[wildfly-dev] Reading Logs from Web Console

[James R. Perkins]

On 08/14/2013 11:45 AM, Brian Stansberry wrote:
> On 8/14/13 12:55 PM, James R. Perkins wrote:
>> That's my thinking too. The only complaint I've had about that solution
>> is that it can't be filtered since it's just raw text. I had a working
>> example operation that just took a file name and the number of bytes to
>> read. To me this is the best solution, but it wouldn't have access to
>> anything in a syslog or the console. Though that's okay IMO since they
>> likely have other viewers for those.
>>
>> I'll resurrect that example. It shouldn't take all that long. One thing
>> to note is it will only allow files to be read that are in the
>> jboss.server.log.dir (and possibly only files that end in *.log?).
>>
> That's only true if the viewer operation is not associated with a
> management resource that maps to the log file (i.e. the appender resource).
>
> I think it's a mistake to create any kind of viewer that can serve an
> arbitrary file.
>
> For cases of serving previous versions of the file (i.e. ones before the
> current with any kind of rolling appender) the API can expose a param
> that allows the desired file to be chosen but only from a set of files
> that the management resource knows it created.
The only reason I thought of limiting it to the jboss.server.log.dir was 
there is no real way to know what handlers are file handlers. For 
example a custom-handler could be a file handler, but there is no real 
way to know that. Those files should be allowed to viewed, IMO, as well.

On the other hand I do agree there is an issue with being able to read 
arbitrary files. A good example would be if the logs are placed in 
/var/log/ we don't want to allow access to any of the log files not 
created by WildFly.

I guess what we could do, at least to start, is just add a read-log 
operation only to file handlers. Then we could just get the file name 
from the resource. Further down maybe we could add an attribute to the 
custom-handler to enable the operation.
>
>> So in general I agree here, I think this is the best, the least invasive
>> approach and the lowest performance hit.
>>
>> On 08/14/2013 10:36 AM, Jason Greene wrote:
>>> IMO the best solution is a management operation that simply displays portions of the log file. The dependency on the log file is IMO not a problem because we support multiple appenders.
>>>
>>> On Aug 14, 2013, at 12:03 PM, James R. Perkins <jperkins at redhat.com> wrote:
>>>
>>>> I had posted this to another list, but this is a more appropriate place for it. I think there needs to be a general discussion around this as it's been mentioned, at least to me, a few times here and there and I know Heiko raised the issue some time a go now.
>>>>
>>>> The original JIRA, WFLY-280[1], is to display the last 10 error messages only. To be honest I wouldn't find that very useful. To me if I'm looking for logs I want to see all logs, but that's not always so easy. Like the syslog-handler which doesn't log to a file so there is no way to read those messages back.
>>>>
>>>> The current plan for the last 10 error messages is we store messages in a queue that can be accessed via an operation. This works fine until     the error message you're interested in is 11 or you want to see warning messages.
>>>>
>>>> Another option I had come up with is reading back the contents of the file, for example the server.log. This could be problematic too in that there is no way to filter information like only see error messages or only see warning messages. To solve this I have considered creating a JSON formatter so the results could be queried, but I don't think it should be a default which would mean it's not reliable for the console to assume it's getting back JSON.
>>>>
>>>> I've also thought about, haven't tested this and it may not work at all, creating a handler that uses websockets to send messages. I'm not sure how well this would work and it's possible it may not even work for bootstrap logging.
>>>>
>>>> With regards to audit logging, we're probably going to have to do something totally different from what we'll do in the logging subsystem since it doesn't use standard logging.
>>>>
>>>> I guess the bottom line is what does the console want to see? Do you want to see all raw text log messages? Do you want all messages but in a format like JSON that you can query/filter? Do you really want only the last 10 error messages only? All or none of these might be possible, but I really need to understand the needs before I can explore more in depth what the best option would be.
>>>>
>>>> [1]: https://issues.jboss.org/browse/WFLY-280
>>>> --
>>>> James R. Perkins
>>>> Red Hat JBoss Middleware
>>>>
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>>>> wildfly-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/wildfly-dev
>>> --
>>> Jason T. Greene
>>> WildFly Lead / JBoss EAP Platform Architect
>>> JBoss, a division of Red Hat
>>>
>

-- 
James R. Perkins
Red Hat JBoss Middleware