BUILDING.adoc

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[#requirements]
== Requirements

* JDK 17+
* A modern Linux, OSX, or Windows host

[#building]
== Building the sources

You can build and verify the sources as follows:

[source,bash]
----
./mvnw verify
----

`verify` goal runs validation and test steps next to building (i.e., compiling) the sources.
To speed up the build, you can skip verification:

[source,bash]
----
./mvnw -DskipTests package
----

If you want to install generated artifacts to your local Maven repository, replace above `verify` and/or `package` goals with `install`.

[#dns]
=== DNS lookups in tests

Note that if your `/etc/hosts` file does not include an entry for your computer's hostname, then many unit tests may execute slow due to DNS lookups to translate your hostname to an IP address in `InetAddress.getLocalHost()`.
To remedy this, you can execute the following:

[source,bash]
----
printf '127.0.0.1 %s\n::1 %s\n' `hostname` `hostname` | sudo tee -a /etc/hosts
----

[#java8-tests]
=== Java 8 tests

You can run tests using the target JRE (i.e., JRE 8) as follows:

[#toolchains]
. Maven Toolchains is used to employ additional JDKs required for tests.
You either need to have a user-level configuration in `~/.m2/toolchains.xml` or explicitly provide one to the Maven: `./mvnw --global-toolchains /path/to/toolchains.xml`.
+
.An example `toolchains.xml` containing a JDK 8 toolchain
[source,xml]
----
<?xml version="1.0" encoding="UTF8"?>
<toolchains>
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>1.8.0_372</version>
    </provides>
    <configuration>
      <jdkHome>/usr/lib/jvm/java-8-openjdk-amd64</jdkHome>
    </configuration>
  </toolchain>
</toolchains>
----

. Run Maven tests with the `java8-tests` profile:
+
[source,bash]
----
./mvnw verify -Pjava8-tests,!java8-incompat-fixes
----

[#website]
== Building the website

You can build the website as follows:

[source,bash]
----
./mvnw compile    # <1>
./mvnw site       # <2>
----
<1> Generate plugin descriptors that will be used to generate the plugin reference page.
Descriptors are placed under `target/plugin-descriptors`.
<2> Generate the website to `target/site`

You can view the generated website with a browser by pointing it to `target/site` directory.

[#development]
== Development

You can follow below steps for casual development needs:

. Make sure you installed everything:
+
[source,bash]
----
./mvnw install -DskipTests
----

. After making a change to, say, `log4j-core`, install your changes:
+
[source,bash]
----
./mvnw install -pl :log4j-core -DskipTests
----

. Run all tests associated with `log4j-core`:
+
[source,bash]
----
./mvnw test -pl :log4j-core-test
----

. Run a particular test:
+
[source,bash]
----
./mvnw test -pl :log4j-core-test -Dtest=FooBarTest
----

. Make sure all build checks (Spotless, Spotbugs, BND, RAT, etc.) succeed:
+
[source,bash]
----
./mvnw verify -DskipTests -pl :log4j-core,:log4j-core-test
----

[TIP]
====
You can connect your IDE to a `./mvnw test` run by

. Run `./mvnw test -pl :log4j-core-test -Dtest=FooBarTest -Dmaven.surefire.debug`
. Use _"Run > Attach to process"_ in IntelliJ IDEA
====

[#development-faq]
=== F.A.Q

[#development-faq-idea-plugin-not-found]
==== Compilation in IntelliJ IDEA fails with `java: plug-in not found: ErrorProne`

Try removing all _"Override compiler parameters per-module"_ entries in _"Settings > Build, Execution, Deployment > Compiler > Java Compiler"_.