Improve LogstashJsonEventLayoutV1

[vy]

Improve LogstashJsonEventLayoutV1

[vy]

• Regarding renaming source_host to host, exception.exception_class to exception.class, and thread_name to thread, I intentionally picked those field names to be aligned with the official logstash/log4j-jsonevent-layout project. (Am I missing something here?) In case of a particular need, you can provide your own JSON template.
• Providing an interface for variable substitution makes totally sense. I will check how can I do that.
• Extending MDC and NDC maps can be a little bit challenging given the lack of a proper JSON schema processor solution. What do you think of adding two new properties: mdc_extension and ndc_extension? I can merge these with mdc and ndc maps respectively prior to logging.
• About filtering MDC and NDC maps, would a simple mdcKeyPattern and ndcKeyPattern having a regex statement address your case? As you can imagine, these will definitely add quite some regex processing overhead to the logging too.

[gquintana]

Thanks Volkan,

• Extending context: what about an "LDC" map (logger DC) at the Logger level, and copy it in a separate JSON field instead of merging maps? Another idea: be able to add custom fields in particular type/tags fields in order to be able to process logs differently on Logstash depending on matching appender (at the moment having a different layout for each appender is painful).
• Filtering MDC/NDC: a list of authorized fields is enough for my usecase. This means iterating over this list and fetch values from the map instead of iterating over the map entries. Another idea: make filtering plugable (a predicate over map entries).

[vy]

• Extending context: From your description I understood that you just want to have a custom map similar to MDC/NDC. Right? If so, why not creating a map entry (i.e. "ldc": {"foo": "bar", "baz": "moo"}) in a custom JSON template? Am I misinterpreting your explanation?
• Filtering MDC/NDC: Do you want to filter on keys, values, or both?

[vy]

Just pushed v0.4 to Maven Central. Added mdcKeyPattern and ndcPattern configuration parameters. Further, Log4j 2.x Lookup support is integrated.

[gquintana]

Thanks. I'll reopen a new issue to be able to get environnement vars/system properties in template.

[vy]

@gquintana, I've already released that feature. Let me know if it doesn't work for you.