[Gluster-devel] Dynamically changing firewalld services

[Kaushal M]

On Mon, Aug 31, 2015 at 5:15 PM, Kaushal M <kshlmster at gmail.com> wrote:
> Hi all,
>
> I wanted know if there is any existing information on how to manage
> dynamically changing services using firewalld. If there are none
> existing, could you please let us know if the approach we're following
> below is correct.
>
> We want to provide firewalld service configuration for GlusterFS. One
> of the properties of GlusterFS is that it has a set of fixed ports,
> and a set of dynamic ports, which need to be opened.
>
> We propose to ship 2 firewalld services with GlusterFS.
> - glusterfs-static - This contains the list of static ports that
> should be opened up. This is placed in /usr/lib/firewalld/services
> - glusterfs-dynamic - This will contain the list of dynamic ports.
> This will be shipped empty, and be placed in /etc/firewalld/services .
> The ports in this service will be kept updated by a couple of scripts,
> which hook into the glusterfs start/stop events.
>
> The scripts, add or remove ports from the glusterfs-dyanmic.xml file,
> and call `firewall-cmd --reload` to have firewalld reload
> configuration. We do it this way, instead of using a dbus call because
> we want the configuration to be persisted, and also applied live.
>
> We've tested this, and this works. But we'd like to validate this
> solution with you guys.
>
> Do you see any issues with our approach? Is there anything we could do
> to improve the solution.
>
> For reference, the glusterfs bug and proposed solution are available
> at [1] and [2].
>
> Thanks.
>
> Kaushal
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=1253967
> [2] http://review.gluster.org/11989
>
> PS: Apologies if I should have posted this to the users list instead.

I've had a private conversation with Christopher Blum (CCd), who
identified a major flaw with our current solution. Having firewalld
reload will cause any runtime rules that were set to be lost. This
should be avoided at all costs.

Chris suggested using firewalld dbus commands [1] which could solve
this. We have dbus commands to add/remove ports from a service
permanently. This is an alternative to updating the service xml files.
But we don't see a method to update a service during runtime.

There are dbus commands to add/remove ports to zones during runtime.
But this is not useful as we wouldn't know which zone to apply it to.
One of the reasons we chose to use services was this.

So now we have two questions,
1. Is there a way to do a runtime modification of a firewalld service
2. If not, is there a easy way to get active zones, which have our
services enabled and add/remove ports from them.

Thanks.

Kaushal

[1] https://www.mankier.com/5/firewalld.dbus
[2] https://www.mankier.com/5/firewalld.dbus#Interfaces-Org.fedoraproject.firewalld1.config.service