort if there is a mismatch:
AFAICS we can check the NM version with NMClient.get_version() and the
libnm version seems to be available with

struct.unpack("xBBB", struct.pack(">I", NM.utils_version()))

(not so convenient that the version identifiers are in different
encodings, to be honest).

How about we add a warning/an error to Nmstate in case the versions
mismatch? Do you prefer a warning or an error? Do you have other
suggestions?

Kind regards
Till

--
Till Maas
He/His/Him
Ansible RHEL Networking System Role Maintainer

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