Awesome

vertx-web-accesslog

An access log implementation to be used in vertx web routes.

Inspired and with intention to be compliant with

• Apache HTTP Server mod_log_config module (http://httpd.apache.org/docs/2.4/en/mod/mod_log_config.html)

• W3C Extended Log File Format (http://www.w3.org/TR/WD-logfile.html)

The main idea is to have an event based logging, with the possibility (but not enforcing you to do so) to directly export a log event natively to a target system, and not having to first write and persist it to a file and then read and parse it again from there like eg ELK is doing it. The drawback that those kind of solutions have is performance but even more issues like recognizing complete stacktraces etc. The ElasticSearch Appender is the only appender for now that takes advantage of those benefits. However you are free of course to use a traditional ELK setup style and just write your output to either console or a specific logfile - and let eg logstash take over from there.

Key facts

• Zero dependencies (apart of vertx-web obviously)
• Easily extendable and customizable
• Small memory footprint

Technical Usage

The artefact is published on maven central.

Just add it as a dependency to your project (gradle example)

dependencies {
	compile 'com.romanpierson:vertx-web-accesslog:1.7.0'
}

Compatibility with Vertx core

Previous versions are listed for completeness only and not supported anymore.

Access Log Pattern Configuration

The logger supports mixing of both log formats and is also designed to easily add custom log elements

Define your custom AccessLogElement

You can easily create your custom implementation of AccessLogElement by creating your own element class implementing AccessLogElement interface. The available AccessLogElement types are discovered by ServiceLoader, so just add to your resources a file like this and inside list your AccessLogElement classes

META-INF
 services
  com.romanpierson.vertx.web.accesslogger.configuration.element.AccessLogElement

As ServiceLoader SPI is intented to work with objects unfortunately your AccessLogElement implementation requires a parameter less constructor.

In order that the pattern resolver is able to resolve your new element against a pattern you have to implement your resolving condition by implementing findInRawPatternInternal(rawPattern) method.

To facility this and to avoid boilerplate code there are static helpers in PatternResolver that simplifies that a lot.

Redefine existing elements with your custom one

By defining your custom element using same pattern as an existing one shipped with this library it will have preference over the predefined one.

Appenders

Appenders are basically a way to send the log data to one (or multiple) backends. This ships with a set of (hopefully) useful appenders but you can create your custom appenders in a very easy way.

Available Appenders

Custom Appenders

You can easily write your own appender doing

Write your own CustomAppender class that must

• implement Appender Interface
• have a public constructor taking a JsonObject instance holding the configuration

AccessLoggerProducerVerticle

This verticle is responsible for receiving the raw data, formatting it based on the AccessLogElements configured and forwards the resulting data to the registered Appenders (by calling Appender.push).

There is one worker instance of AccessLoggerProducerVerticle per vertx context started if you put configuration value isAutoDeployProducerVerticle to true (by default it is). If you prefer to manage the deployment of that verticle byself set the property to false.

Usage

This describes the basic usage. More specific info eg about the different appenders can be found on the links.

Configure route

Just put an instance of AccessLogHandler as first route handler.

Router router = Router.router(vertx);

JsonObject config = .... load or create your configuration json

router.route().handler(AccessLoggerHandler.create(config));

As configuration is now done by plain JsonObject its very simple to use and inject configuration eg by yaml, see as an example ServerSetupStarter

configurations:
  - identifier: accesslog-formatted
    logPattern: '%{}t %D "cs-uri"'
    appenders:
      - appenderClassName : com.romanpierson.vertx.web.accesslogger.appender.console.impl.ConsoleAppender
  - identifier: accesslog-plain
    logPattern: "%{msec}t %D cs-uri"
    appenders:
      - appenderClassName : com.romanpierson.vertx.web.accesslogger.appender.console.impl.ConsoleAppender

Supported log elements

Currently those elements are supported

Static values

For static values you should prefer to use the %{value}static element. In case you have an appender like ConsoleAppender or LoggingAppender that writes its output via the resolved pattern you can also put such static values directly into the logpattern as it will just stay as non resolved. However for other appenders like ElasticSearchAppender one you need to explicitly define the element.

Empty behavior

The default way for elements where no actual value can be evaluated is to return a NULL value. This way the appender is able to translate this into an empty string or eg skip the value if we index towards a solution like ElasticSearch.

Changelog

Detailed changelog can be found here.

Demo Playground

A sample project that shows usage of this (and other related features) can be found here.