[ovs-discuss] OVS Python IDL fetching database

[Numan Siddique]

On Thu, Jan 16, 2020 at 6:26 PM mkobus <mkobus at o2.pl> wrote:
>
> Hi MailingList!
>
> I'm trying to write Python script using OVS library to fetch DB content and print all current bridges, ports and interfaces. Following snippet shows what I deduced so far from examples found in https://mail.openvswitch.org/pipermail/ovs-dev/2018-July/349200.html:
>
> ```
> import ovs.db.idl
> import ovs.poller
>
> SCHEMA_PATH = "/usr/share/openvswitch/vswitch.ovsschema"
> SOCKET_PATH = 'punix:/run/openvswitch/db.sock'
>
> schema_helper = ovs.db.idl.SchemaHelper(SCHEMA_PATH)
>
> schema_helper.register_columns(
>     "Bridge", ["name", "ports"]
> )
> schema_helper.register_columns(
>     "Port", ["name", "interfaces"]
> )
> schema_helper.register_columns(
>     "Interface", []
> )
>
> idl = ovs.db.idl.Idl(SOCKET_PATH, schema_helper)
>
> while not idl.run():
>     poller = ovs.poller.Poller()
>     print('Seqno value {}'.format(idl.change_seqno))
>     idl.wait(poller)
>     poller.block()
> ```
>
> As I understand idl.run() should return `True` after DB content was fetched. In my case this loop is infinite - seqno doesn't change. There is no error though.
>
> I checked listing OVS resources using cli for version:

Seems to me you are doing something wrong.

You can refer this file
https://github.com/openvswitch/ovs/blob/master/tests/test-ovsdb.py#L648
 which tests the OVS python idl code.

There is this ovsdbapp python library which internally uses the ovs
python idl if you are interested to look into -
https://github.com/openstack/ovsdbapp

Thanks
Numan

>
> ovs-vsctl (Open vSwitch) 2.9.5
> DB Schema 7.15.1
>
> and those commands worked perfectly fine.
>
> Has anyone encountered similar issue?
>
> Regards,
> MK
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