[libvirt] [PATCH 2/2] daemon: Limit default log level to journald to VIR_LOG_INFO

[Daniel P. Berrange]

On Tue, Aug 12, 2014 at 04:34:37PM +0200, Peter Krempa wrote:
> Libvirt is really chatty when the DEBUG log level is enabled. When a
> host uses journald we'd enable debug logging to journald when only
> specifying the debug log level. As journald may employ rate throttling
> this would lock up the daemon until it's able to flush all debug
> messages.
> 
> This patch changes the default log level to VIR_LOG_INFO when using the
> default (unconfigured) log output to journald.
> 
> To still allow debug logging to journad the user now has to explicitly
> specify journald as a log output with priority 1 in the "log_outputs"
> configuration option. This patch also changes the config file template
> to be explicit about this change and notify the user about the possible
> consequence of debug logging into journald.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1121955
> ---
>  daemon/libvirtd.c    | 10 +++++++++-
>  daemon/libvirtd.conf |  4 ++++
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c
> index 946081a..2783c97 100644
> --- a/daemon/libvirtd.c
> +++ b/daemon/libvirtd.c
> @@ -678,7 +678,15 @@ daemonSetupLogging(struct daemonConfig *config,
>          (godaemon || !isatty(STDIN_FILENO))) {
>          char *tmp;
>          if (access("/run/systemd/journal/socket", W_OK) >= 0) {
> -            if (virAsprintf(&tmp, "%d:journald", virLogGetDefaultPriority()) < 0)
> +            virLogPriority priority = virLogGetDefaultPriority();
> +
> +            /* By default we don't want to log too much stuff into journald as
> +             * it may employ rate limiting and thus blocking libvirt execution.
> +             */
> +            if (priority == VIR_LOG_DEBUG)
> +                priority = VIR_LOG_INFO;
> +
> +            if (virAsprintf(&tmp, "%d:journald", priority) < 0)
>                  goto error;
>              virLogParseOutputs(tmp);
>              VIR_FREE(tmp);

ACK, matches what I suggested we do previously.

Regards,
Daniel
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