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A fast build system that encourages the creation of small, reusable modules over a variety of platforms and languages.
Updated 1 month ago

Use Buck2

This repo is dead.

Please see for the build system that replaces it.

Old content continues below for historical purposes.





Buck is a build tool. To see what Buck can do for you, check out the documentation at

Build Status


Since Buck is used to build Buck, the initial build process involves 2 phases:

1. Clone the Buck repository and bootstrap it with ant:
git clone --depth 1
cd buck

You must be using Java 8 or 11 for this to compile successfully. If you see compilation errors from ant, check your JAVA_HOME is pointing at one of these versions.

2. Use bootstrapped version of Buck to build Buck:
./bin/buck build --show-output buck
# output will contain something like
# //programs:buck buck-out/gen/programs/buck.pex
buck-out/gen/programs/buck.pex --help
Prebuilt buck binaries

Pre-built binaries of buck for any buck sha can be downloaded from<sha>/buck-<sha>.pex. The very first time a version of buck is requested, it is built via jitpack. As a result, it could take a few minutes for this initial binary to become available. Every subsequent request will just serve the built artifact directly. This functionality is available for any fork of buck as well, so you can fetch<github-user-or-org>/buck/<sha>/buck-<sha>.pex

For buck binaries built for JDK 11, modify end of the url to buck-<sha>-java11.pex.

Feature Deprecation

Buck tries to move fast with respect to its internals. However, for user facing features (build rules, command line interface, etc), the Buck team tries to have a graceful deprecation process. Note that this generally applies only to documented functionality, or functionality that is less documented, but appears to be in wide use. That process is:

  • An issue is opened on Github suggesting what will be deprecated, and when it will be removed. For larger features that are deprecated, there may be a period when the default is the new setting, and the old behavior may only be used with a configuration change.
  • A change is submitted to Buck that puts the old behavior behind a configuration flag and sets the default to the old behavior. These flags can be found at
  • For larger features, a change eventually is put in place that sets the default to the new behavior. e.g. when Skylark becomes the default build file parser.
  • When the removal date is reached, a change is submitted to remove the feature. At this point, the configuration value will still parse, but will not be used by Buck internally.


Apache License 2.0