system-designer/example-log4j2-appender

An example showing the progressive development of a Log4J 2.x appender

This project is an example showing the progressive development of a Log4J 2.x appender, layout, and lookup. It exists to support this post on my website.

Each stage of development is recorded as a separate commit:

• stage-1
  The basic appender, which writes output to StdOut.

• stage-2
  Adds a configuration property, repeats, which will write the log message multiple times.

• stage-3
  Uses a Builder object to configure the appender.

• stage-4
  Creates a configuration interface that's implemented by the Builder, so that the appender doesn't have to unpack configuration.

• stage-5
  Demonstration of the appender life-cycle, using another custom appender that reports each life-cycle method invocation.

• stage-6
  Adds support for layouts that provide a header and footer.

• stage-7
  Implements an example layout.

• stage-8
  Updates the example layout to support Lookups (and use them internally).

• stage-9
  Implements a custom Lookup for hostname and process ID.

• stage-10
  Adds unit tests.

Each of the stage names above is a tag that you can use to check out the project at that stage.

All of the stages are buildable using Maven.