Jody Garnett created LOG4J2-3469:
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Summary: Override configuration file properties and appenders with
programmatic configuration
Key: LOG4J2-3469
URL: https://issues.apache.org/jira/browse/LOG4J2-3469
Project: Log4j 2
Issue Type: New Feature
Components: Configuration, Configurators, Core
Affects Versions: 2.17.2
Reporter: Jody Garnett
Attachments: DEFAULT_LOGGING.xml
The documentation covers both [Initialize Log4j by Combining Configuration File
with Programmatic
Configuration|https://logging.apache.org/log4j/2.x/manual/customconfig.html#Hybrid]
and [Programmatically Modifying the Current Configuration after
Initialization|https://logging.apache.org/log4j/2.x/manual/customconfig.html#Programmatically_Modifying_the_Current_Configuration_after_Initialization].
However both these techniques are limited as to what they can accomplish:
* MyXMLConfiguration.doConfigure() is shown adding an appender, via addLogger
method
* A custom configuration super.setup() method is shown using
config.addLogger() and then ctx.updateLoggers().
My challenge is to programatically update the configuration to:
* Override logfile output location, either directly modifying appender, or
modifying config property used by appender.
* Optionally Filter out any RollingFileAppender or FileAppender appenders
* Optionally suppress (filter out) any Console loggers if asked
I am seeking an api used to pre-process configuration if one is available.
Candidates:
*MyXMLConfiguration.setup()* prior to super.setup(): Unclear how easy/safe it
is to to modify node structure directly? Is this what is intended?
{code:java}
public void setup() {
for( Node child : rootNode.getChildren()){
if ("Properties".equals(child.getName())){
for( Node property : child.getChildren() ){
if( property.getAttributes().containsKey("name") &&
property.getAttributes().get("name").equals("GEOSERVER_LOG_LOCATION")) {
// override value with current GEOSERVER_LOG_LOCATION
property.setValue("foo.log");
}
}
}
}
super.setup();
}{code}
*MyXMLConfiguration.doConfigure()* before super.doConfigure(): should be able
to modify ``rootNode`` and make any changes required. Unclear how easy/safe it
is to to modify node structure directly?
*MyXMLConfiguration.doConfigure()* after super.doConfigure(): is too late:
- Can only append add loggers and appenders
- Modifications to config.getProperties() are not reflected in appender
configuration.
- Modifications to existing appenders cannot be accomplished
- In the past when using a fluent / builder API there is an option to
jump-start a builder with the configuration of an existing object. This
approach would allow a builder to be loaded with an existing appender; revised,
and a new appender generated as a replacement.
*MyXMLConfiguration.*{*}preConfigure(Node){*} allows xml to be rewritten
just-in-time:
{code:java}
@Overrideprotected void preConfigure(Node node) {
if( !node.isRoot() && node.getName().equals("Property")){
if( node.getAttributes().containsKey("name") &&
node.getAttributes().get("name").equals("GEOSERVER_LOG_LOCATION")) {
// override value with current GEOSERVER_LOG_LOCATION
node.setValue("foo.log");
}
}
super.preConfigure(node);
} {code}
For reference see attached {*}DEFAULT_LOGGING.xml{*}.
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