There is currently no binary distribution of Buck, so it has to be manually built and installed. Apache Ant is required. Currently only Linux and Mac OS are supported.

Clone the git and build it:

  git clone
  cd buck

Make sure you have a bin/ directory in your home directory and that it is included in your path:

  mkdir ~/bin

Add a symbolic link in ~/bin to the buck executable:

  ln -s `pwd`/bin/buck ~/bin/

Verify that buck is accessible:

  which buck

If you plan to use the Buck daemon add a symbolic link in ~/bin to the buckd executable:

  ln -s `pwd`/bin/buckd ~/bin/

To enable autocompletion of buck commands, install the autocompletion script from ./scripts/bash_completion in the buck project. Refer to the script’s header comments for installation instructions.

Eclipse Integration

Generating the Eclipse Project

Create the Eclipse project:


In Eclipse, choose Import existing project and select the gerrit project from the current working directory.

Expand the gerrit project, right-click on the buck-out folder, select Properties, and then under Attributes check Derived.

Note that if you make any changes in the project configuration that get saved to the .project file, for example adding Resource Filters on a folder, they will be overwritten the next time you run tools/eclipse/

Refreshing the Classpath

If an updated classpath is needed, the Eclipse project can be refreshed and missing dependency JARs can be downloaded:


Attaching Sources

To save time and bandwidth source JARs are only downloaded by the buck build where necessary to compile Java source into JavaScript using the GWT compiler. Additional sources may be obtained, allowing Eclipse to show documentation or dive into the implementation of a library JAR:

  tools/eclipse/ --src

Building on the Command Line

Gerrit Development WAR File

To build the Gerrit web application:

  buck build gerrit

The output executable WAR will be placed in:


Extension and Plugin API JAR Files

To build the extension and plugin API JAR files:

  buck build api

The output JAR files will be placed in:


Install {extension,plugin}-api to the local maven repository:

  buck build api_install

Deploy {extension,plugin}-api to the remote maven repository

  buck build api_deploy

The type of the repo is induced from the Gerrit version name, i.e. * 2.8-SNAPSHOT: snapshot repo * 2.8: release repo


To build all core plugins:

  buck build plugins:core

The output JAR files for individual plugins will be placed in:


The JAR files will also be packaged in:


To build a specific plugin:

  buck build plugins/<name>

The output JAR file will be be placed in:


Note that when building an individual plugin, the package is not regenerated.


To build the documentation:

  buck build docs

The generated html files will be placed in:


The html files will also be bundled into in this location:


Gerrit Release WAR File

To build the release of the Gerrit web application, including documentation and all core plugins:

  buck build release

The output release WAR will be placed in:


Running Unit Tests

To run all tests including acceptance tests:

  buck test --all

To exclude slow tests:

  buck test --all --exclude slow

To run a specific test, e.g. the acceptance test

  buck test //gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git:HttpPushForReviewIT


Dependency JARs are normally downloaded automatically, but Buck can inspect its graph and download any missing JAR files. This is useful to enable subsequent builds to run without network access:


When downloading from behind a proxy (which is common in some corporate environments), it might be necessary to explicitly specify the proxy that is then used by curl:

  export http_proxy=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>

Redirection to local mirrors of Maven Central and the Gerrit storage bucket is supported by defining specific properties in, a file that is not tracked by Git:

  echo download.GERRIT = >>
  echo download.MAVEN_CENTRAL = >>

The file may be placed in the root of the gerrit repository being built, or in ~/.gerritcodereview/. The file in the root of the gerrit repository has precedence.

Building against unpublished Maven JARs

To build against unpublished Maven JARs, like gwtorm or PrologCafe, the custom JARs must be installed in the local Maven repository (mvn clean install) and maven_jar() must be updated to point to the MAVEN_LOCAL Maven repository for that artifact:

   name = 'gwtorm',
   id = 'gwtorm:gwtorm:42',
   license = 'Apache2.0',
   repository = MAVEN_LOCAL,

Caching Build Results

Build results can be locally cached, saving rebuild time when switching between Git branches. Buck’s documentation covers caching in buckconfig. The trivial case using a local directory is:

  cat >.buckconfig.local <<EOF
    mode = dir
    dir = buck-cache

Using Buck daemon

Buck ships with a daemon command buckd, which uses the Nailgun protocol for running Java programs from the command line without incurring the JVM startup overhead.

Using a Buck daemon can save significant amounts of time as it avoids the overhead of starting a Java virtual machine, loading the buck class files and parsing the build files for each command.

It is safe to run several buck daemons started from different project directories and they will not interfere with each other. Buck’s documentation covers daemon in buckd.

The trivial use case is to run buckd from the project’s root directory and run buck as usual:

  buck build gerrit
  Using buckd.

Override Buck’s settings

User-specific configuration can be placed in one of the following files: /etc/buck.conf, $HOME/.buck/buck.conf or $HOME/.buckrc.

For example to override Buck’s default 1GB heap size:

  cat > $HOME/.buckrc <<EOF
  -XX:MaxPermSize=512m \
  -Xms8000m \

Or to debug BUCK, set BUCK_DEBUG_MODE to anything non-empty, then connect to port 8888:

  cat > $HOME/.buckrc <<EOF
  export BUCK_DEBUG_MODE="yes"