[libvirt] Is DBus a hard dependency

[Daniel P. Berrange]

On Sat, Nov 24, 2012 at 06:34:35PM +0100, Guido Günther wrote:
> Hi,
> currently running libvirtd without DBus fails due to:
> 
> error : nwfilterDriverStartup:208 : DBus matches could not be installed. Disabling nwfilter driver
> error : virDBusGetSystemBus:77 : internal error Unable to get DBus system bus connection: Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory
> error : virStateInitialize:810 : Initialization of NWFilter state driver failed
> error : daemonRunStateInit:784 : Driver state initialization failed
> 
> because we fail driver initialization hard in nwfilter_driver.c:
> 
>     if (nwfilterDriverInstallDBusMatches(sysbus) < 0) {
>         VIR_ERROR(_("DBus matches could not be installed. Disabling nwfilter "
>                   "driver"));
>         /*
>          * unfortunately this is fatal since virNWFilterTechDriversInit
>          * may have caused the ebiptables driver to use the firewall tool
>          * but now that the watches don't work, we just disable the nwfilter
>          * driver
>          */
>         goto error;
>     }
> 
> I wonder if this on prupose or if we can just make this a soft error and
> go on without DBus? At least in the !HAVE_FIREWALLD case it should be
> o.k. to continue. Shouldn't it? See attached patch.

Generally, if DBus has been requested at compile time, it ought to
be treated as compulsory, otherwise it should be non-fatal.


> >From 22571860568bfe8026e60dcede8f332ec6fd002f Mon Sep 17 00:00:00 2001
> Message-Id: <22571860568bfe8026e60dcede8f332ec6fd002f.1353774807.git.agx at sigxcpu.org>
> From: =?UTF-8?q?Guido=20G=C3=BCnther?= <agx at sigxcpu.org>
> Date: Sat, 24 Nov 2012 17:32:59 +0100
> Subject: [PATCH] nwfilter: Allow DBus initialization to fail
> To: libvir-list at redhat.com
> 
> in case we don't use firewalld. This allows us to run without
> DBus on servers.
> ---
>  src/nwfilter/nwfilter_driver.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c
> index 12f47ef..e4f6ec9 100644
> --- a/src/nwfilter/nwfilter_driver.c
> +++ b/src/nwfilter/nwfilter_driver.c
> @@ -204,6 +204,7 @@ nwfilterDriverStartup(int privileged)
>       * initializing
>       */
>      if (nwfilterDriverInstallDBusMatches(sysbus) < 0) {
> +#if HAVE_FIREWALLD
>          VIR_ERROR(_("DBus matches could not be installed. Disabling nwfilter "
>                    "driver"));
>          /*
> @@ -213,6 +214,7 @@ nwfilterDriverStartup(int privileged)
>           * driver
>           */
>          goto error;
> +#endif
>      }

IMHO any conditional should be in the nwfilterDriverInstallDBusMatches method
itself. ie that method should be a no-op hardcoded to return 0, if firewalld
has been disabled at compile time.

Daniel
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