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Subject: Re: [ndctl PATCH 2/4] ndctl, monitor: set default log destination to
 syslog if "--daemon" is specified
References: <20180807131756.23673-1-qi.fuli@jp.fujitsu.com>
 <20180807131756.23673-3-qi.fuli@jp.fujitsu.com>
 <7aa147ac-9fa8-ace7-a782-6ba3cab88b20@gmail.com>
 <0DEDF3B159719A448A49EF0E7B11E3223DA9DD3A@g01jpexmbkw24>
From: Masayoshi Mizuma <msys.mizuma@gmail.com>
Message-ID: <01b090d0-64ee-8484-3183-313f1071421b@gmail.com>
Date: Wed, 8 Aug 2018 09:35:26 -0400
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To: qi.fuli@jp.fujitsu.com, linux-nvdimm@lists.01.org
List-ID: <linux-nvdimm@lists.01.org>

HiQi,

On 08/07/2018 09:31 PM, Qi, Fuli wrote:
...
>> 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.

Ummm... is this right behavior...? If the monitor running as a daemon,
shouldn't the default log destination be standard...? 
How about the following change?

diff --git a/ndctl/monitor.c b/ndctl/monitor.c
index f10384b..3778334 100644
--- a/ndctl/monitor.c
+++ b/ndctl/monitor.c
@@ -611,8 +611,11 @@ int cmd_monitor(int argc, const char **argv, void *ctx)
        if (argc)
                usage_with_options(u, options);
 
-       /* default to log_standard */
-       ndctl_set_log_fn((struct ndctl_ctx *)ctx, log_standard);
+       /* Set default log destination */
+       if (monitor.daemon)
+               ndctl_set_log_fn((struct ndctl_ctx *)ctx, log_syslog);
+       else
+               ndctl_set_log_fn((struct ndctl_ctx *)ctx, log_standard);
 
        if (monitor.verbose)
                ndctl_set_log_priority((struct ndctl_ctx *)ctx, LOG_DEBUG);

> 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).

I'm sorry, but I'm not clear about c)... The './standard' check should not have
the effect in case of c), right?
We should check the following three cases for monitor daemon, right?

1. '--log standard' option, or
2. In config file 'log = standard'
3. Both 1. and 2. is not set (default behavior).

If I miss something, sorry about that...

Thanks,
Masa

> 
> 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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