src/site/antora/modules/ROOT/pages/manual/_properties.adoc

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[#SystemProperties]
= Global configuration properties

Log4j contains a simple configuration properties sub-system that aggregates data from multiple property sources, such as Java https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html[System Properties] and https://docs.oracle.com/javase/tutorial/essential/environment/env.html[Environment Variables].
See <<property-sources>> for a complete list of supported sources

Global configuration properties are used by Log4j in the following situations:

* to finely tune global Log4j API and Log4j Core services that are independent of the configuration file,
* to change the default values of attributes used in a configuration file.

Since Log4j 2.10 all the property names follow a common naming scheme:

----
log4j2.camelCasePropertyName
----

except the environment variables, which follow the:

----
LOG4J_CAMEL_CASE_PROPERTY_NAME
----

convention.

[NOTE]
====
If a `log4j2.system.properties` file is available on the classpath its contents are sourced into Java system properties at Log4j startup.
====

[WARNING]
====
To provide backward compatibility with versions older than 2.10 a certain number of additional property names is also supported using a fuzzy matching algorithm.

In case of problems with the properties sub-system, make sure that your application does not use property names with the following case-insensitive prefixes:

* `asyncLogger`,
* `disableThreadContext`,
* `isThreadContext`,
* `org.apache.logging.log4j`

and that all the properties names that start with `log4j` use the normalized form provided by the tables below.
====

== Meta configuration properties

In order to rapidly optimize Log4j Core for a particular usage, you can use the following properties:

.Meta configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.isWebapp]]`log4j2.isWebapp`

(`LOG4J_IS_WEBAPP`)
| `true` if the https://jakarta.ee/specifications/servlet/6.0/apidocs/jakarta.servlet/jakarta/servlet/servlet[Servlet] class on classpath
| Setting this property to `true` switches Log4j Core into  "Web application mode" (_"Web-app mode"_).

In this mode Log4j is optimized to work in a Servlet container.

This mode is incompatible with <<log4j2.enableThreadlocals>>.

| [[log4j2.enableThreadlocals]]`log4j2.enableThreadlocals`

(`LOG4J_ENABLE_THREADLOCALS`)
| `!log4j2.isWebapp`
| Setting this property to `true` switches Log4j Core into  "garbage-free mode" (_"GC-free mode"_).

In this mode Log4j uses `ThreadLocal`s for object pooling to prevent object allocations.

This mode is incompatible with <<log4j2.isWebapp>>.

|===

== Log4j API properties

The services included in the `log4j-api` module can be configured exclusively through configuration properties.

=== LoaderUtil

The `LoaderUtil` class is used to load classes specified by the user using a fully qualified class name.
Therefore, its configuration influences all other services.

It has only one configuration property:

.LoaderUtil configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.ignoreTcl]]`log4j2.ignoreTcl`

(`LOG4J_IGNORE_TCL`)
| `false`
|
If `true`, classes are only loaded using the same classloader that loaded Log4j.

Otherwise, an attempt is made to load classes with the current thread's context class loader before falling back to the default class loader.

|===

=== Provider

The runtime classpath of an application **should** contain only a single implementation of the Log4j API.
In the particular case, when multiple implementations are present, you can select a specific implementation by setting the value of `log4j2.provider` (or environment variable `LOG4J_PROVIDER`) to the fully qualified name of the chosen provider.
See link:../javadoc/log4j-api/org/apache/logging/log4j/spi/Provider[Provider] for details.

[NOTE]
====
For backward compatibility users can specify the link:../javadoc/log4j-api/org/apache/logging/log4j/spi/LoggerContextFactory[LoggerContextFactory] and link:../javadoc/log4j-api/org/apache/logging/log4j/spi/ThreadContextMap[ThreadContextMap] services independently using the `log4j2.loggerContextFactory` and <<log4j2.threadContextMap>> properties respectively.
====

=== Status Logger

Log4j contains an internal logging mechanism called `StatusLogger` that is used by all Log4j components.
By default, the status logger only reports errors on the standard error stream, but you can configure it using the following properties.

.Status logger configuration
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.debug]]`log4j2.debug`

(`LOG4J_DEBUG`)
| false
| If set to a value different from `false`, sets the level of the status logger to `TRACE` overriding any other system property.

| [[log4j2.statusEntries]]`log4j2.statusEntries`

(`LOG4J_STATUS_ENTRIES`)
| 0
| Specifies the number of status logger entries to cache.
Once the limit is reached newer entries will overwrite the oldest ones.

| [[log4j2.statusLoggerLevel]]`log4j2.statusLoggerLevel`

(`LOG4J_STATUS_LOGGER_LEVEL`)
| ERROR
| Specifies the level of the status logger.
Can be overridden by <<log4j2.debug>> or the `status` property of the current configuration file.

| [[log4j2.statusLoggerDateFormat]]`log4j2.statusLoggerDateFormat`

(`LOG4J_STATUS_LOGGER_DATE_FORMAT`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/java/time/format/DateTimeFormatter.html#ISO_INSTANT[DateTimeFormatter#ISO_INSTANT]
| Sets the https://docs.oracle.com/javase/{java-target-version}/docs/api/java/time/format/DateTimeFormatter.html[DateTimeFormatter] pattern used by status logger to format dates.

| [[log4j2.statusLoggerDateFormatZone]]`log4j2.statusLoggerDateFormatZone`

(`LOG4J_STATUS_LOGGER_DATE_FORMAT_ZONE`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/java/time/ZoneId.html#systemDefault()[ZoneId#systemDefault()]
| Sets the timezone id used by status logger. See https://docs.oracle.com/javase/{java-target-version}/docs/api/java/time/ZoneId.html[ZoneId] for the accepted formats.

|===

=== Simple logger

The simple logger implementation contained in `log4j-api` can be configured using these properties:

.Simple logger configuration
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.simplelogLevel]]`log4j2.simplelogLevel`

(`LOG4J_SIMPLELOG_LEVEL`)
| ERROR
| Default level for new logger instances.

| [[log4j2.simplelog.loggerName.level]]`log4j2.simplelog.&lt;loggerName&gt;.level`

(`LOG4J_SIMPLELOG_&lt;LOGGER_NAME&gt;_LEVEL`)
| value of <<log4j2.simplelogLevel>>
| Log level for a logger instance named `<loggerName>`.

| [[log4j2.simplelogShowContextMap]]`log4j2.simplelogShowContextMap`

(`LOG4J_SIMPLELOG_SHOW_CONTEXT_MAP`)
| false
| If `true`, the full thread context map is included in each log message.

| [[log4j2.simplelogShowlogname]]`log4j2.simplelogShowlogname`

(`LOG4J_SIMPLELOG_SHOWLOGNAME`)
| false
| If `true`, the logger name is included in each log message.

| [[log4j2.simplelogShowShortLogname]]`log4j2.simplelogShowShortLogname`

(`LOG4J_SIMPLELOG_SHOW_SHORT_LOGNAME`)
| true
| If `true`, only the last component of a logger name is included in each log message.

| [[log4j2.simplelogShowdatetime]]`log4j2.simplelogShowdatetime`

(`LOG4J_SIMPLELOG_SHOWDATETIME`)
| false
| If `true`, a timestamp is included in each log message.

| [[log4j2.simplelogDateTimeFormat]]`log4j2.simplelogDateTimeFormat`

(`LOG4J_SIMPLELOG_DATE_TIME_FORMAT`)
| `yyyy/MM/dd HH:mm:ss:SSS zzz`
| Date-time format to use. Ignored if <<log4j2.simplelogShowdatetime>> is `false`.

| [[log4j2.simplelogLogFile]]`log4j2.simplelogLogFile`

(`LOG4J_SIMPLELOG_LOG_FILE`)
| System.err
a| Specifies the output stream used by all loggers:

* `System.err` logs to the standard error output stream,
* `System.out` logs to the standard output stream,
* any other value is interpreted as a file name.

|===

[#simple-logger-thread-context]
=== Thread context (Simple Logger)

The behavior of the `ThreadContext` class can be fine-tuned using the following properties.

[WARNING]
====
These configuration properties are only used by the Log4j Core and Simple Logger implementations of Log4j API.

The `log4j-to-slf4j` logging bridge delegates `ThreadContext` calls to the SLF4J https://slf4j.org/api/org/slf4j/MDC.html[MDC] class.

The `log4j-to-jul` logging bridge ignores all `ThreadContext` method calls.
====

.Thread context configuration
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.disableThreadContext]]`log4j2.disableThreadContext`

(`LOG4J_DISABLE_THREAD_CONTEXT`)
| false
| If `true`, the `ThreadContext` stack and map are disabled.

| [[log4j2.disableThreadContextStack]]`log4j2.disableThreadContextStack`

(`LOG4J_DISABLE_THREAD_CONTEXT_STACK`)
| false
| If `true`, the `ThreadContext` stack is disabled.

| [[log4j2.disableThreadContextMap]]`log4j2.disableThreadContextMap`

(`LOG4J_DISABLE_THREAD_CONTEXT_MAP`)
| false
| If `true`, the `ThreadContext` map is disabled.

| [[log4j2.threadContextMap]]`log4j2.threadContextMap`

(`LOG4J_THREAD_CONTEXT_MAP`)
| `WebApp`

(GC-free mode: `CopyOnWrite`)
a| Fully specified class name of a custom `ThreadContextMap` implementation class or one of the predefined constants:

* `NoOp`: to disable the thread context,
* `WebApp`: a web application-safe implementation, that only binds JRE classes to `ThreadLocal` to prevent memory leaks,
* `CopyOnWrite`: a copy-on-write implementation,
* `GarbageFree`: a garbage-free implementation.

| [[isThreadContextMapInheritable]]`log4j2.isThreadContextMapInheritable`

(`LOG4J_IS_THREAD_CONTEXT_MAP_INHERITABLE`)
| false
| If `true` uses an `InheritableThreadLocal` to copy the thread context map to newly created threads.

| [[log4j2.garbagefreeThreadContextMap]]`log4j2.garbagefreeThreadContextMap`

(`LOG4J_GARBAGEFREE_THREAD_CONTEXT_MAP`)
| false
| If set to `true` selects a garbage-free thread context map implementation.
Requires <<log4j2.enableThreadlocals>> to be also `true`.

|===

== Log4j Core

While the only required configuration of the `log4j-core` library is provided by the xref:manual/configuration_new.adoc#configuration-file[configuration file], the library offers many configuration properties that can be used to finely tune the way it works.

=== Async components

The behavior of all three async components (`AsyncLogger`, `AsyncLoggerConfig` and `AsyncAppender`) can be tuned using these properties:

.Common async component configuration
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.formatMsgAsync]]`log4j2.formatMsgAsync`

(`LOG4J_FORMAT_MSG_ASYNC`)
| false
| If `false`, Log4j will make sure the message is formatted in the caller thread, otherwise the formatting will occur on the asynchronous thread.

**Remark**: messages annotated with link:../javadoc/log4j-api/org/apache/logging/log4j/message/AsynchronouslyFormattable[AsynchronouslyFormattable] will be formatted on the async thread regardless of this setting.

| [[log4j2.asyncQueueFullPolicy]]`log4j2.asyncQueueFullPolicy`

(`LOG4J_ASYNC_QUEUE_FULL_POLICY`)
| `Default`
a| Determines the link:../javadoc/log4j-core/org/apache/logging/log4j/core/async/AsyncQueueFullPolicy[AsyncQueueFullPolicy] to use when the underlying async component cannot keep up with the logging rate and the queue is filling up.

It accepts the following values:

* `Default`: blocks the calling thread until the event can be added to the queue.

* `Discard`: when the queue is full, it drops the events whose level is equal or less than the threshold level (see <<log4j2.discardThreshold>>).

* the fully qualified class name of a custom implementation

| [[log4j2.discardThreshold]]`log4j2.discardThreshold`

(`LOG4J_DISCARD_THRESHOLD`)
| `INFO`
| Determines the threshold level used by a `Discard` queue full policy.
Log events whose level is equal or less specific than the threshold level will be discarded during a queue full event.
See also <<log4j2.asyncQueueFullPolicy>>.

|===

==== `AsyncLogger`

Additional properties supported by `AsyncLogger` are documented in the xref:manual/async.adoc#SysPropsAllAsync[System Properties to configure all asynchronous loggers] table.

==== `AsyncLoggerConfig`

Additional properties supported by `AsyncLoggerConfig` are documented in the xref:manual/async.adoc#SysPropsMixedSync-Async[System Properties to configure mixed asynchronous and normal loggers] table.

=== Context selector

The link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ContextSelector[ContextSelector] component specifies the strategy used by Log4j to create new logger contexts.
The choice of `ContextSelector` determines in particular:

* how loggers are divided among logger contexts.
See xref:manual/logsep.adoc[Log Separation] for details.

* the `Logger` implementation used by Log4j Core.
See xref:manual/async.adoc[Async Logging] as an example of this usage.

.Context selector configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.contextSelector]]`log4j2.contextSelector`

(`LOG4J_CONTEXT_SELECTOR`)
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector[ClassLoaderContextSelector]
a|
Specifies the fully qualified class name of the `ContextSelector` implementation to use.

The implementations available by default are:

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/BasicContextSelector[org.apache.logging.log4j
.core.selector.BasicContextSelector]: creates a single logger context and synchronous loggers,

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/async/BasicAsyncLoggerContextSelector[org.apache.logging.log4j.core.async.BasicAsyncLoggerContextSelector]: creates a single logger context and xref:manual/async.adoc[asynchronous loggers],

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector[org.apache.logging.log4j.core.selector.ClassLoaderContextSelector]: creates a separate logger context per classloader and synchronous loggers,

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/async/AsyncLoggerContextSelector[org.apache.logging.log4j.core.async.AsyncLoggerContextSelector]: creates a separate logger context per classloader and xref:manual/async.adoc[asynchronous loggers],

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/osgi/BundleContextSelector[org.apache.logging.log4j.core.osgi.BundleContextSelector]: creates a separate logger context per OSGi bundle and synchronous loggers,

* link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/JndiContextSelector[org.apache.logging.log4j.core.selector.JndiContextSelector]: creates loggers contexts based on a JNDI lookup and synchronous loggers.
See xref:manual/webapp.adoc#use-jndi-context-selector[Web application]] for details.

|===

=== Configuration factory

Since configuration factories are used to parse the configuration file, they can **only** be configured through global configuration properties.

[WARNING]
====
Log4j Core supports both local and remote configuration files.
If a remote configuration file is used, its transport must be secured.
See <<transport-security>> for details.
====

.Configuration factory properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.configurationFactory]]`log4j2.configurationFactory`

(`LOG4J_CONFIGURATION_FACTORY`)
|
|
Specifies the fully qualified class name of the **preferred** link:../javadoc/log4j-core/org/apache/logging/log4j/core/config/ConfigurationFactory[ConfigurationFactory] to use.

Log4j will attempt to use the provided configuration factory before any other factory implementation.

| [[log4j2.configurationFile]]`log4j2.configurationFile`

(`LOG4J_CONFIGURATION_FILE`)
| xref:manual/configuration.adoc#AutomaticConfiguration[automatically detected]
a|
Specifies a comma-separated list of URIs or file paths to Log4j 2 configuration files.

If a relative URL is provided, it is interpreted as:

* path to a file, if the file exists,
* a classpath resource otherwise.

See also xref:manual/configuration.adoc#AutomaticConfiguration[Automatic Configuration].

| [[log4j2.level]]`log4j2.level`

(`LOG4J_LEVEL`)
| `ERROR`
a|
Specifies the level of the root logger if:

* the default configuration is used,

* or the configuration file does not specify a level for the root logger.

| [[log4j2.mergeStrategy]]`log4j2.mergeStrategy`

(`LOG4J_MERGE_STRATEGY`)
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/config/composite/DefaultMergeStrategy[DefaultMergeStrategy]
|
Specifies the fully qualified class name of the link:../javadoc/log4j-core/org/apache/logging/log4j/core/config/composite/MergeStrategy[MergeStrategy] implementation used to merge multiple configuration files into one.

|===

=== Garbage Collection

.GC properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description


| [[log4j2.enableDirectEncoders]]`log4j2.enableDirectEncoders`

(`LOG4J_ENABLE_DIRECT_ENCODERS`)
| `true`
|
If `true`, garbage-aware layouts will directly encode log events into https://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html[ByteBuffers] provided by appenders.

This prevents the creation temporary multiple `String` and `char[]` temporary objects.

| [[log4j2.initialReusableMsgSize]]`log4j2.initialReusableMsgSize`

(`LOG4J_INITIAL_REUSABLE_MSG_SIZE`)
| 128
| In GC-free mode, this property determines the initial size of the reusable ``StringBuilder``s used by link:../javadoc/log4j-api/org/apache/logging/log4j/message/ReusableMessage[ReusableMessages] for formatting purposes.

| [[log4j2.maxReusableMsgSize]]`log4j2.maxReusableMsgSize`

(`LOG4J_MAX_REUSABLE_MSG_SIZE`)
| 518
| In GC-free mode, this property determines the maximum size of the reusable ``StringBuilder``s used by link:../javadoc/log4j-api/org/apache/logging/log4j/message/ReusableMessage[ReusableMessages] for formatting purposes.

The default value allows is equal to `2 &times; (2 &times; log4j.initialReusableMsgSize + 2) + 2` and allows the
``StringBuilder`` to be resized twice by the current JVM resize algorithm.

| [[log4j2.layoutStringBuilderMaxSize]]`log4j2.layout{zwsp}StringBuilderMaxSize`

(`LOG4J_LAYOUT_{zwsp}STRING_BUILDER_MAX_SIZE`)
| 2048
| This property determines the maximum size of the reusable ``StringBuilder``sused to format link:../javadoc/log4j-core/org/apache/logging/log4j/core/LogEvent[LogEvents].

| [[log4j2.unboxRingbufferSize]]`log4j2.unboxRingbufferSize`

(`LOG4J_UNBOX_RINGBUFFER_SIZE`)
| 32
|
The link:../javadoc/log4j-api/org/apache/logging/log4j/util/Unbox[Unbox] utility class can be used by users to format primitive values without incurring in the boxing allocation cost.

This property specifies the maximum number of primitive arguments to a log message that will be cached and usually does not need to be changed.

|===

=== JANSI

If the https://fusesource.github.io/jansi/[JANSI] library is on the runtime classpath of the application, the following property can be used to control its usage:

.JANSI properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.skipJansi]]`log4j2.skipJansi`

(`LOG4J_SKIP_JANSI`)
| `true`
a| If the following conditions are satisfied:

* Log4j runs on Windows,
* this property is set to `false`,

Log4j will use the JANSI library to color the output of the console appender.

|===

=== JNDI

Due to the inherent security problems of https://docs.oracle.com/javase/tutorial/jndi/overview/[JNDI], its usage in Log4j is restricted to the `java:` protocol.

Moreover, each JNDI usage must be **explicitly** enabled by the user through the following configuration properties.

.JMX properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.enableJndiContextSelector]]`log4j2.enableJndiContextSelector`

(`LOG4J_ENABLE_JNDI_CONTEXT_SELECTOR`)
| `false`
|
When `true` the `JndiContextSelector` is enabled for the `java:` protocol.
See xref:manual/webapp.adoc#use-jndi-context-selector[Web application] for more details.

| [[log4j2.enableJndiJdbc]]`log4j2.enableJndiJdbc`

(`LOG4J_ENABLE_JNDI_JDBC`)
| `false`
| When `true`, a Log4j JDBC Appender can use JNDI to retrieve a https://docs.oracle.com/javase/8/docs/api/javax/sql/DataSource.html[DataSource] using the `java:` protocol.

| [[log4j2.enableJndiJms]]`log4j2.enableJndiJms`

(`LOG4J_ENABLE_JNDI_JMS`)
| `false`
| When `true`, a Log4j JMS Appender can use JNDI to retrieve the necessary components using the `java:` protocol.

| [[log4j2.enableJndiLookup]]`log4j2.enableJndiLookup`

(`LOG4J_ENABLE_JNDI_LOOKUP`)
| `false`
| When `true`, the Log4j JNDI Lookup can use the `java:` protocol.

|===

=== JMX

.JMX properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.disableJmx]]`log4j2.disableJmx`

(`LOG4J_DISABLE_JMX`)
| `true`
|
If `false`, Log4j configuration objects like ``LoggerContext``s, ``Appender``s, ``Logger``s, etc.
will be instrumented with ``MBean``s and can be remotely monitored and managed.

| [[log4j2.jmxNotifyAsync]]`log4j2.jmxNotifyAsync`

(`LOG4J_JMX_NOTIFY_ASYNC`)
| `true`

(Web-app mode: `false`)
|
If `true`, Log4j's JMX notifications are sent from a separate background thread, otherwise they are sent from the caller thread.

|===

[#log4j-core-thread-context]
=== Thread context (Log4j Core)

Log4j Core supports the same properties as Simple Logger for the configuration of the thread context.
See <<simple-logger-thread-context>> for more details.

[#transport-security]
=== Transport security

Since configuration files can be used to load arbitrary classes into a Log4j Core `Configuration`, users need to ensure that all the configuration elements come from trusted sources (cf. link:/security#threat-common-config-sources[Thread model] for more information).

In order to protect the user Log4j disables the `http` URI scheme by default and provides several configuration options to ensure secure transport of configuration files:

:jsse-default-keystores: https://docs.oracle.com/en/java/javase/21/security/java-secure-socket-extension-jsse-reference-guide.html#GUID-7D9F43B8-AABF-4C5B-93E6-3AFB18B66150

.Transport security properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.configurationAllowedProtocols]]`log4j2.configuration{zwsp}AllowedProtocols`

(`LOG4J_CONFIGURATION_{zwsp}ALLOWED_PROTOCOLS`)
| file, https, jar
|
A comma separated list of URL protocols that may be used to load any kind of configuration source.

To completely prevent accessing the configuration via the Java https://docs.oracle.com/javase/8/docs/api/java/net/URL.html[URL class] specify a value of `_none`.

// TODO: What about 'jar:http:'?

| [[log4j2.configurationAuthorizationProvider]]`log4j2.configuration{zwsp}AuthorizationProvider`

(`LOG4J_CONFIGURATION_{zwsp}AUTHORIZATION_PROVIDER`)
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/BasicAuthorizationProvider[BasicAuthorizationProvider]
| The fully qualified class name of the link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/AuthorizationProvider[AuthorizationProvider] implementation to use with `http` and `https` URL protocols.

3+h| HTTP Basic authentication

| [[log4j2.configurationAuthorizationEncoding]]`log4j2.configuration{zwsp}AuthorizationEncoding`

(`LOG4J_CONFIGURATION_{zwsp}AUTHORIZATION_ENCODING`)
| UTF-8
| The encoding used in Basic Authentication (cf. https://datatracker.ietf.org/doc/html/rfc7617[RFC 7617]).

| [[log4j2.configurationPassword]]`log4j2.configurationPassword`

(`LOG4J_CONFIGURATION_PASSWORD`)
|
| The password to use in HTTP Basic authentication.

If used in conjunction with <<log4j2.configurationPasswordDecryptor>> the contents of this variable are
interpreted by the decryptor.

| [[log4j2.configurationPasswordDecryptor]]`log4j2.configuration{zwsp}PasswordDecryptor`

(`LOG4J_CONFIGURATION_{zwsp}PASSWORD_DECRYPTOR`)
|
| Fully qualified class name of an implementation of link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/PasswordDecryptor[PasswordDecryptor] to use for the value of the <<log4j2.configurationPassword>> property.

By default, the literal value of the password is used.

| [[log4j2.configurationUsername]]`log4j2.configurationUsername`

(`LOG4J_CONFIGURATION_USERNAME`)
|
| The username used in HTTP Basic authentication.

3+h| TLS server authentication properties

| [[log4j2.trustStoreLocation]]`log4j2.trustStoreLocation`

(`LOG4J_TRUST_STORE_LOCATION`)
| see link:{jsse-default-keystores}[Default Java trust store]
| The location of the trust store.

| [[log4j2.trustStorePassword]]`log4j2.trustStorePassword`

(`LOG4J_TRUST_STORE_PASSWORD`)
|
| The password for the trust store.

| [[log4j2.trustStorePasswordFile]]`log4j2.trustStore{zwsp}PasswordFile`

(`LOG4J_TRUST_STORE_{zwsp}PASSWORD_FILE`)
|
| The name of a file that contains the password for the trust store.

| [[log4j2.trustStorePasswordEnvironmentVariable]]`log4j2.trustStore{zwsp}PasswordEnvironmentVariable`

(`LOG4J_TRUST_STORE_{zwsp}PASSWORD_ENVIRONMENT_VARIABLE`)
|
| The name of the environment variable that contains password for the trust store.

| [[log4j2.trustStoreType]]`log4j2.trustStoreType`

(`LOG4J_TRUST_STORE_TYPE`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/java/security/KeyStore.html#getDefaultType--[Default Java `KeyStore` type]
| The type of trust store.
See https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyStore[KeyStore types].

| [[log4j2.trustStoreKeyManagerFactoryAlgorithm]]`log4j2.trustStore{zwsp}KeyManagerFactoryAlgorithm`

(`LOG4J_TRUST_STORE_{zwsp}KEY_MANAGER_FACTORY_ALGORITHM`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/javax/net/ssl/KeyManagerFactory.html#getDefaultAlgorithm--[Default Java `KeyManagerFactory` algorithm]
| Name of the https://docs.oracle.com/javase/{java-target-version}/docs/api/javax/net/ssl/KeyManagerFactory.html[KeyManagerFactory] implementation to use for the trust store.
See https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyManagerFactory[KeyManagerFactory types].

| [[log4j2.sslVerifyHostName]]`log4j2.sslVerifyHostName`

(`LOG4J_SSL_VERIFY_HOST_NAME`)
| false
| If `true` enables verification of the name of the TLS server.

3+h| TLS client authentication properties

| [[log4j2.keyStoreLocation]]`log4j2.keyStoreLocation`

(`LOG4J_KEY_STORE_LOCATION`)
| see link:{jsse-default-keystores}[Default Java key store]
| The location of the private key store.

| [[log4j2.keyStorePassword]]`log4j2.keyStorePassword`

(`LOG4J_KEY_STORE_PASSWORD`)
|
| The password for the private key store.

| [[log4j2.keyStorePasswordFile]]`log4j2.keyStore{zwsp}PasswordFile`

(`LOG4J_KEY_STORE_{zwsp}PASSWORD_FILE`)
|
| The name of a file that contains the password for the private key store.

| [[log4j2.keyStorePasswordEnvironmentVariable]]`log4j2.keyStore{zwsp}PasswordEnvironmentVariable`

(`LOG4J_KEY_STORE_{zwsp}PASSWORD_ENVIRONMENT_VARIABLE`)
|
| The name of the environment variable that contains the password for the private key store.

| [[log4j2.keyStoreType]]`log4j2.keyStoreType`

(`LOG4J_KEY_STORE_TYPE`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/java/security/KeyStore.html#getDefaultType--[Default Java `KeyStore` type]
| The type of private key store.
See https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyStore[KeyStore types].

| [[log4j2.keyStoreKeyManagerFactoryAlgorithm]]`log4j2.keyStore{zwsp}KeyManagerFactoryAlgorithm`

(`LOG4J_KEY_STORE_{zwsp}KEY_MANAGER_FACTORY_ALGORITHM`)
| https://docs.oracle.com/javase/{java-target-version}/docs/api/javax/net/ssl/KeyManagerFactory.html#getDefaultAlgorithm--[Default Java `KeyManagerFactory` algorithm]
| Name of the https://docs.oracle.com/javase/{java-target-version}/docs/api/javax/net/ssl/KeyManagerFactory.html[KeyManagerFactory] implementation to use for the private key store.
See https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyManagerFactory[KeyManagerFactory types].

|===

=== Miscellaneous properties

.Miscellaneous configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.clock]]`log4j2.clock`

(`LOG4J_CLOCK`)
| `SystemClock`
a|
Specifies the link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/Clock[Clock] implementation used to timestamp log events.

The possible values are:

* `SystemClock`: uses the best available system clock as time source.
See https://docs.oracle.com/javase/{java-target-version}/docs/api/java/time/Clock.html#systemDefaultZone--[Clock#systemDefaultZone] for details.

* `SystemMillisClock`: same as `SystemClock`, but truncates the result to a millisecond.

* `CachedClock`: uses a separate thread to update the timestamp value.
See link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/CachedClock[JavaDoc] for details.

* `CoarseCachedClock`: alternative implementation of `CachedClock` with a slightly lower precision.
See link:..//javadoc/log4j-core/org/apache/logging/log4j/core/util/CoarseCachedClock[JavaDoc] for details.

* the fully qualified name of a custom implementation.

| [[log4j2.contextDataInjector]]`log4j2.contextDataInjector`

(`LOG4J_CONTEXT_DATA_INJECTOR`)
| depends on the `ThreadContextMap` implementation
| Fully specified class name of a link:../javadoc/log4j-core/org/apache/logging/log4j/core/ContextDataInjector[ContextDataInjector] implementation.

The default implementation uses all implementations of link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/ContextDataProvider[ContextDataProvider] registered with `ServiceLoader`.

| [[log4j2.logEventFactory]]`log4j2.logEventFactory`

(`LOG4J_LOG_EVENT_FACTORY`)
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/impl/DefaultLogEventFactory[DefaultLogEventFactory]

(GC-free mode: link:../javadoc/log4j-core/org/apache/logging/log4j/core/impl/ReusableLogEventFactory[ReusableLogEventFactory])
|
Specifies the link:../javadoc/log4j-core/org/apache/logging/log4j/core/impl/LogEventFactory[LogEventFactory]
implementation to use to create log events.

| [[log4j2.shutdownHookEnabled]]`log4j2.shutdownHookEnabled`

(`LOG4J_SHUTDOWN_HOOK_ENABLED`)
| `true`

(Web-app mode: `false`)
|
If `true` a shutdown hook will be installed to stop all logger contexts when the system stops.

| [[log4j2.shutdownCallbackRegistry]]`log4j2.shutdownCallbackRegistry`

(`LOG4J_SHUTDOWN_CALLBACK_REGISTRY`)
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/DefaultShutdownCallbackRegistry[DefaultShutdownCallbackRegistry]
|
The fully qualified class name of a link:../javadoc/log4j-core/org/apache/logging/log4j/core/util/ShutdownCallbackRegistry[ShutdownCallbackRegistry] implementation.
Integrators can use this to customize the shutdown order of the JVM.

The default implementation executes all shutdown actions in a separate `Thread` registered through https://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#addShutdownHook-java.lang.Thread-[Runtime#addShutdownHook()].


| [[log4j2.uuidSequence]]`log4j2.uuidSequence`

(`LOG4J_UUID_SEQUENCE`)
| 0
|
Provides a `long` see to the UUID generator used by the `%uuid` pattern converter.

Can be used to assure uniqueness of UUIDs generated by multiple JVMs on the same machine.

| [[log4j2.messageFactory]]`log4j2.messageFactory`

(`LOG4J_MESSAGE_FACTORY`)
| link:../javadoc/log4j-api/org/apache/logging/log4j/message/ParameterizedMessageFactory[ParameterizeMessageFactory]

(GC-free mode: link:../javadoc/log4j-api/org/apache/logging/log4j/message/ReusableMessageFactory[ReusableMessageFactory])
| Default message factory used by loggers if no factory was specified.

| [[log4j2.flowMessageFactory]]`log4j2.flowMessageFactory`

(`LOG4J_FLOW_MESSAGE_FACTORY`)
| link:../javadoc/log4j-api/org/apache/logging/log4j/message/DefaultFlowMessageFactory[DefaultFlowMessageFactory]
| Default flow message factory used by Loggers.

| [[log4j2.loggerContextStacktraceOnStart]]`log4j2.loggerContext{zwsp}StacktraceOnStart`

(`LOG4J_LOGGER_CONTEXT_{zwsp}STACKTRACE_ON_START`)
| `false`
| Prints a stacktrace to the xref:manual/configuration.adoc#StatusMessages[status logger] at `DEBUG` level when the LoggerContext is started.

For debug purposes only.

| [[log4j2.scriptEnableLanguages]]`log4j2.scriptEnableLanguages`

(`LOG4J_SCRIPT_ENABLE_LANGUAGES`)
|
| The list of script languages that are allowed to execute.

The names specified must correspond to those returned by https://docs.oracle.com/javase/{java-target-version}/docs/api/javax/script/ScriptEngineFactory.html#getNames--[ScriptEngineFactory#getNames()].

|===

== JUL-to-Log4j API bridge

The JUL-to-Log4j API bridge provides the following configuration properties:

.JUL configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.julLevelConverter]]`log4j2.julLevelConverter`

(`LOG4J_JUL_LEVEL_CONVERTER`)
|
|
Fully qualified name of an alternative `org.apache.logging.log4j.jul.LevelConverter` implementation.

See xref:log4j-jul.adoc#default-level-conversions[Default Level Conversions] for the default implementation.

| [[log4j2.julLoggerAdapter]]`log4j2.julLoggerAdapter`

(`LOG4J_JUL_LOGGER_ADAPTER`)
| depends on classpath
a|
This property allows users to choose between two implementation of the logging bridge:

* `org.apache.logging.log4j.jul.CoreLoggerAdapter` (default if `log4j-core` present) allows users to modify the Log4j Core configuration through the JUL https://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html[Logger] interface,

* `org.apache.logging.log4j.jul.ApiLoggerAdapter` (default if `log4j-core` absent) disables the level mutators in the JUL `Logger` interface.

|===

== Log4j Spring Boot

The Log4j Spring Boot module supports the following configuration properties:

.Spring Boot configuration properties
[cols="1,1,5"]
|===
h| Java Property

(Environment Variable)
h| Default Value
h| Description

| [[log4j2.disableCloudConfigLoggingSystem]]`log4j2.disable{zwsp}CloudConfigLoggingSystem`

(`LOG4J_DISABLE_{zwsp}CLOUD_CONFIG_LOGGING_SYSTEM`)
| `false`
| Disables the usage of the Spring Boot `Log4j2CloudConfigLoggingSystem`.

|===

[#property-sources]
== Property sources

The Log4j configuration properties sub-system merges the content of multiple property sources that implement the Java interface link:../javadoc/log4j-api/org/apache/logging/log4j/util/PropertySource[PropertySource].

Additional property source classes can be added through:

* the standard Java SE https://docs.oracle.com/en/java/javase/{java-target-version}/docs/api/java.base/java/util/ServiceLoader.html[ServiceLoader] mechanism,
* programmatically using `PropertiesUtil#addPropertySource` and `PropertiesUtil#removePropertySource`.

Each property source can define its own naming convention for property names, although most of them support the standard:

----
log4j2.camelCasePropertyName
----

convention.

Properties can be overridden by sources with a lower numerical priority (e.g. -100 comes before 100).

Log4j provides the following implementations:

.PropertySource priorities and descriptions
[cols="2m,1m,1,1m,5"]
|===
| Name | Priority | Naming Convention | Module | Description

| SpringPropertySource
| -100
| standard
| log4j-spring
| Delegates property resolution to a Spring https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/core/env/Environment.html[Environment]. See xref:log4j-spring-boot.adoc[] for details.

| SystemPropertiesPropertySource
| 0
| standard
| log4j-api
| Resolves properties using Java https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html[System Properties].

| EnvironmentPropertySource
| 100
| **custom**
| log4j-api
a| Resolves properties using environment variables.

**Warning**: The naming convention of this property source differs from the standard one.
The property name is prefixed with LOG4J_, is in all caps and words are all separated by underscores.

| PropertyFilePropertySource
| 200
| standard
| log4j-api
| Resolves properties using all the resources named `log4j2.component.properties` found on the classpath.
This property source should be used to change the default values of an application.
|===