RE: [ndctl PATCH 2/4] ndctl, monitor: set default log destination to syslog if "--daemon" is specified

["Qi, Fuli" <qi.fuli@jp.fujitsu.com>]

> -----Original Message-----
> From: Masayoshi Mizuma [mailto:msys.mizuma@gmail.com]
> Sent: Wednesday, August 8, 2018 4:30 AM
> To: Qi, Fuli/斉 福利 <qi.fuli@jp.fujitsu.com>; linux-nvdimm@lists.01.org
> Subject: Re: [ndctl PATCH 2/4] ndctl, monitor: set default log destination to syslog
> if "--daemon" is specified
> 
> Hi Qi,
> 
> On 08/07/2018 09:17 AM, QI Fuli wrote:
> > When running monitor as a daemon, if the log destination is "standard"
> > or a relative path for log file, the messages will not be able to be logged.
> > Sometimes, users may not notice that the default log destination is "standard"
> > when they start monitor daemon by systemctl, so they will lose messages.
> > This patch is used to fix the unfriendly interface. When running
> > monitor as a daemon, the default log destination will be changed to
> > syslog. Also, the messages will be forwarded to syslog if the log destination is
> a relative path for log file.
> >
> > Signed-off-by: QI Fuli <qi.fuli@jp.fujitsu.com>
> > ---
> >  Documentation/ndctl/ndctl-monitor.txt | 16 +++++++++++++++-
> >  ndctl/monitor.c                       |  5 ++++-
> >  ndctl/monitor.conf                    |  2 ++
> >  3 files changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/ndctl/ndctl-monitor.txt
> > b/Documentation/ndctl/ndctl-monitor.txt
> > index 1cba9ea..9a8d76b 100644
> > --- a/Documentation/ndctl/ndctl-monitor.txt
> > +++ b/Documentation/ndctl/ndctl-monitor.txt
> > @@ -67,7 +67,21 @@ OPTIONS
> >
> >  -l <file | syslog | standard>::
> >  --log=<file | syslog | standard>::
> > -	Output notifications to <file>, syslog or standard output.
> > +	Send log messages to the specified destination.
> > ++
> > +--
> > +<file>::
> > +	Send log messages to specified <file>. When fopen() is not able
> > +	to open <file>, log messages will be forwarded to syslog.
> > +syslog::
> > +	Send messages to syslog.
> > +standard::
> > +	Send messages to standard output.
> > +--
> > ++
> > +The default log destination is 'syslog' if "--daemon" is specified,
> > +otherwise 'standard'. Note that standard and relative path for <file>
> > +will not work if "--daemon" is specified.
> >
> >  -c::
> >  --config-file=::
> > diff --git a/ndctl/monitor.c b/ndctl/monitor.c index bf1f1d3..2f3d751
> > 100644
> > --- a/ndctl/monitor.c
> > +++ b/ndctl/monitor.c
> > @@ -93,7 +93,8 @@ static void log_file(struct ndctl_ctx *ctx, int priority, const
> char *file,
> >  	f = fopen(monitor.log, "a+");
> >  	if (!f) {
> >  		ndctl_set_log_fn(ctx, log_syslog);
> > -		err(ctx, "open logfile %s failed\n", monitor.log);
> > +		err(ctx, "open logfile %s failed, forward messages to syslog\n",
> > +				monitor.log);
> >  		did_fail = 1;
> >  		notice(ctx, "%s\n", buf);
> >  		goto end;
> > @@ -644,6 +645,8 @@ int cmd_monitor(int argc, const char **argv, void *ctx)
> >  	}
> >
> >  	if (monitor.daemon) {
> 
> Why don't you add './standard' check? Like as:
> 
>                 if (strncmp(monitor.log, "./standard", 10) == 0)
>                         error("daemon doesn't work for 'standard' log option");
>                         goto out;
> 
Hi Masa,

Thank you for your comment.

When running monitor as a daemon, the messages will not be able to be logged in following cases.
a) Users set the log destination to standard by using [--log] option or setting value of "log" in config file.
b) The log destination is standard by default.
c) Users set the log destination to a relative path of log file by using [--log] option or setting value of "log" in config file.

The './standard' check will only works for case a).

Also, it would be more friendly to set a default log destination to monitor daemon.

Thanks,
QI

> Thanks,
> Masa
> 
> > +		if (!monitor.log || strncmp(monitor.log, "./", 2) == 0)
> > +			ndctl_set_log_fn((struct ndctl_ctx *)ctx, log_syslog);
> 
> >  		if (daemon(0, 0) != 0) {
> >  			err((struct ndctl_ctx *)ctx, "daemon start failed\n");
> >  			goto out;
> > diff --git a/ndctl/monitor.conf b/ndctl/monitor.conf index
> > 857aadf..934e2c0 100644
> > --- a/ndctl/monitor.conf
> > +++ b/ndctl/monitor.conf
> > @@ -38,4 +38,6 @@
> >  # to standard output (log=standard) or to write into a special file
> > (log=<file>)  # by setting key "log". If this value is in conflict
> > with the value of  # [--log=<value>] option, this value will be ignored.
> > +# Note: Setting value to "standard" or relative path for <file> will
> > +not work # when running moniotr as a daemon.
> >  # log = /var/log/ndctl/monitor.log
> >
> 

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