Dynamic configuration

This page contains example of configuring Log4j2 (including Tjahzi) in a dynamic way. E.g. you might want to enable some part of configuration based on environment property.

Using ConfigurationBuilder

This mode of configuration if described in log4j docs. Below follows excerpt from this test.

Click to expand

ConfigurationBuilder<BuiltConfiguration> builder = ConfigurationBuilderFactory.newConfigurationBuilder();

builder.setConfigurationName("loki-programmatically");
builder.setStatusLevel(Level.ALL);
builder.setPackages("pl.tkowalcz.tjahzi.log4j2");

builder.add(
    builder.newRootLogger(Level.ALL)
        .add(builder.newAppenderRef("Loki"))
);

AppenderComponentBuilder lokiAppenderBuilder = builder.newAppender("Loki", "Loki")
    .addAttribute("host", "${sys:loki.host}")
    .addAttribute("port", "${sys:loki.port}")
    .add(
        builder
            .newFilter("ThresholdFilter", Filter.Result.ACCEPT, Filter.Result.DENY)
            .addAttribute("level", "ALL")
    )
    .add(
        builder
            .newLayout("PatternLayout")
            .addAttribute("pattern", "%X{tid} [%t] %d{MM-dd HH:mm:ss.SSS} %5p %c{1} - %m%n%exception{full}")
    )
    .addComponent(
        builder.newComponent("Header")
            .addAttribute("name", "server")
            .addAttribute("value", "127.0.0.1")
    )
    .addComponent(
        builder.newComponent("Label")
            .addAttribute("name", "server")
            .addAttribute("value", "127.0.0.1")
    );
    
builder.add(lokiAppenderBuilder);
Configurator.reconfigure(builder.build());

You can also verify resulting configuration using builder.writeXmlConfiguration(...);

Using RoutingAppender

The RoutingAppender evaluates LogEvents and then routes them to a subordinate Appender.

Example (courtesy of https://github.com/tkowalcz/tjahzi/issues/64#issuecomment-880207646):

<Routing name="ROUTER">
    <Routes pattern="$${env:LOG_TO:-CONSOLE}">
        <Route ref="LOKI" key="LOKI" />
        <Route ref="CONSOLE" key="CONSOLE" />
    </Routes>
</Routing>