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Logging configuration

Read about the use of logging API in Quarkus, configuring logging output, and using logging adapters to unify the output from other logging APIs.

Quarkus uses the JBoss Log Manager logging backend for publishing application and framework logs. Quarkus supports the JBoss Logging API and multiple other logging APIs, seamlessly integrated with JBoss Log Manager. You can use any of the following APIs:

Use JBoss Logging for application logging

When using the JBoss Logging API, your application requires no additional dependencies, as Quarkus automatically provides it.

An example of using the JBoss Logging API to log a message:
import org.jboss.logging.Logger;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

@Path("/hello")
public class ExampleResource {

    private static final Logger LOG = Logger.getLogger(ExampleResource.class);

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        LOG.info("Hello");
        return "hello";
    }
}
While JBoss Logging routes log messages into JBoss Log Manager directly, one of your libraries might rely on a different logging API. In such cases, you need to use a logging adapter to ensure that its log messages are routed to JBoss Log Manager as well.

Get an application logger

In Quarkus, the most common ways to obtain an application logger are by:

Declaring a logger field

With this classic approach, you use a specific API to obtain a logger instance, store it in a static field of a class, and call logging operations upon this instance.

The same flow can be applied with any of the supported logging APIs.

An example of storing a logger instance into a static field by using the JBoss Logging API:
package com.example;

import org.jboss.logging.Logger;

public class MyService {
    private static final Logger log = Logger.getLogger(MyService.class); (1)

    public void doSomething() {
        log.info("It works!"); (2)
    }
}
1 Define the logger field.
2 Invoke the desired logging methods on the log object.

Simplified logging

Quarkus simplifies logging by automatically adding logger fields to classes that use io.quarkus.logging.Log. This eliminates the need for repetitive boilerplate code and enhances logging setup convenience.

An example of simplified logging using static method calls:
package com.example;

import io.quarkus.logging.Log; (1)

class MyService { (2)
    public void doSomething() {
        Log.info("Simple!"); (3)
    }
}
1 The io.quarkus.logging.Log class contains the same methods as JBoss Logging, except that they are static.
2 Note that the class does not declare a logger field. This is because during application build, a private static final org.jboss.logging.Logger field is created automatically in each class that uses the Log API. The fully qualified name of the class that calls the Log methods is used as a logger name. In this example, the logger name would be com.example.MyService.
3 Finally, all calls to Log methods are rewritten to regular JBoss Logging calls on the logger field during the application build.
Only use the Log API in application classes, not in external dependencies. Log method calls that are not processed by Quarkus at build time will throw an exception.

Injecting a configured logger

The injection of a configured org.jboss.logging.Logger logger instance with the @Inject annotation is another alternative to adding an application logger, but is applicable only to CDI beans.

You can use @Inject Logger log, where the logger gets named after the class you inject it to, or @Inject @LoggerName("…​") Logger log, where the logger will receive the specified name. Once injected, you can use the log object to invoke logging methods.

An example of two different types of logger injection:
package com.example;

import org.jboss.logging.Logger;

@ApplicationScoped
class SimpleBean {

   @Inject
   Logger log; (1)

   @LoggerName("foo")
   Logger fooLog; (2)

   public void ping() {
     log.info("Simple!");
     fooLog.info("Goes to _foo_ logger!");
   }
}
1 The FQCN of the declaring class is used as a logger name, for example, org.jboss.logging.Logger.getLogger(SimpleBean.class) will be used.
2 In this case, the name foo is used as a logger name, for example,org.jboss.logging.Logger.getLogger("foo") will be used.
The logger instances are cached internally. Therefore, when a logger is injected, for example, into a @RequestScoped bean, it is shared for all bean instances to avoid possible performance penalties associated with logger instantiation.

Use log levels

Quarkus provides different log levels, which helps developers control the amount of information logged based on the severity of the events.

Log levels used by Quarkus
OFF

A special level to use in configuration in order to turn off logging.

FATAL

A critical service failure or complete inability to service requests of any kind.

ERROR

A significant disruption in a request or the inability to service a request.

WARN

A non-critical service error or problem that may not require immediate correction.

INFO

Service lifecycle events or important related very low-frequency information.

DEBUG

Messages that convey extra information regarding lifecycle or non-request-bound events, useful for debugging.

TRACE

Messages that convey extra per-request debugging information that may be very high frequency.

ALL

A special level to use in configuration to turn on logging for all messages, including custom levels.

You can also configure the following levels for applications and libraries that use java.util.logging:

SEVERE

Same as ERROR.

WARNING

Same as WARN.

CONFIG

Service configuration information.

FINE

Same as DEBUG.

FINER

Same as TRACE.

FINEST

Increased debug output compared to TRACE, which might have a higher frequency.

Table 1. The mapping between the levels
Numerical level value Standard level name Equivalent java.util.logging (JUL) level name

1100

FATAL

Not applicable

1000

ERROR

SEVERE

900

WARN

WARNING

800

INFO

INFO

700

Not applicable

CONFIG

500

DEBUG

FINE

400

TRACE

FINER

300

Not applicable

FINEST

Configure the log level, category, and format

JBoss Logging, integrated into Quarkus, offers a unified configuration for all supported logging APIs through a single configuration file that sets up all available extensions. To adjust runtime logging, modify the application.properties file.

An example of how you can set the default log level to INFO logging and include Hibernate DEBUG logs:
quarkus.log.level=INFO
quarkus.log.category."org.hibernate".level=DEBUG

When you set the log level to below DEBUG, you must also adjust the minimum log level. This setting is either global, using the quarkus.log.min-level configuration property, or per category:

quarkus.log.category."org.hibernate".min-level=TRACE

This sets a floor level for which Quarkus needs to generate supporting code. The minimum log level must be set at build time so that Quarkus can open the door to optimization opportunities where logging on unusable levels can be elided.

An example from native execution:

Setting INFO as the minimum logging level sets lower-level checks, such as isTraceEnabled, to false. This identifies code like if(logger.isDebug()) callMethod(); that will never be executed and mark it as "dead."

If you add these properties on the command line, ensure the " character is escaped properly:

-Dquarkus.log.category.\"org.hibernate\".level=TRACE

All potential properties are listed in the logging configuration reference section.

Logging categories

Logging is configured on a per-category basis, with each category being configured independently. Configuration for a category applies recursively to all subcategories unless there is a more specific subcategory configuration.

The parent of all logging categories is called the "root category." As the ultimate parent, this category might contain a configuration that applies globally to all other categories. This includes the globally configured handlers and formatters.

Example 1. An example of a global configuration that applies to all categories:
quarkus.log.handlers=console,mylog

In this example, the root category is configured to use two handlers: console and mylog.

Example 2. An example of a per-category configuration:
quarkus.log.category."org.apache.kafka.clients".level=INFO
quarkus.log.category."org.apache.kafka.common.utils".level=INFO

This example shows how you can configure the minimal log level on the categories org.apache.kafka.clients and org.apache.kafka.common.utils.

For more information, see Logging configuration reference.

If you want to configure something extra for a specific category, create a named handler like quarkus.log.handler.[console|file|syslog].<your-handler-name>.* and set it up for that category by using quarkus.log.category.<my-category>.handlers.

An example use case can be a desire to use a different timestamp format for log messages which are saved to a file than the format used for other handlers.

For further demonstration, see the outputs of the Attaching named handlers to a category example.

Property Name Por defecto Descripción

quarkus.log.category."<category-name>".level

INFO [1]

The level to use to configure the category named <category-name>. The quotes are necessary.

quarkus.log.category."<category-name>".min-level

DEBUG

The minimum logging level to use to configure the category named <category-name>. The quotes are necessary.

quarkus.log.category."<category-name>".use-parent-handlers

true

Specify whether this logger should send its output to its parent logger.

quarkus.log.category."<category-name>".handlers=[<handler>]

empty [2]

The names of the handlers that you want to attach to a specific category.

The . symbol separates the specific parts in the configuration property. The quotes in the property name are used as a required escape to keep category specifications, such as quarkus.log.category."io.quarkus.smallrye.jwt".level=TRACE, intact.

Root logger configuration

The root logger category is handled separately, and is configured by using the following properties:

Property Name Por defecto Descripción

quarkus.log.level

INFO

The default log level for every log category.

quarkus.log.min-level

DEBUG

The default minimum log level for every log category.

  • The parent category is examined if no level configuration exists for a given logger category.

  • The root logger configuration is used if no specific configurations are provided for the category and any of its parent categories.

Although the root logger’s handlers are usually configured directly via quarkus.log.console, quarkus.log.file and quarkus.log.syslog, it can nonetheless have additional named handlers attached to it using the quarkus.log.handlers property.

Logging format

Quarkus uses a pattern-based logging formatter that generates human-readable text logs by default, but you can also configure the format for each log handler by using a dedicated property.

For the console handler, the property is quarkus.log.console.format.

The logging format string supports the following symbols:

Symbol Summary Descripción

%%

%

Renders a simple % character.

%c

Categoría

Renders the category name.

%C

Source class

Renders the source class name.[3]

%d{xxx}

Date

Renders a date with the given date format string, which uses the syntax defined by java.text.SimpleDateFormat.

%e

Exception

Renders the thrown exception, if any.

%F

Source file

Renders the source file name.[3]

%h

Host name

Renders the system simple host name.

%H

Qualified host name

Renders the system’s fully qualified host name, which may be the same as the simple host name, depending on operating system configuration.

%i

Process ID

Render the current process PID.

%l

Source location

Renders the source location information, which includes source file name, line number, class name, and method name.[3]

%L

Source line

Renders the source line number.[3]

%m

Full Message

Renders the log message plus exception (if any).

%M

Source method

Renders the source method name.[3]

%n

Newline

Renders the platform-specific line separator string.

%N

Process name

Render the name of the current process.

%p

Level

Render the log level of the message.

%r

Relative time

Render the time in milliseconds since the start of the application log.

%s

Simple message

Renders just the log message, with no exception trace.

%t

Thread name

Render the thread name.

%t{id}

Thread ID

Render the thread ID.

%z{<zone name>}

Time zone

Set the time zone of the output to <zone name>.

%X{<MDC property name>}

Mapped Diagnostic Context Value

Renders the value from Mapped Diagnostic Context.

%X

Mapped Diagnostic Context Values

Renders all the values from Mapped Diagnostic Context in format {property.key=property.value}.

%x

Nested Diagnostics context values

Renders all the values from Nested Diagnostics Context in format {value1.value2}.

Alternative console logging formats

Changing the console log format is useful, for example, when the console output of the Quarkus application is captured by a service that processes and stores the log information for later analysis.

JSON logging format

The quarkus-logging-json extension may be employed to add support for the JSON logging format and its related configuration.

  1. Add this extension to your build file as the following snippet illustrates:

    pom.xml
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-logging-json</artifactId>
    </dependency>
    build.gradle
    implementation("io.quarkus:quarkus-logging-json")

    By default, the presence of this extension replaces the output format configuration from the console configuration, and the format string and the color settings (if any) are ignored. The other console configuration items, including those controlling asynchronous logging and the log level, will continue to be applied.

    For some, it will make sense to use humanly readable (unstructured) logging in dev mode and JSON logging (structured) in production mode. This can be achieved using different profiles, as shown in the following configuration.

  2. Disable JSON logging in application.properties for dev and test mode:

    %dev.quarkus.log.console.json=false
    %test.quarkus.log.console.json=false
Configuración

Configure the JSON logging extension using supported properties to customize its behavior.

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Console logging

Tipo

Por defecto

Determine whether to enable the JSON console formatting extension, which disables "normal" console formatting.

Environment variable: QUARKUS_LOG_CONSOLE_JSON

Show more

boolean

true

Enable "pretty printing" of the JSON record. Note that some JSON parsers will fail to read the pretty printed output.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_PRETTY_PRINT

Show more

boolean

false

The date format to use. The special string "default" indicates that the default format should be used.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_DATE_FORMAT

Show more

string

default

The special end-of-record delimiter to be used. By default, newline is used.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_RECORD_DELIMITER

Show more

string

The zone ID to use. The special string "default" indicates that the default zone should be used.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_ZONE_ID

Show more

string

default

The exception output type to specify.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_EXCEPTION_OUTPUT_TYPE

Show more

detailed, formatted, detailed-and-formatted

detailed

Enable printing of more details in the log.

Printing the details can be expensive as the values are retrieved from the caller. The details include the source class name, source file name, source method name, and source line number.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_PRINT_DETAILS

Show more

boolean

false

Override keys with custom values. Omitting this value indicates that no key overrides will be applied.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_KEY_OVERRIDES

Show more

string

Keys to be excluded from the JSON output.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_EXCLUDED_KEYS

Show more

list of string

Additional field value.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_ADDITIONAL_FIELD__FIELD_NAME__VALUE

Show more

string

required

Additional field type specification. Supported types: string, int, and long. String is the default if not specified.

Environment variable: QUARKUS_LOG_CONSOLE_JSON_ADDITIONAL_FIELD__FIELD_NAME__TYPE

Show more

string, int, long

string

File logging

Tipo

Por defecto

Determine whether to enable the JSON console formatting extension, which disables "normal" console formatting.

Environment variable: QUARKUS_LOG_FILE_JSON

Show more

boolean

true

Enable "pretty printing" of the JSON record. Note that some JSON parsers will fail to read the pretty printed output.

Environment variable: QUARKUS_LOG_FILE_JSON_PRETTY_PRINT

Show more

boolean

false

The date format to use. The special string "default" indicates that the default format should be used.

Environment variable: QUARKUS_LOG_FILE_JSON_DATE_FORMAT

Show more

string

default

The special end-of-record delimiter to be used. By default, newline is used.

Environment variable: QUARKUS_LOG_FILE_JSON_RECORD_DELIMITER

Show more

string

The zone ID to use. The special string "default" indicates that the default zone should be used.

Environment variable: QUARKUS_LOG_FILE_JSON_ZONE_ID

Show more

string

default

The exception output type to specify.

Environment variable: QUARKUS_LOG_FILE_JSON_EXCEPTION_OUTPUT_TYPE

Show more

detailed, formatted, detailed-and-formatted

detailed

Enable printing of more details in the log.

Printing the details can be expensive as the values are retrieved from the caller. The details include the source class name, source file name, source method name, and source line number.

Environment variable: QUARKUS_LOG_FILE_JSON_PRINT_DETAILS

Show more

boolean

false

Override keys with custom values. Omitting this value indicates that no key overrides will be applied.

Environment variable: QUARKUS_LOG_FILE_JSON_KEY_OVERRIDES

Show more

string

Keys to be excluded from the JSON output.

Environment variable: QUARKUS_LOG_FILE_JSON_EXCLUDED_KEYS

Show more

list of string

Additional field value.

Environment variable: QUARKUS_LOG_FILE_JSON_ADDITIONAL_FIELD__FIELD_NAME__VALUE

Show more

string

required

Additional field type specification. Supported types: string, int, and long. String is the default if not specified.

Environment variable: QUARKUS_LOG_FILE_JSON_ADDITIONAL_FIELD__FIELD_NAME__TYPE

Show more

string, int, long

string

Syslog logging

Tipo

Por defecto

Determine whether to enable the JSON console formatting extension, which disables "normal" console formatting.

Environment variable: QUARKUS_LOG_SYSLOG_JSON

Show more

boolean

true

Enable "pretty printing" of the JSON record. Note that some JSON parsers will fail to read the pretty printed output.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_PRETTY_PRINT

Show more

boolean

false

The date format to use. The special string "default" indicates that the default format should be used.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_DATE_FORMAT

Show more

string

default

The special end-of-record delimiter to be used. By default, newline is used.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_RECORD_DELIMITER

Show more

string

The zone ID to use. The special string "default" indicates that the default zone should be used.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_ZONE_ID

Show more

string

default

The exception output type to specify.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_EXCEPTION_OUTPUT_TYPE

Show more

detailed, formatted, detailed-and-formatted

detailed

Enable printing of more details in the log.

Printing the details can be expensive as the values are retrieved from the caller. The details include the source class name, source file name, source method name, and source line number.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_PRINT_DETAILS

Show more

boolean

false

Override keys with custom values. Omitting this value indicates that no key overrides will be applied.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_KEY_OVERRIDES

Show more

string

Keys to be excluded from the JSON output.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_EXCLUDED_KEYS

Show more

list of string

Additional field value.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_ADDITIONAL_FIELD__FIELD_NAME__VALUE

Show more

string

required

Additional field type specification. Supported types: string, int, and long. String is the default if not specified.

Environment variable: QUARKUS_LOG_SYSLOG_JSON_ADDITIONAL_FIELD__FIELD_NAME__TYPE

Show more

string, int, long

string

Enabling pretty printing might cause certain processors and JSON parsers to fail.
Printing the details can be expensive as the values are retrieved from the caller. The details include the source class name, source file name, source method name, and source line number.

Log handlers

A log handler is a logging component responsible for the emission of log events to a recipient. Quarkus includes several different log handlers: console, file, and syslog.

The featured examples use com.example as a logging category.

Console log handler

The console log handler is enabled by default, and it directs all log events to the application’s console, usually the system’s stdout.

  • A global configuration example:

    quarkus.log.console.format=%d{yyyy-MM-dd HH:mm:ss} %-5p [%c] (%t) %s%e%n
  • A per-category configuration example:

    quarkus.log.handler.console.my-console-handler.format=%d{yyyy-MM-dd HH:mm:ss} [com.example] %s%e%n
    
    quarkus.log.category."com.example".handlers=my-console-handler
    quarkus.log.category."com.example".use-parent-handlers=false

For details about its configuration, see the console logging configuration reference.

File log handler

To log events to a file on the application’s host, use the Quarkus file log handler. The file log handler is disabled by default, so you must first enable it.

The Quarkus file log handler supports log file rotation.

Log file rotation ensures effective log file management over time by maintaining a specified number of backup log files, while keeping the primary log file up-to-date and manageable.

  • A global configuration example:

    quarkus.log.file.enable=true
    quarkus.log.file.path=application.log
    quarkus.log.file.format=%d{yyyy-MM-dd HH:mm:ss} %-5p [%c] (%t) %s%e%n
  • A per-category configuration example:

    quarkus.log.handler.file.my-file-handler.enable=true
    quarkus.log.handler.file.my-file-handler.path=application.log
    quarkus.log.handler.file.my-file-handler.format=%d{yyyy-MM-dd HH:mm:ss} [com.example] %s%e%n
    
    quarkus.log.category."com.example".handlers=my-file-handler
    quarkus.log.category."com.example".use-parent-handlers=false

For details about its configuration, see the file logging configuration reference.

Syslog log handler

The syslog handler in Quarkus follows the Syslog protocol, which is used to send log messages on UNIX-like systems. It utilizes the protocol defined in RFC 5424.

By default, the syslog handler is disabled. When enabled, it sends all log events to a syslog server, typically the local syslog server for the application.

  • A global configuration example:

    quarkus.log.syslog.enable=true
    quarkus.log.syslog.app-name=my-application
    quarkus.log.syslog.format=%d{yyyy-MM-dd HH:mm:ss} %-5p [%c] (%t) %s%e%n
  • A per-category configuration example:

    quarkus.log.handler.syslog.my-syslog-handler.enable=true
    quarkus.log.handler.syslog.my-syslog-handler.app-name=my-application
    quarkus.log.handler.syslog.my-syslog-handler.format=%d{yyyy-MM-dd HH:mm:ss} [com.example] %s%e%n
    
    quarkus.log.category."com.example".handlers=my-syslog-handler
    quarkus.log.category."com.example".use-parent-handlers=false

For details about its configuration, see the Syslog logging configuration reference.

Add a logging filter to your log handler

Log handlers, such as the console log handler, can be linked with a filter that determines whether a log record should be logged.

To register a logging filter:

  1. Annotate a final class that implements java.util.logging.Filter with @io.quarkus.logging.LoggingFilter, and set the name property:

    An example of writing a filter:
    package com.example;
    
    import io.quarkus.logging.LoggingFilter;
    import java.util.logging.Filter;
    import java.util.logging.LogRecord;
    
    @LoggingFilter(name = "my-filter")
    public final class TestFilter implements Filter {
    
        private final String part;
    
        public TestFilter(@ConfigProperty(name = "my-filter.part") String part) {
            this.part = part;
        }
    
        @Override
        public boolean isLoggable(LogRecord record) {
            return !record.getMessage().contains(part);
        }
    }

    In this example, we exclude log records containing specific text from console logs. The specific text to filter on is not hard-coded; instead, it is read from the my-filter.part configuration property.

    An example of Configuring the filter in application.properties:
    my-filter.part=TEST
  2. Attach the filter to the corresponding handler using the filter configuration property, located in application.properties:

    quarkus.log.console.filter=my-filter

Examples of logging configurations

The following examples show some of the ways in which you can configure logging in Quarkus:

Console DEBUG logging except for Quarkus logs (INFO), no color, shortened time, shortened category prefixes
quarkus.log.console.format=%d{HH:mm:ss} %-5p [%c{2.}] (%t) %s%e%n
quarkus.log.console.level=DEBUG
quarkus.console.color=false

quarkus.log.category."io.quarkus".level=INFO
If you add these properties in the command line, ensure " is escaped. For example, -Dquarkus.log.category.\"io.quarkus\".level=DEBUG.
File TRACE logging configuration
quarkus.log.file.enable=true
# Send output to a trace.log file under the /tmp directory
quarkus.log.file.path=/tmp/trace.log
quarkus.log.file.level=TRACE
quarkus.log.file.format=%d{HH:mm:ss} %-5p [%c{2.}] (%t) %s%e%n
# Set 2 categories (io.quarkus.smallrye.jwt, io.undertow.request.security) to TRACE level
quarkus.log.min-level=TRACE
quarkus.log.category."io.quarkus.smallrye.jwt".level=TRACE
quarkus.log.category."io.undertow.request.security".level=TRACE
As we don’t change the root logger, the console log will only contain INFO or higher level logs.
Named handlers attached to a category
# Send output to a trace.log file under the /tmp directory
quarkus.log.file.path=/tmp/trace.log
quarkus.log.console.format=%d{HH:mm:ss} %-5p [%c{2.}] (%t) %s%e%n
# Configure a named handler that logs to console
quarkus.log.handler.console."STRUCTURED_LOGGING".format=%e%n
# Configure a named handler that logs to file
quarkus.log.handler.file."STRUCTURED_LOGGING_FILE".enable=true
quarkus.log.handler.file."STRUCTURED_LOGGING_FILE".format=%e%n
# Configure the category and link the two named handlers to it
quarkus.log.category."io.quarkus.category".level=INFO
quarkus.log.category."io.quarkus.category".handlers=STRUCTURED_LOGGING,STRUCTURED_LOGGING_FILE
Named handlers attached to the root logger
# configure a named file handler that sends the output to 'quarkus.log'
quarkus.log.handler.file.CONSOLE_MIRROR.enable=true
quarkus.log.handler.file.CONSOLE_MIRROR.path=quarkus.log
# attach the handler to the root logger
quarkus.log.handlers=CONSOLE_MIRROR

Centralized log management

Use a centralized location to efficiently collect, store, and analyze log data from various components and instances of the application.

To send logs to a centralized tool such as Graylog, Logstash, or Fluentd, see the Quarkus Centralized log management guide.

Configure logging for @QuarkusTest

Enable proper logging for @QuarkusTest by setting the java.util.logging.manager system property to org.jboss.logmanager.LogManager.

The system property must be set early on to be effective, so it is recommended to configure it in the build system.

Setting the java.util.logging.manager system property in the Maven Surefire plugin configuration
<build>
  <plugins>
    <plugin>
      <artifactId>maven-surefire-plugin</artifactId>
      <version>${surefire-plugin.version}</version>
      <configuration>
        <systemPropertyVariables>
          <java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager> (1)
          <quarkus.log.level>DEBUG</quarkus.log.level>  (2)
          <maven.home>${maven.home}</maven.home>
        </systemPropertyVariables>
      </configuration>
    </plugin>
  </plugins>
</build>
1 Make sure the org.jboss.logmanager.LogManager is used.
2 Enable debug logging for all logging categories.

For Gradle, add the following configuration to the build.gradle file:

test {
	systemProperty "java.util.logging.manager", "org.jboss.logmanager.LogManager"
}

Use other logging APIs

Quarkus relies on the JBoss Logging library for all the logging requirements.

Suppose you use libraries that depend on other logging libraries, such as Apache Commons Logging, Log4j, or SLF4J. In that case, exclude them from the dependencies and use one of the JBoss Logging adapters.

This is especially important when building native executables, as you could encounter issues similar to the following when compiling the native executable:

Caused by java.lang.ClassNotFoundException: org.apache.commons.logging.impl.LogFactoryImpl

The logging implementation is not included in the native executable, but you can resolve this issue using JBoss Logging adapters.

These adapters are available for popular open-source logging components, as explained in the next chapter.

Add a logging adapter to your application

For each logging API that is not jboss-logging:

  1. Add a logging adapter library to ensure that messages logged through these APIs are routed to the JBoss Log Manager backend.

    This step is unnecessary for libraries that are dependencies of a Quarkus extension where the extension handles it automatically.
    • Apache Commons Logging:

      pom.xml
      <dependency>
          <groupId>org.jboss.logging</groupId>
          <artifactId>commons-logging-jboss-logging</artifactId>
      </dependency>
      build.gradle
      implementation("org.jboss.logging:commons-logging-jboss-logging")
    • Log4j:

      pom.xml
      <dependency>
          <groupId>org.jboss.logmanager</groupId>
          <artifactId>log4j-jboss-logmanager</artifactId>
      </dependency>
      build.gradle
      implementation("org.jboss.logmanager:log4j-jboss-logmanager")
    • Log4j 2:

      pom.xml
      <dependency>
          <groupId>org.jboss.logmanager</groupId>
          <artifactId>log4j2-jboss-logmanager</artifactId>
      </dependency>
      build.gradle
      implementation("org.jboss.logmanager:log4j2-jboss-logmanager")

      Do not include any Log4j dependencies because the log4j2-jboss-logmanager library contains all that is needed to use Log4j as a logging implementation.

    • SLF4J:

      pom.xml
      <dependency>
          <groupId>org.jboss.slf4j</groupId>
          <artifactId>slf4j-jboss-logmanager</artifactId>
      </dependency>
      build.gradle
      implementation("org.jboss.slf4j:slf4j-jboss-logmanager")
  2. Verify whether the logs generated by the added library adhere to the same format as the other Quarkus logs.

Use MDC to add contextual log information

Quarkus overrides the logging Mapped Diagnostic Context (MDC) to improve the compatibility with its reactive core.

Add and read MDC data

To add data to the MDC and extract it in your log output:

  1. Use the MDC class to set the data.

  2. Customize the log format to use %X{mdc-key}.

Let’s consider the following code:

Example with JBoss Logging and io.quarkus.logging.Log
package me.sample;

import io.quarkus.logging.Log;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import org.jboss.logmanager.MDC;

import java.util.UUID;

@Path("/hello/jboss")
public class GreetingResourceJbossLogging {

    @GET
    @Path("/test")
    public String greeting() {
        MDC.put("request.id", UUID.randomUUID().toString());
        MDC.put("request.path", "/hello/test");
        Log.info("request received");
        return "hello world!";
    }
}

If you configure the log format with the following line:

quarkus.log.console.format=%d{HH:mm:ss} %-5p request.id=%X{request.id} request.path=%X{request.path} [%c{2.}] (%t) %s%n

You get messages containing the MDC data:

08:48:13 INFO request.id=c37a3a36-b7f6-4492-83a1-de41dbc26fe2 request.path=/hello/test [me.sa.GreetingResourceJbossLogging] (executor-thread-1) request received

MDC and supported logging APIs

Depending on the API you use, the MDC class is slightly different. However, the APIs are very similar:

  • Log4j 1 - org.apache.log4j.MDC.put(key, value)

  • Log4j 2 - org.apache.logging.log4j.ThreadContext.put(key, value)

  • SLF4J - org.slf4j.MDC.put(key, value)

MDC propagation

In Quarkus, the MDC provider has a specific implementation for handling the reactive context, ensuring that MDC data is propagated during reactive and asynchronous processing.

As a result, you can still access the MDC data in various scenarios:

  • After asynchronous calls, for example, when a REST client returns a Uni.

  • In code submitted to org.eclipse.microprofile.context.ManagedExecutor.

  • In code executed with vertx.executeBlocking().

If applicable, MDC data is stored in a duplicated context, which is an isolated context for processing a single task (request).

Logging configuration reference

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property

Tipo

Por defecto

If enabled and a metrics extension is present, logging metrics are published.

Environment variable: QUARKUS_LOG_METRICS_ENABLED

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boolean

false

The default minimum log level.

Environment variable: QUARKUS_LOG_MIN_LEVEL

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Level

DEBUG

Minimum logging categories

Tipo

Por defecto

The minimum log level for this category. By default, all categories are configured with DEBUG minimum level.

To get runtime logging below DEBUG, e.g., TRACE, adjust the minimum level at build time. The right log level needs to be provided at runtime.

As an example, to get TRACE logging, minimum level needs to be at TRACE, and the runtime log level needs to match that.

Environment variable: QUARKUS_LOG_CATEGORY__CATEGORIES__MIN_LEVEL

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InheritableLevel

inherit

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property

Tipo

Por defecto

The log level of the root category, which is used as the default log level for all categories.

JBoss Logging supports Apache-style log levels:

  • {@link org.jboss.logmanager.Level#FATAL}

  • {@link org.jboss.logmanager.Level#ERROR}

  • {@link org.jboss.logmanager.Level#WARN}

  • {@link org.jboss.logmanager.Level#INFO}

  • {@link org.jboss.logmanager.Level#DEBUG}

  • {@link org.jboss.logmanager.Level#TRACE}

In addition, it also supports the standard JDK log levels.

Environment variable: QUARKUS_LOG_LEVEL

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Level

INFO

The names of additional handlers to link to the root category. These handlers are defined in consoleHandlers, fileHandlers, or syslogHandlers.

Environment variable: QUARKUS_LOG_HANDLERS

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list of string

Console logging

Tipo

Por defecto

If console logging should be enabled

Environment variable: QUARKUS_LOG_CONSOLE_ENABLE

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boolean

true

If console logging should go to System#err instead of System#out.

Environment variable: QUARKUS_LOG_CONSOLE_STDERR

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boolean

false

The log format. Note that this value is ignored if an extension is present that takes control of console formatting (e.g., an XML or JSON-format extension).

Environment variable: QUARKUS_LOG_CONSOLE_FORMAT

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string

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c{3.}] (%t) %s%e%n

The console log level.

Environment variable: QUARKUS_LOG_CONSOLE_LEVEL

Show more

Level

ALL

Specify how much the colors should be darkened. Note that this value is ignored if an extension is present that takes control of console formatting (e.g., an XML or JSON-format extension).

Environment variable: QUARKUS_LOG_CONSOLE_DARKEN

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int

0

The name of the filter to link to the console handler.

Environment variable: QUARKUS_LOG_CONSOLE_FILTER

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string

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_CONSOLE_ASYNC

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boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_CONSOLE_ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_CONSOLE_ASYNC_OVERFLOW

Show more

block, discard

block

File logging

Tipo

Por defecto

If file logging should be enabled

Environment variable: QUARKUS_LOG_FILE_ENABLE

Show more

boolean

false

The log format

Environment variable: QUARKUS_LOG_FILE_FORMAT

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string

%d{yyyy-MM-dd HH:mm:ss,SSS} %h %N[%i] %-5p [%c{3.}] (%t) %s%e%n

The level of logs to be written into the file.

Environment variable: QUARKUS_LOG_FILE_LEVEL

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Level

ALL

The name of the file in which logs will be written.

Environment variable: QUARKUS_LOG_FILE_PATH

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File

quarkus.log

The name of the filter to link to the file handler.

Environment variable: QUARKUS_LOG_FILE_FILTER

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string

The character encoding used

Environment variable: QUARKUS_LOG_FILE_ENCODING

Show more

Charset

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_FILE_ASYNC

Show more

boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_FILE_ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_FILE_ASYNC_OVERFLOW

Show more

block, discard

block

The maximum log file size, after which a rotation is executed.

Environment variable: QUARKUS_LOG_FILE_ROTATION_MAX_FILE_SIZE

Show more

MemorySize

10M

The maximum number of backups to keep.

Environment variable: QUARKUS_LOG_FILE_ROTATION_MAX_BACKUP_INDEX

Show more

int

5

The file handler rotation file suffix. When used, the file will be rotated based on its suffix.

Example fileSuffix: .yyyy-MM-dd

Note: If the suffix ends with .zip or .gz, the rotation file will also be compressed.

Environment variable: QUARKUS_LOG_FILE_ROTATION_FILE_SUFFIX

Show more

string

Indicates whether to rotate log files on server initialization.

You need to either set a max-file-size or configure a file-suffix for it to work.

Environment variable: QUARKUS_LOG_FILE_ROTATION_ROTATE_ON_BOOT

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boolean

true

Syslog logging

Tipo

Por defecto

If syslog logging should be enabled

Environment variable: QUARKUS_LOG_SYSLOG_ENABLE

Show more

boolean

false

The IP address and port of the Syslog server

Environment variable: QUARKUS_LOG_SYSLOG_ENDPOINT

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host:port

localhost:514

The app name used when formatting the message in RFC5424 format

Environment variable: QUARKUS_LOG_SYSLOG_APP_NAME

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string

The name of the host the messages are being sent from

Environment variable: QUARKUS_LOG_SYSLOG_HOSTNAME

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string

Sets the facility used when calculating the priority of the message as defined by RFC-5424 and RFC-3164

Environment variable: QUARKUS_LOG_SYSLOG_FACILITY

Show more

kernel, user-level, mail-system, system-daemons, security, syslogd, line-printer, network-news, uucp, clock-daemon, security2, ftp-daemon, ntp, log-audit, log-alert, clock-daemon2, local-use-0, local-use-1, local-use-2, local-use-3, local-use-4, local-use-5, local-use-6, local-use-7

user-level

Set the SyslogType syslog type this handler should use to format the message sent

Environment variable: QUARKUS_LOG_SYSLOG_SYSLOG_TYPE

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rfc5424, rfc3164

rfc5424

Sets the protocol used to connect to the Syslog server

Environment variable: QUARKUS_LOG_SYSLOG_PROTOCOL

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tcp, udp, ssl-tcp

tcp

If enabled, the message being sent is prefixed with the size of the message

Environment variable: QUARKUS_LOG_SYSLOG_USE_COUNTING_FRAMING

Show more

boolean

false

Set to true to truncate the message if it exceeds maximum length

Environment variable: QUARKUS_LOG_SYSLOG_TRUNCATE

Show more

boolean

true

Enables or disables blocking when attempting to reconnect a org.jboss.logmanager.handlers.SyslogHandler.Protocol#TCP TCP or org.jboss.logmanager.handlers.SyslogHandler.Protocol#SSL_TCP SSL TCP protocol

Environment variable: QUARKUS_LOG_SYSLOG_BLOCK_ON_RECONNECT

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boolean

false

The log message format

Environment variable: QUARKUS_LOG_SYSLOG_FORMAT

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string

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c{3.}] (%t) %s%e%n

The log level specifying what message levels will be logged by the Syslog logger

Environment variable: QUARKUS_LOG_SYSLOG_LEVEL

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Level

ALL

The name of the filter to link to the file handler.

Environment variable: QUARKUS_LOG_SYSLOG_FILTER

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string

The maximum length, in bytes, of the message allowed to be sent. The length includes the header and the message.

If not set, the default value is 2048 when sys-log-type is rfc5424 (which is the default) and 1024 when sys-log-type is rfc3164

Environment variable: QUARKUS_LOG_SYSLOG_MAX_LENGTH

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MemorySize

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_SYSLOG_ASYNC

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boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_SYSLOG_ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_SYSLOG_ASYNC_OVERFLOW

Show more

block, discard

block

Logging categories

Tipo

Por defecto

The log level for this category.

Note that to get log levels below INFO, the minimum level build-time configuration option also needs to be adjusted.

Environment variable: QUARKUS_LOG_CATEGORY__CATEGORIES__LEVEL

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InheritableLevel

inherit

The names of the handlers to link to this category.

Environment variable: QUARKUS_LOG_CATEGORY__CATEGORIES__HANDLERS

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list of string

Specify whether this logger should send its output to its parent Logger

Environment variable: QUARKUS_LOG_CATEGORY__CATEGORIES__USE_PARENT_HANDLERS

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boolean

true

Console handlers

Tipo

Por defecto

If console logging should be enabled

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__ENABLE

Show more

boolean

true

If console logging should go to System#err instead of System#out.

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__STDERR

Show more

boolean

false

The log format. Note that this value is ignored if an extension is present that takes control of console formatting (e.g., an XML or JSON-format extension).

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__FORMAT

Show more

string

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c{3.}] (%t) %s%e%n

The console log level.

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__LEVEL

Show more

Level

ALL

Specify how much the colors should be darkened. Note that this value is ignored if an extension is present that takes control of console formatting (e.g., an XML or JSON-format extension).

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__DARKEN

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int

0

The name of the filter to link to the console handler.

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__FILTER

Show more

string

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__ASYNC

Show more

boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_HANDLER_CONSOLE__CONSOLE_HANDLERS__ASYNC_OVERFLOW

Show more

block, discard

block

File handlers

Tipo

Por defecto

If file logging should be enabled

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ENABLE

Show more

boolean

false

The log format

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__FORMAT

Show more

string

%d{yyyy-MM-dd HH:mm:ss,SSS} %h %N[%i] %-5p [%c{3.}] (%t) %s%e%n

The level of logs to be written into the file.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__LEVEL

Show more

Level

ALL

The name of the file in which logs will be written.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__PATH

Show more

File

quarkus.log

The name of the filter to link to the file handler.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__FILTER

Show more

string

The character encoding used

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ENCODING

Show more

Charset

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ASYNC

Show more

boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ASYNC_OVERFLOW

Show more

block, discard

block

The maximum log file size, after which a rotation is executed.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ROTATION_MAX_FILE_SIZE

Show more

MemorySize

10M

The maximum number of backups to keep.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ROTATION_MAX_BACKUP_INDEX

Show more

int

5

The file handler rotation file suffix. When used, the file will be rotated based on its suffix.

Example fileSuffix: .yyyy-MM-dd

Note: If the suffix ends with .zip or .gz, the rotation file will also be compressed.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ROTATION_FILE_SUFFIX

Show more

string

Indicates whether to rotate log files on server initialization.

You need to either set a max-file-size or configure a file-suffix for it to work.

Environment variable: QUARKUS_LOG_HANDLER_FILE__FILE_HANDLERS__ROTATION_ROTATE_ON_BOOT

Show more

boolean

true

Syslog handlers

Tipo

Por defecto

If syslog logging should be enabled

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__ENABLE

Show more

boolean

false

The IP address and port of the Syslog server

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__ENDPOINT

Show more

host:port

localhost:514

The app name used when formatting the message in RFC5424 format

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__APP_NAME

Show more

string

The name of the host the messages are being sent from

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__HOSTNAME

Show more

string

Sets the facility used when calculating the priority of the message as defined by RFC-5424 and RFC-3164

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__FACILITY

Show more

kernel, user-level, mail-system, system-daemons, security, syslogd, line-printer, network-news, uucp, clock-daemon, security2, ftp-daemon, ntp, log-audit, log-alert, clock-daemon2, local-use-0, local-use-1, local-use-2, local-use-3, local-use-4, local-use-5, local-use-6, local-use-7

user-level

Set the SyslogType syslog type this handler should use to format the message sent

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__SYSLOG_TYPE

Show more

rfc5424, rfc3164

rfc5424

Sets the protocol used to connect to the Syslog server

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__PROTOCOL

Show more

tcp, udp, ssl-tcp

tcp

If enabled, the message being sent is prefixed with the size of the message

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__USE_COUNTING_FRAMING

Show more

boolean

false

Set to true to truncate the message if it exceeds maximum length

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__TRUNCATE

Show more

boolean

true

Enables or disables blocking when attempting to reconnect a org.jboss.logmanager.handlers.SyslogHandler.Protocol#TCP TCP or org.jboss.logmanager.handlers.SyslogHandler.Protocol#SSL_TCP SSL TCP protocol

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__BLOCK_ON_RECONNECT

Show more

boolean

false

The log message format

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__FORMAT

Show more

string

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c{3.}] (%t) %s%e%n

The log level specifying what message levels will be logged by the Syslog logger

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__LEVEL

Show more

Level

ALL

The name of the filter to link to the file handler.

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__FILTER

Show more

string

The maximum length, in bytes, of the message allowed to be sent. The length includes the header and the message.

If not set, the default value is 2048 when sys-log-type is rfc5424 (which is the default) and 1024 when sys-log-type is rfc3164

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__MAX_LENGTH

Show more

MemorySize

Indicates whether to log asynchronously

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__ASYNC

Show more

boolean

false

The queue length to use before flushing writing

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__ASYNC_QUEUE_LENGTH

Show more

int

512

Determine whether to block the publisher (rather than drop the message) when the queue is full

Environment variable: QUARKUS_LOG_HANDLER_SYSLOG__SYSLOG_HANDLERS__ASYNC_OVERFLOW

Show more

block, discard

block

Log cleanup filters - internal use

Tipo

Por defecto

The message prefix to match

Environment variable: QUARKUS_LOG_FILTER__FILTERS__IF_STARTS_WITH

Show more

list of string

inherit

The new log level for the filtered message. Defaults to DEBUG.

Environment variable: QUARKUS_LOG_FILTER__FILTERS__TARGET_LEVEL

Show more

Level

DEBUG

About the MemorySize format

A size configuration option recognises string in this format (shown as a regular expression): [0-9]+[KkMmGgTtPpEeZzYy]?. If no suffix is given, assume bytes.


1. Some extensions may define customized default log levels for certain categories, in order to reduce log noise by default. Setting the log level in configuration will override any extension-defined log levels.
2. By default, the configured category gets the same handlers attached as the one on the root logger.
3. Format sequences which examine caller information may affect performance

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