Target Pattern

A target pattern is a string that resolves to a set of targets. A target pattern can be used as arguments to commands, such as buck2 build and buck uquery. You can also use build target patterns in the visibility argument of your build rules.

The simplest build target pattern matches the build target of the same name:

#
# Matches //apps/myapp:app
#
//apps/myapp:app

A build target pattern that ends with a colon matches all build targets in the build file at the preceding directory path. For example, suppose that the build file:

apps/myapp/BUCK

defines the rules: app_v1 and app_v2, then the following build target pattern would match both of those rules:

#
# Matches //apps/myapp:app_v1 and //apps/myapp:app_v2
#
//apps/myapp:

A build target pattern that ends with an ellipsis (/...) matches all build targets in the build file in the directory that precedes the ellipsis and also all build targets in build files in subdirectories. For example, suppose that you have the following build files:

apps/BUCK
apps/myapp/BUCK

then the following pattern would match all build targets in both of those files:

#
# Matches (for example) //apps:common and //apps/myapp:app
#
//apps/...

A target pattern that does not include a : separator matches the target with the same name as the last element of the path:

#
# Matches //apps/myapp:myapp
#
//apps/myapp

Finally, target patterns can be relative to your current directory. For example:

#
# If your current working directory is `apps`, matches //apps/myapp:myapp
#
myapp:myapp

Build target patterns are not allowed in the deps argument

Build target patterns cannot be used with the deps argument of a build rule. Buck requires that you specify all dependencies explicitly as either fully-qualified or relative build targets.

Target aliases

Buck supports the ability to define aliases for build targets; using aliases can improve brevity when specifying targets on the Buck command line.

To see which aliases exist, use buck2 audit config alias.