mariocairone / log4j2-prop-lookup

A log4j2 lookup plugin to load properties from Yaml and properties files

log4j2-prop-lookup

A log4j2 plugin to enable properties lookup from a configurable list of property files.

The file can be either .yaml or ..properties file. If a file has a .yaml extension the properties will be loaded using the yaml property loader. Any other extensions will use the property file properties loader.

Installation

To enable the plugin, include the following dependency in the pom.xml

<dependency>
    <groupId>com.mariocairone</groupId>
    <artifactId>log4j2-prop-lookup</artifactId>
    <version>1.0.1</version>
</dependency> 

Configuration

The plugin is configured using the following properties:

name	values	description	required
prop.files	String	A comma separated list of file paths	true
prop.dir	String	The base directory for all the files in the list	false

---

NOTE

the filePaths must be relative to the classpath root.

If the optional prop.dir properties is present its value will be used as prefix for each filePath.

The com.mariocairone.log4j2 must be declared in the log4j2.xml configuration file.

---

Example

A common scenario is to customize the log4j2 configuration with different properties for different environments. We can have an Http appender sending the logs to a sandbox logstash instance for non production deployments and to a different instance for the production deployment. Or we want to customize our layout with properties that are specific for an environment.

to do that I have to create a properties file for each environment:

sandbox.yaml

environment:
  name: "Sandbox"
logstash:
  url: "http://mysandbox.host:8080"

production.yaml

environment:
  name: "Production"
logstash:
  url: "http://myproduction.host:8080"

log4j.xml

I can then use a system properties to select the properties file based on the environment.

<Configuration packages="com.mariocairone.log4j2">
    <Properties>
     <Property name="prop.files">${sys:mule.env}.yaml</Property>
    </Properties>
  ...
    <Http name="http" url="${prop:logstash.url}" >
        <Property name="Content-Type" value="application/json" />
        <JsonLayout complete="true" properties="true" >
          <KeyValuePair key="environment" value="${prop:environment.name}"/>
        </JsonLayout>
    </Http> 

log4j2-prop-lookup's Issues

Bug: Only last files is loaded into properties

Due to a bug only the last processed files properties will be made available by the plugin.

private void load() {
  if (configuration != null) {
    if (!loaded) {
      StrLookup resolver = configuration.getStrSubstitutor().getVariableResolver();
      final String dir = resolver.lookup(LOG4J2_DIR_PROPERTY_NAME);
      String files = resolver.lookup(LOG4J2_FILES_PROPERTY_NAME);
				
      LOGGER.debug("Properties File: " + files);
      Arrays.asList(files.split(",")).forEach(fileName -> {
        String filePath = getFilePath(dir,fileName);
        PropertiesLoader loader = PropertiesLoaderFactory.createPropertiesLoader(filePath);
        this.properties = loader.getProperties();
      });
    loaded = true;
     }
}

in the load method, when properties are loaded from another file, then the loaded properties need to be merged with the properties already loaded.

...
this.properties.putAll(loader.getProperties());
...