Hi Amanda, I am crossposting this to dev@logging.apache.org. Please answer to that mailing list.
On Tue, 6 Aug 2024 at 01:05, Amanda Liu <as...@terpmail.umd.edu> wrote: > The reason I want a custom appender is to pretty print the JSON log objects > produced by JsonTemplateLayout, to make it more readable. I see in the log4j > docs that JSON pretty print is supported in JsonLayout, but not > JsonTemplateLayout. I don't want to use JsonLayout, since it's deprecated and > doesn't support some other features that JSONTemplateLayout has. > > Is there any strong reason why JsonTemplateLayout does not support JSON > pretty print? Or could I contribute to the JsonTemplateLayout file in the > log4j repo to add this feature? (here: > https://github.com/apache/logging-log4j2/blob/a884e991c1a551cb321b2efed770a15fbc55aa2b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/JsonTemplateLayout.java). > This would resolve my issue, and I think other log4j JsonTemplateLayout > users may be interested in the pretty print feature. There is no special reason why `JsonTemplateLayout` does not support pretty print. It was simply never implemented. Currently JTL only writes to a small `JsonWriter`[1] class through `TemplateResolver.resolve()`[2]. This could be easily generalized (probably in `3.x`) by replacing `JsonWriter` with an interface, to support multiple serialization formats. There is already a JIRA issue for that (see LOG4J2-3082[0]). Admittedly this requires quite some work, but it is within the grasp of a semester-long student project or Google Summer of Code. If you are willing to contribute such a feature, we can always assist you with the Log4j-related details. Piotr BTW: I added more info about shading applications that use Log4j Core to our documentation[3] [0] https://issues.apache.org/jira/browse/LOG4J2-3082 [1] https://javadoc.io/static/org.apache.logging.log4j/log4j-layout-template-json/2.19.0/org/apache/logging/log4j/layout/template/json/util/JsonWriter.html [2] https://javadoc.io/static/org.apache.logging.log4j/log4j-layout-template-json/2.19.0/org/apache/logging/log4j/layout/template/json/resolver/TemplateResolver.html#resolve-V-org.apache.logging.log4j.layout.template.json.util.JsonWriter- [3] https://github.com/apache/logging-log4j2/blob/2.x/src/site/antora/modules/ROOT/pages/faq.adoc#how-do-i-create-a-single-jar-application-containing-log4j-core
