Buildozer Module

Transformations for creating, modifying, and deleting Bazel BUILD targets using Buildozer.

buildozer.modify

Runs Buildozer commands against one or more targets.

buildozer.modify(
    target = "foo/bar:lib",
    commands = [
        buildozer.cmd("add deps :utils"),
        buildozer.cmd("set visibility //..."),
    ],
)

Parameters

Parameter	Type	Description
target	string or list[string]	Target expression(s) to modify
commands	list[string|cmd]	Commands to apply

Target Expressions

# Single target
target = "foo/bar:baz"

# All targets in a package
target = "foo/bar:all"

# Multiple targets
target = ["foo/bar:lib", "foo/bar:test"]

# Root BUILD file
target = ".:main"

Example: Add Dependency

buildozer.modify(
    target = "foo/bar:baz",
    commands = [
        buildozer.cmd("set config \":foo\""),
    ],
)

Example: Multiple Targets

buildozer.modify(
    target = ["foo/bar:baz", "foo/bar:fooz"],
    commands = [
        buildozer.cmd("set config \":foo\""),
    ],
)

buildozer.create

Creates a new BUILD target.

buildozer.create(
    target = "pkg:new_lib",
    rule_type = "java_library",
    commands = [
        "set srcs [\"Foo.java\", \"Bar.java\"]",
        "add deps :utils",
    ],
)

Parameters

Parameter	Type	Description
target	string	Target to create (e.g., foo:bar)
rule_type	string	Rule type (e.g., java_library)
commands	list	Commands to populate attributes
before	string	Create before this target
after	string	Create after this target

Positioning

Control where the new target appears:

buildozer.create(
    target = "pkg:new_test",
    rule_type = "java_test",
    after = "pkg:lib",  # Place after existing lib target
    commands = ["set srcs [\"Test.java\"]"],
)

This transformation reverses to delete the target.

buildozer.delete

Deletes a BUILD target.

buildozer.delete(target = "pkg:old_lib")

Parameters

Parameter	Type	Description
target	string	Target to delete
rule_type	string	Rule type (makes deletion reversible)
recreate_commands	list	Commands to recreate (for reversal)
before	string	Position hint for reversal
after	string	Position hint for reversal

Reversible Delete

Provide rule_type to make the deletion reversible:

buildozer.delete(
    target = "pkg:deprecated_lib",
    rule_type = "java_library",
    recreate_commands = [
        "set srcs [\"Old.java\"]",
        "add deps :legacy",
    ],
)

buildozer.cmd

Creates a Buildozer command, optionally with a custom reversal.

buildozer.cmd(
    forward = "add deps :new_dep",
    reverse = "remove deps :new_dep",
)

Parameters

Parameter	Type	Description
forward	string	The command to run
reverse	string	Optional reverse command

Auto-Reversible Commands

These commands reverse automatically:

• add ↔ remove
• remove (element from list) ↔ add
• replace ↔ replace (swapped args)

# No reverse needed - auto-reverses
buildozer.cmd("add deps :foo")

# Custom reverse for non-reversible commands
buildozer.cmd(
    forward = "set visibility //...",
    reverse = "set visibility //pkg:__subpackages__",
)

buildozer.print

Reads an attribute value from a target. Use in custom transformations.

def _check_deps(ctx):
    deps = buildozer.print(
        ctx = ctx,
        attr = "deps",
        target = "pkg:lib",
    )
    if ":banned_dep" in deps:
        ctx.console.error("Found banned dependency!")

Parameters

Parameter	Type	Description
ctx	TransformWork	The transformation context
attr	string	Attribute to read
target	string	Target to read from

buildozer.batch

Combines multiple Buildozer transformations into a single batch for efficiency.

buildozer.batch(
    transforms = [
        buildozer.modify(target = "a:lib", commands = ["add deps :x"]),
        buildozer.modify(target = "b:lib", commands = ["add deps :y"]),
        buildozer.create(target = "c:new", rule_type = "cc_library"),
    ],
)

Common Commands

Buildozer supports many commands. Here are the most useful:

Command	Example	Description
add	add deps :foo	Add to list attribute
remove	remove deps :bar	Remove from list
set	set visibility ["//..."]	Set attribute value
rename	rename old_attr new_attr	Rename attribute
delete	delete testonly	Remove attribute
replace	replace deps :old :new	Replace in list
move	move srcs hdrs *.h	Move between lists

See the Buildozer documentation for the complete command reference.

Use Cases

Migrating Dependencies

Update imports when moving code between repositories:

transformations = [
    buildozer.modify(
        target = "//...:all",
        commands = [
            buildozer.cmd("replace deps @old_repo//lib @new_repo//lib"),
        ],
    ),
]

Standardizing Build Rules

Enforce consistent settings across targets:

buildozer.modify(
    target = ["//src/...:all"],
    commands = [
        "set testonly False",
        "add tags [\"team:platform\"]",
    ],
)