Re: [slf4j-user] Question: supporting ALL, OFF level

[Dongjin Lee]

Hi All,

Thanks for your great feedback. Before discussing this issue further, here
are some context.

As you already know, the log4j vulnerability crisis was a significant issue
recently. Of course, using slf4j as a facade and making log implementation
pluggable is THE SOLUTION but, it has one limitation: as Gülcü already
stated, slf4j does not support dynamic log level change feature, which is
such a desirable feature for maintenance.

Because of that, many projects can't use slf4j. For example, Apache Kafka
calls log4j API directly, and Spring boot uses logback, without the slf4j
facade.

(related discussion:
https://lists.apache.org/thread/4gyyjmfp92xvl1661qdgpx70l0gg04yd
disclaimer: I am working on Apache Kafka's log4j 2.x upgrading issue.)

Upon the context above, I hope to propose the following features to
slf4j-api:

1. Add OFF level, which enables dynamic turning on/off the logger.
2. Upon 1 and SLF4J-124, add Logger#setLevel(Level) method.

With this feature, for example, `slf4j-simple` can dynamically adjust its
logger level (`SimpleLogger#currentLogLevel`):

https://github.com/qos-ch/slf4j/blob/master/slf4j-simple/src/main/java/org/slf4j/simple/SimpleLogger.java

How do you think?

Best,
Dongjin

On Fri, Jan 28, 2022 at 4:40 AM Matt Sicker  wrote:

> It might be beneficial to support the equivalent of levels by
> interpreting them as integral values. log4j-api supports custom log
> levels, and those all work due to levels having an integral value to
> compare them against each other. From a Logger API perspective, it
> doesn't really make sense to log messages at OFF or ALL, especially as
> they tend to do the opposite of their name (e.g., logging at the OFF
> level means "always log" as OFF is a higher level than FATAL, while
> logging at the ALL level means it never gets logged as ALL is lower
> than TRACE).
>
> On Thu, Jan 27, 2022 at 9:57 AM Joakim Erdfelt 
> wrote:
> >
> > While slf4j is just a facade, there's a growing group of features in
> various projects that put configuration at the slf4j api level (both at
> startup and runtime), not at the slf4j implementation level.
> >
> > Am I wrong in assuming that the stated scope of this was for this
> proposal to have slf4j api level ability?
> >
> > - Joakim
> >
> > On Thu, Jan 27, 2022 at 8:42 AM Ceki Gülcü  wrote:
> >>
> >>
> >>
> >> On 1/27/2022 2:55 PM, Joakim Erdfelt wrote:
> >> > I like it.
> >> >
> >> > OFF is definitely useful, and should be there.
> >> >
> >> > ALL on the other hand seems redundant.
> >> > Just setting the most noisy level (TRACE in slf4j terms) would be the
> >> > equivalent end result.
> >>
> >> Unless I am forgetting something or getting forgetful, SLF4J does not
> >> allow users to set levels.
> >>
> >> > - Joakim
> >>
> >> --
> >> Ceki Gülcü
> >>
> >> Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch
> >> ___
> >> slf4j-user mailing list
> >> slf4j-user@qos.ch
> >> http://mailman.qos.ch/mailman/listinfo/slf4j-user
> >
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--
Dongjin Lee

A hitchhiker in the mathematical world.

github: github.com/dongjinleekr
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Re: [slf4j-user] Question: supporting ALL, OFF level

[Matt Sicker]

It might be beneficial to support the equivalent of levels by
interpreting them as integral values. log4j-api supports custom log
levels, and those all work due to levels having an integral value to
compare them against each other. From a Logger API perspective, it
doesn't really make sense to log messages at OFF or ALL, especially as
they tend to do the opposite of their name (e.g., logging at the OFF
level means "always log" as OFF is a higher level than FATAL, while
logging at the ALL level means it never gets logged as ALL is lower
than TRACE).

On Thu, Jan 27, 2022 at 9:57 AM Joakim Erdfelt  wrote:
>
> While slf4j is just a facade, there's a growing group of features in various 
> projects that put configuration at the slf4j api level (both at startup and 
> runtime), not at the slf4j implementation level.
>
> Am I wrong in assuming that the stated scope of this was for this proposal to 
> have slf4j api level ability?
>
> - Joakim
>
> On Thu, Jan 27, 2022 at 8:42 AM Ceki Gülcü  wrote:
>>
>>
>>
>> On 1/27/2022 2:55 PM, Joakim Erdfelt wrote:
>> > I like it.
>> >
>> > OFF is definitely useful, and should be there.
>> >
>> > ALL on the other hand seems redundant.
>> > Just setting the most noisy level (TRACE in slf4j terms) would be the
>> > equivalent end result.
>>
>> Unless I am forgetting something or getting forgetful, SLF4J does not
>> allow users to set levels.
>>
>> > - Joakim
>>
>> --
>> Ceki Gülcü
>>
>> Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch
>> ___
>> slf4j-user mailing list
>> slf4j-user@qos.ch
>> http://mailman.qos.ch/mailman/listinfo/slf4j-user
>
> ___
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Re: [slf4j-user] Question: supporting ALL, OFF level

[Joakim Erdfelt]

While slf4j is just a facade, there's a growing group of features in
various projects that put configuration at the slf4j api level (both at
startup and runtime), not at the slf4j implementation level.

Am I wrong in assuming that the stated scope of this was for this proposal
to have slf4j api level ability?

- Joakim

On Thu, Jan 27, 2022 at 8:42 AM Ceki Gülcü  wrote:

>
>
> On 1/27/2022 2:55 PM, Joakim Erdfelt wrote:
> > I like it.
> >
> > OFF is definitely useful, and should be there.
> >
> > ALL on the other hand seems redundant.
> > Just setting the most noisy level (TRACE in slf4j terms) would be the
> > equivalent end result.
>
> Unless I am forgetting something or getting forgetful, SLF4J does not
> allow users to set levels.
>
> > - Joakim
>
> --
> Ceki Gülcü
>
> Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch
> ___
> slf4j-user mailing list
> slf4j-user@qos.ch
> http://mailman.qos.ch/mailman/listinfo/slf4j-user
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Re: [slf4j-user] Question: supporting ALL, OFF level

[Ceki Gülcü]

On 1/27/2022 2:55 PM, Joakim Erdfelt wrote:
> I like it.
> 
> OFF is definitely useful, and should be there.
> 
> ALL on the other hand seems redundant.
> Just setting the most noisy level (TRACE in slf4j terms) would be the
> equivalent end result.

Unless I am forgetting something or getting forgetful, SLF4J does not
allow users to set levels.

> - Joakim

-- 
Ceki Gülcü

Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch
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Re: [slf4j-user] Question: supporting ALL, OFF level

[Ceki Gülcü]

Hello Dongjin,

Thank you very much for your very well researched message.

While the SLF4J API allows for logging at levels TRACE, DEBUG, INFO,
WARN and ERROR, the API does *not* allow the user to set the level of a
logger.

I would say that given that it makes no sense to log at levels OFF or
ON, it follows that there is no need to introduce these levels in SLF4J.

I would like to take you up for your offer for help, Do you have other
ideas for contribution?

Best

-- 
Ceki Gülcü

Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch



On 1/27/2022 2:36 PM, Dongjin Lee wrote:
> Hi, slf4j community,
> 
> I have a question on slf4j-api's Level definition.
> 
> As far as I know, the slf4j community is planning to support the dynamic
> logging level change feature with https://jira.qos.ch/browse/SLF4J-124
> . However, since slf4j-api only
> defines five levels, omitting `ALL` and `OFF` (below), we can't call a
> method like `logger.setLevel(Level.OFF)` - which is available in other
> logging frameworks.
> 
> https://github.com/qos-ch/slf4j/blob/master/slf4j-api/src/main/java/org/slf4j/event/EventConstants.java
> 
> 
> For example, logback supports seven levels (i.e., five common ones +
> ALL, OFF):
> 
> https://github.com/qos-ch/logback/blob/master/logback-classic/src/main/java/ch/qos/logback/classic/Level.java
> 
> 
> Log4j supports 8 levels (i.e., five common ones + FATAL, ALL, OFF):
> 
> https://logging.apache.org/log4j/2.x/log4j-api/apidocs/org/apache/logging/log4j/Level.html
> 
> 
> Java's official logging level definition is a little bit different, but
> they also support ALL, OFF:
> 
> https://docs.oracle.com/javase/7/docs/api/java/util/logging/Level.html
> 
> 
> So, in my humble opinion, to make the dynamic logging level change
> feature more complete, slf4j-api is much better to support ALL and OFF
> levels. What do you think?
> 
> If you agree and open an issue, I am willing to contribute.
> 
> Best,
> Dongjin
> 
> --
> 
> Dongjin Lee
> 
> A hitchhiker in the mathematical world.
> 
> github: github.com/dongjinleekr 
> keybase: https://keybase.io/dongjinleekr 
> linkedin: kr.linkedin.com/in/dongjinleekr
> 
> speakerdeck: speakerdeck.com/dongjin 
> //
> 
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Re: [slf4j-user] Question: supporting ALL, OFF level

[Joakim Erdfelt]

I like it.

OFF is definitely useful, and should be there.

ALL on the other hand seems redundant.
Just setting the most noisy level (TRACE in slf4j terms) would be the
equivalent end result.

- Joakim

On Thu, Jan 27, 2022 at 7:37 AM Dongjin Lee  wrote:

> Hi, slf4j community,
>
> I have a question on slf4j-api's Level definition.
>
> As far as I know, the slf4j community is planning to support the dynamic
> logging level change feature with https://jira.qos.ch/browse/SLF4J-124.
> However, since slf4j-api only defines five levels, omitting `ALL` and `OFF`
> (below), we can't call a method like `logger.setLevel(Level.OFF)` - which
> is available in other logging frameworks.
>
>
> https://github.com/qos-ch/slf4j/blob/master/slf4j-api/src/main/java/org/slf4j/event/EventConstants.java
>
> For example, logback supports seven levels (i.e., five common ones + ALL,
> OFF):
>
>
> https://github.com/qos-ch/logback/blob/master/logback-classic/src/main/java/ch/qos/logback/classic/Level.java
>
> Log4j supports 8 levels (i.e., five common ones + FATAL, ALL, OFF):
>
>
> https://logging.apache.org/log4j/2.x/log4j-api/apidocs/org/apache/logging/log4j/Level.html
>
> Java's official logging level definition is a little bit different, but
> they also support ALL, OFF:
>
> https://docs.oracle.com/javase/7/docs/api/java/util/logging/Level.html
>
> So, in my humble opinion, to make the dynamic logging level change feature
> more complete, slf4j-api is much better to support ALL and OFF levels. What
> do you think?
>
> If you agree and open an issue, I am willing to contribute.
>
> Best,
> Dongjin
>
> --
>
> Dongjin Lee
>
> A hitchhiker in the mathematical world.
>
> github: github.com/dongjinleekr
> keybase: https://keybase.io/dongjinleekr
> linkedin: kr.linkedin.com/in/dongjinleekr
> speakerdeck: speakerdeck.com/dongjin
> ___
> slf4j-user mailing list
> slf4j-user@qos.ch
> http://mailman.qos.ch/mailman/listinfo/slf4j-user
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