log4j2Metrics not work when Log4j2 reconfigured

[ddavidzhang]

Describe the bug
Now，log4j2Metrics is registed when server starting up. But when Log4j2 LoggerContexted is reconfigured because of config being changed, the filter will not work.

Environment

• Micrometer version : 1.9.15 and 1.12.3
• Micrometer registry : prometheus
• OS: ALL
• Java version: jdk 8 and jdk 21

To Reproduce
How to reproduce the bug:
After a spring server starts up, we change some log4j2's config, logging level for example and Log4j2's reconfigure will be triggered. After this, the filter in log4j2Metrics will not work.

Expected behavior
log4j2Metrics always work

[shakuzen]

I'm not familiar with how the details of how reconfiguring works. Could you share a snippet of code demonstrating what is being done? Ideally if it can be put in a unit test that is minimal (i.e. doesn't involve Spring), we can add it to our tests when we address this and ensure it works now and going forward. I wonder if there is a way we can register a callback that is run when reconfiguration happens.

[ddavidzhang]

I just change some config (any) at Nacos, and that will trigger a RefreshEvent of Spring. Then, the logging system of Spring will load loadConfiguration again.
I'm also not familiar with how the details of how reconfiguring works.
The "LoggerContext.setConfiguration" is called, or "LoggerContext.reconfigure" is called.
The following are the stack:

setConfiguration:601, LoggerContext (org.apache.logging.log4j.core)
start:285, LoggerContext (org.apache.logging.log4j.core)
start:87, AsyncLoggerContext (org.apache.logging.log4j.core.async)
loadConfiguration:228, Log4J2LoggingSystem (org.springframework.boot.logging.log4j2)
loadConfiguration:194, Log4J2LoggingSystem (org.springframework.boot.logging.log4j2)
initializeWithSpecificConfig:66, AbstractLoggingSystem (org.springframework.boot.logging)
initialize:57, AbstractLoggingSystem (org.springframework.boot.logging)
initialize:170, Log4J2LoggingSystem (org.springframework.boot.logging.log4j2)
reinitializeLoggingSystem:168, PropertySourceBootstrapConfiguration (org.springframework.cloud.bootstrap.config)
doInitialize:148, PropertySourceBootstrapConfiguration (org.springframework.cloud.bootstrap.config)
initialize:110, PropertySourceBootstrapConfiguration (org.springframework.cloud.bootstrap.config)
applyInitializers:604, SpringApplication (org.springframework.boot)
prepareContext:373, SpringApplication (org.springframework.boot)
run:306, SpringApplication (org.springframework.boot)
run:164, SpringApplicationBuilder (org.springframework.boot.builder)
addConfigFilesToEnvironment:78, LegacyContextRefresher (org.springframework.cloud.context.refresh)
updateEnvironment:56, LegacyContextRefresher (org.springframework.cloud.context.refresh)
refreshEnvironment:101, ContextRefresher (org.springframework.cloud.context.refresh)
refresh:94, ContextRefresher (org.springframework.cloud.context.refresh)
handle:72, RefreshEventListener (org.springframework.cloud.endpoint.event)
onApplicationEvent:61, RefreshEventListener (org.springframework.cloud.endpoint.event)
doInvokeListener:178, SimpleApplicationEventMulticaster (org.springframework.context.event)
invokeListener:171, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:145, SimpleApplicationEventMulticaster (org.springframework.context.event)
publishEvent:421, AbstractApplicationContext (org.springframework.context.support)
publishEvent:378, AbstractApplicationContext (org.springframework.context.support)
innerReceive:118, NacosContextRefresher$1 (com.alibaba.cloud.nacos.refresh)
receiveConfigInfo:40, AbstractSharedListener (com.alibaba.nacos.api.config.listener)
lambda$safeNotifyListener$1:334, CacheData (com.alibaba.nacos.client.config.impl)
run:-1, 1979102041 (com.alibaba.nacos.client.config.impl.CacheData$$Lambda$1931)
call:511, Executors$RunnableAdapter (java.util.concurrent)
run$$$capture:266, FutureTask (java.util.concurrent)
run:-1, FutureTask (java.util.concurrent)
 - Async stack trace
<init>:151, FutureTask (java.util.concurrent)
newTaskFor:87, AbstractExecutorService (java.util.concurrent)
submit:111, AbstractExecutorService (java.util.concurrent)
safeNotifyListener:365, CacheData (com.alibaba.nacos.client.config.impl)
checkListenerMd5:285, CacheData (com.alibaba.nacos.client.config.impl)
refreshContentAndCheck:454, ClientWorker (com.alibaba.nacos.client.config.impl)
refreshContentAndCheck:436, ClientWorker (com.alibaba.nacos.client.config.impl)
access$600:95, ClientWorker (com.alibaba.nacos.client.config.impl)
executeConfigListen:800, ClientWorker$ConfigRpcTransportClient (com.alibaba.nacos.client.config.impl)
lambda$startInternal$2:704, ClientWorker$ConfigRpcTransportClient (com.alibaba.nacos.client.config.impl)
call:511, Executors$RunnableAdapter (java.util.concurrent)
run$$$capture:266, FutureTask (java.util.concurrent)
run:-1, FutureTask (java.util.concurrent)
 - Async stack trace
<init>:151, FutureTask (java.util.concurrent)
<init>:209, ScheduledThreadPoolExecutor$ScheduledFutureTask (java.util.concurrent)
schedule:532, ScheduledThreadPoolExecutor (java.util.concurrent)
startInternal:697, ClientWorker$ConfigRpcTransportClient (com.alibaba.nacos.client.config.impl)
start:136, ConfigTransportClient (com.alibaba.nacos.client.config.impl)
<init>:428, ClientWorker (com.alibaba.nacos.client.config.impl)
<init>:83, NacosConfigService (com.alibaba.nacos.client.config)
newInstance0:-2, NativeConstructorAccessorImpl (sun.reflect)
newInstance:62, NativeConstructorAccessorImpl (sun.reflect)
newInstance:45, DelegatingConstructorAccessorImpl (sun.reflect)
newInstance:423, Constructor (java.lang.reflect)
createConfigService:43, ConfigFactory (com.alibaba.nacos.api.config)
createConfigService:44, NacosFactory (com.alibaba.nacos.api)
createConfigService:55, NacosConfigManager (com.alibaba.cloud.nacos)
<init>:43, NacosConfigManager (com.alibaba.cloud.nacos)
registerConfigManager:198, NacosConfigDataLocationResolver (com.alibaba.cloud.nacos.configdata)
resolveProfileSpecific:153, NacosConfigDataLocationResolver (com.alibaba.cloud.nacos.configdata)
lambda$resolve$2:120, ConfigDataLocationResolvers (org.springframework.boot.context.config)
resolve:126, ConfigDataLocationResolvers (org.springframework.boot.context.config)
resolve:119, ConfigDataLocationResolvers (org.springframework.boot.context.config)
resolve:107, ConfigDataLocationResolvers (org.springframework.boot.context.config)
resolve:106, ConfigDataImporter (org.springframework.boot.context.config)
resolve:98, ConfigDataImporter (org.springframework.boot.context.config)
resolveAndLoad:86, ConfigDataImporter (org.springframework.boot.context.config)
withProcessedImports:116, ConfigDataEnvironmentContributors (org.springframework.boot.context.config)
processWithProfiles:311, ConfigDataEnvironment (org.springframework.boot.context.config)
processAndApply:232, ConfigDataEnvironment (org.springframework.boot.context.config)
postProcessEnvironment:102, ConfigDataEnvironmentPostProcessor (org.springframework.boot.context.config)
postProcessEnvironment:94, ConfigDataEnvironmentPostProcessor (org.springframework.boot.context.config)
onApplicationEnvironmentPreparedEvent:102, EnvironmentPostProcessorApplicationListener (org.springframework.boot.env)
onApplicationEvent:87, EnvironmentPostProcessorApplicationListener (org.springframework.boot.env)
doInvokeListener:178, SimpleApplicationEventMulticaster (org.springframework.context.event)
invokeListener:171, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:145, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:133, SimpleApplicationEventMulticaster (org.springframework.context.event)
environmentPrepared:85, EventPublishingRunListener (org.springframework.boot.context.event)
lambda$environmentPrepared$2:66, SpringApplicationRunListeners (org.springframework.boot)
forEach:1259, ArrayList (java.util)
doWithListeners:120, SpringApplicationRunListeners (org.springframework.boot)
doWithListeners:114, SpringApplicationRunListeners (org.springframework.boot)
environmentPrepared:65, SpringApplicationRunListeners (org.springframework.boot)
prepareEnvironment:343, SpringApplication (org.springframework.boot)
run:301, SpringApplication (org.springframework.boot)
run:164, SpringApplicationBuilder (org.springframework.boot.builder)
bootstrapServiceContext:195, BootstrapApplicationListener (org.springframework.cloud.bootstrap)
onApplicationEvent:114, BootstrapApplicationListener (org.springframework.cloud.bootstrap)
onApplicationEvent:77, BootstrapApplicationListener (org.springframework.cloud.bootstrap)
doInvokeListener:178, SimpleApplicationEventMulticaster (org.springframework.context.event)
invokeListener:171, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:145, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:133, SimpleApplicationEventMulticaster (org.springframework.context.event)
environmentPrepared:85, EventPublishingRunListener (org.springframework.boot.context.event)
lambda$environmentPrepared$2:66, SpringApplicationRunListeners (org.springframework.boot)
forEach:1259, ArrayList (java.util)
doWithListeners:120, SpringApplicationRunListeners (org.springframework.boot)
doWithListeners:114, SpringApplicationRunListeners (org.springframework.boot)
environmentPrepared:65, SpringApplicationRunListeners (org.springframework.boot)
prepareEnvironment:343, SpringApplication (org.springframework.boot)
run:301, SpringApplication (org.springframework.boot)
run:1303, SpringApplication (org.springframework.boot)
run:1292, SpringApplication (org.springframework.boot)
main:24, AuthorizationApplication (com.springboot.cloud.sysadmin.authorization)

`

[ddavidzhang]

I'm not familiar with how the details of how reconfiguring works. Could you share a snippet of code demonstrating what is being done? Ideally if it can be put in a unit test that is minimal (i.e. doesn't involve Spring), we can add it to our tests when we address this and ensure it works now and going forward. I wonder if there is a way we can register a callback that is run when reconfiguration happens.

I can try to make some tests about this

[ddavidzhang]

Adding a listener of PropertyChangeEvent may be a solution

[ddavidzhang]

I'm not familiar with how the details of how reconfiguring works. Could you share a snippet of code demonstrating what is being done? Ideally if it can be put in a unit test that is minimal (i.e. doesn't involve Spring), we can add it to our tests when we address this and ensure it works now and going forward. I wonder if there is a way we can register a callback that is run when reconfiguration happens.

I can try to make some tests about this

I add some code as below，and it works for my project. The problem is involved by Spring's Refresh Event, I cannot give some unit tests.

@Component
public class Log4J2MetricConfig {
    MeterRegistry meterRegistry;
    Log4j2Metrics binder;

    public Log4J2MetricConfig(MeterRegistry meterRegistry, Log4j2Metrics binder) {
        this.meterRegistry = meterRegistry;
        this.binder = binder;
    }

    @EventListener
    public void handleContextRefreshEvent(RefreshEvent refreshedEvent) {
        if ("Refresh Nacos config".equals(refreshedEvent.getEventDesc())) {
            binder.bindTo(meterRegistry);
        }
    }
}