Delay UDP connect until first log event emission

[clear1]

v1.15.0
If network is absent and level has value OFF then rise java.net.SocketException: Network is unreachable: connect
(1.14.1 all work fine)

logback.xml:

<appender name="gelf-udp" class="biz.paluch.logging.gelf.logback.GelfLogbackAppender">
        <host>udp:10.129.106.150</host>
        <port>2514</port>
        <version>1.1</version>
        <originHost>develop</originHost>
        <facility>GELF</facility>
        <extractStackTrace>true</extractStackTrace>
        <filterStackTrace>true</filterStackTrace>
        <includeLocation>true</includeLocation>
        <mdcProfiling>true</mdcProfiling>
        <timestampPattern>yyyy-MM-dd HH:mm:ss,SSS</timestampPattern>
        <maximumMessageSize>2048</maximumMessageSize>
        <includeFullMdc>true</includeFullMdc>
        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
            <level>OFF</level>
        </filter>
    </appender>

Error:

30-01-2023 18:01:12.364 [main] ERROR o.s.boot.SpringApplication.reportFailure - Application run failed
java.lang.IllegalStateException: java.lang.IllegalStateException: Logback configuration error detected:
ERROR in biz.paluch.logging.gelf.logback.GelfLogbackAppender[gelf-udp] - Network is unreachable: connect java.net.SocketException: Network is unreachable: connect
at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:344)
at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:298)
at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:131)
at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:85)
at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:66)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:120)
at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:114)
at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:65)
at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:344)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:302)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295)
at com.etp.tm.kdh.iop.ServerApplication.main(ServerApplication.java:37)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:65)
Caused by: java.lang.IllegalStateException: Logback configuration error detected:

[mp911de]

Can you get hold of the stack trace for the SocketException? Generally, log system startup with networked senders requires network connectivity as the sockets are starting early.

[clear1]

If I disable all network adapters then rise exception. But how to get stacktrace?

[mp911de]

The exception is truncated at Caused by: java.lang.IllegalStateException: Logback configuration error detected:. Alternatively, you can set a breakpoint in your debugger in the LoggingApplicationListener class in the initializeSystem method.

[clear1]

Hello!
GelfLogbackAppender create instance of GelfUDPSender which is an implementation of GelfSender.
look at method connect () when try to create
DatagramChannel connect = ((DatagramChannel)this.channel()).connect(inetSocketAddress); rised a SocketException which stored in reportError.
Then LogbackLoggingSystem->loadConfiguration method, the statuses of all elements of the logging context are checked, this SocketException is detected and an IllegalStateException is thrown, which crashes the entire application.
Isn't it more logical in this case to turn off the appender, rather than destroy everything?

[mp911de]

Isn't it more logical in this case to turn off the appender, rather than destroy everything?

This is an assumption that varies across projects. Logback has a lifecycle mechanism to start and stop individual appenders. If the orchestrating system would consider these means properly and leave failed appenders as is, then you would not have that kind of issue.

[mp911de]

Similar to the TCP sender, we can delay the connect of the UDP sender until receiving the first log event.