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# Building Log4j 2
To build Log4j 2, you need a JDK implementation version 1.7 or greater, JDK
version 9, and Apache Maven 3.x.
Log4j 2.x uses the Java 9 compiler in addition to
the Java version installed in the path. This is accomplished by using Maven's toolchains support.
Log4j 2 provides sample toolchains XML files in the root folder. This may be used by
modifying it and installing the file as toolchains.xml in the .m2 folder or by using the
following when invoking Maven.
```
[Macintosh] -t ./toolchains-sample-mac.xml
[Windows] -t ./toolchains-sample-win.xml
[Linux] -t ./toolchains-sample-linux.xml
```
To perform the license release audit, a.k.a. "RAT check", run.
mvn apache-rat:check
To build the site with Java 7, make sure you give Maven enough memory using
`MAVEN_OPTS` with options appropriate for your JVM. Alternatively, you can
build with Java 8 and not deal with `MAVEN_OPTS`.
To install the jars in your local Maven repository, from a command line, run:
mvn clean install
Once install is run, you can run the Clirr check on the API and 1.2 API modules:
mvn clirr:check -pl log4j-api
mvn clirr:check -pl log4j-1.2-api
Next, to build the site:
If Java 7 runs out of memory building the site, you will need:
set MAVEN_OPTS=-Xmx2000m -XX:MaxPermSize=384m
mvn site
On Windows, use a local staging directory, for example:
mvn site:stage-deploy -DstagingSiteURL=file:///%HOMEDRIVE%%HOMEPATH%/log4j
On UNIX, use a local staging directory, for example:
mvn site:stage-deploy -DstagingSiteURL=file:///$HOME/log4j
To test, run:
mvn clean install
## Testing in Docker
In order to run a clean test using the minimum version of the JDK along with a
proper Linux environment, run:
docker build .