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https://issues.apache.org/jira/browse/LOG4J2-3138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17405696#comment-17405696
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Volkan Yazici commented on LOG4J2-3138:
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LOG4J2-3082 addresses this to a certain extent. There {{JsonTemplateLayout}}
will allow falling back to external JSON serializers, e.g., Jackson. Note that
this is only relevant while serializing messages and MDC, this doesn't enable
you to customize the JSON structure {{LogEvent}} is rendered to. In its current
form, {{LogEvent}} JSON structure is described by the JSON template. Letting
people to pass this structure by annotations on a POJO is indeed an interesting
idea, yet I am not inclined to go this route due to following concerns:
* We will need to duplicate every single JTL functionality along with their
configuration logic in annotations. This translates to at least 2-3 dozens of
annotations. I would rather see a real world use case before pushing such a
change to the code base.
* Almost every Log4j configuration lives in a separate file – this is aligned
with the idea of providing the JSON template in a separate file.
* One might argue that they need to provide the JSON template programmatically.
That is still perfectly possible:
{code:java}
// writeJson(Object) can be implemented either using Jackson or JTL's
JsonWriter.
String eventTemplate = writeJson(Map.of(
"ex_stacktrace", Map.of(
"$resolver", "exception",
"field", "stackTrace",
"stringified", true)));
JsonTemplateLayout layout = JsonTemplateLayout
.newBuilder()
.setConfiguration(configuration)
.setStackTraceEnabled(true)
.setEventTemplate(eventTemplate)
.build();
{code}
* I personally think Log4j suffers from a feature creep when it comes to JSON:
3 competing JSON layouts ({{GelfLayout}}, {{JsonLayout}},
{{JsonTemplateLayout}}), many independent JSON utilities
({{StringBuilders.escapeJson()}}, {{MapMessageJsonFormatter}}, JTL's
{{Json\{Reader,Writer\}}}), etc. I wanted to remove all this bloat in 3.x and
settle with JTL, but rejected due to backward compatibility concerns. I think
the proposed {{EnhancedJsonLayout}} will only worsen the situation.
> Define a custom model for a json layout for creating custom json logs output
> ----------------------------------------------------------------------------
>
> Key: LOG4J2-3138
> URL: https://issues.apache.org/jira/browse/LOG4J2-3138
> Project: Log4j 2
> Issue Type: New Feature
> Components: Core
> Reporter: Alireza Vahedi
> Assignee: Volkan Yazici
> Priority: Major
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> In current json layout user can not define a custom json structure for json
> logs. For such purpose they have to define new layout. Why new layout is
> required when just the model structure of json has been changed?
> I think we need a enhanced json layout that gets some class as targetÂ
> structure for generating json of logs, and user can configure it in log4j2
> xml configurable file.
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