vertx-log-transformer

Transforms log content received over the Vert.x EventBus and writes the transformed logs to the configured destination.

To use the vertx-log-transformer, the log content has to be sent over the EventBus to the configured address. To select the log transform strategy, the transform strategy name has to be provided in the DeliveryOptions headers as property with the configured strategyHeader value.

An example of how to send the logs to the vertx-log-transformer can be seen below:

DeliveryOptions options = new DeliveryOptions();
options.setHeaders(new CaseInsensitiveHeaders().add("strategyHeader", "myLogTransformStrategy"));

Vertx.vertx().eventBus().publish("swisspush.logtransformer", "log content to transform", options);

When no (or an unknown) log transform strategy is provided, the DoNothingTransformStrategy is applied which logs the original (not transformed) log input !

Write custom log transform strategies

To implement a custom log transform strategy create a new Class implementing TransformStrategy interface or extending the AbstractTransformStrategy class.

The DoNothingTransformStrategy is a very simple example of a log transform strategy:

public class DoNothingTransformStrategy implements TransformStrategy {

    private Vertx vertx;

    public DoNothingTransformStrategy(Vertx vertx) {
        this.vertx = vertx;
    }

    @Override
    public void transformLog(String logToTransform, Handler<AsyncResult<List<String>>> resultHandler) {
        vertx.executeBlocking(future -> future.complete(Collections.singletonList(logToTransform)), resultHandler);
    }
}

By extending the AbstractTransformStrategy class, basic functionality like error handling and JSON parsing are available.

When writing a new custom log transform strategy also extend the findTransformStrategy(MultiMap headers) method of DefaultTransformStrategyFinder class (or write a new one) to match the provided strategy name (strategyHeader) to the strategy implementation.

Example:

if("MyNewCustomLogTransformStrategy".equalsIgnoreCase(headers.get("strategyHeader"))){
    return new MyNewCustomLogTransformStrategy();
}

Configuration

The following configuration values are available:

{
    "address": "swisspush.logtransformer",      // The event bus address to listen on
    "loggerName": "LogTransformerLogger",       // The name of the logger to write the logfile to
    "strategyHeader": "transformStrategy"       // The name of the header property containing the strategy
}

Configuration util

The configurations have to be passed as JsonObject to the module. For a simplyfied configuration the ConfigurationBuilder can be used.

Example:

Configuration config = Configuration.with()
        .address("some_eventbus_address")
        .loggerName("MyCustomLogger")
        .strategyHeader("customStrategy")
        .build();

JsonObject json = config.asJsonObject();

Log4j configuration

The vertx-log-transfomer module requires a configured loggerName (default is 'LogTransformerLogger'). This loggerName has to be used in the log4j configuration.

A log4j configuration example:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration debug="false"
    xmlns:log4j='http://jakarta.apache.org/log4j/'>

    <loggername="LogTransformerLogger"additivity="false">
        <appender-refref="LogTransformerFileAppender"/>
    </logger>

    <appendername="LogTransformerFileAppender"class="org.apache.log4j.DailyRollingFileAppender">
        <paramname="File"value="/path/to/logfiles/logTransformer.log"/>
        <paramname="Encoding"value="UTF-8"/>
        <paramname="Append"value="true"/>
        <layoutclass="org.apache.log4j.EnhancedPatternLayout">
            <paramname="ConversionPattern" value="%m%n"/>
        </layout>
    </appender>

</log4j:configuration>

Use gradle with alternative repositories

As standard the default maven repositories are set. You can overwrite these repositories by setting these properties (-Pproperty=value):

• repository this is the repository where resources are fetched
• uploadRepository the repository used in uploadArchives
• repoUsername the username for uploading archives
• repoPassword the password for uploading archives