Language Support

Bazelle provides support for multiple programming languages through Gazelle extensions. Each language extension must be explicitly enabled (except Go and Proto which are enabled by default).

Registered Languages

Go

Built-in Gazelle support for go_library, go_binary, and go_test rules. Enabled by default. Learn more →

Kotlin

Custom extension for kt_jvm_library and kt_jvm_test. Requires Maven-style layout. Learn more →

Python

Custom extension for py_library, py_binary, and py_test. Detects if __name__ == "__main__": blocks. Learn more →

C/C++

Via gazelle_cc for cc_library, cc_binary, and cc_test. Learn more →

Status Overview

Language	Registered	Default	Rules Generated
Go	✅ Yes	Enabled	go_library, go_binary, go_test
Proto	✅ Yes	Enabled	proto_library, go_proto_library
Kotlin	✅ Yes	Disabled	kt_jvm_library, kt_jvm_test
Python	✅ Yes	Disabled	py_library, py_binary, py_test
C/C++	✅ Yes	Disabled	cc_library, cc_binary, cc_test
Groovy	✅ Yes	Disabled	groovy_library, groovy_test
Java	❌ No	—	Blocked on Bazel 9 compatibility
Scala	❌ No	—	Planned
Rust	❌ No	—	Blocked on proto dependencies

Note

Only Go and Proto are enabled by default. Other languages must be explicitly enabled via directives like # gazelle:kotlin_enabled true.

How It Works

Bazelle runs all enabled language extensions on your codebase. Each extension:

1. Scans source files to detect language-specific patterns
2. Parses files to extract imports and dependencies
3. Generates appropriate BUILD rules with correct deps and srcs

Language Detection

When you run bazelle init, it detects languages by scanning for file extensions:

Extensions	Language
.go	Go
.kt, .kts	Kotlin
.java	Java
.py	Python
.proto	Proto
.groovy	Groovy
.cc, .cpp, .cxx, .c, .h, .hpp, .hxx	C/C++

Ignored directories: bazel-*, .*, node_modules, __pycache__, vendor

Enabling Languages

Enable languages via BUILD file directives:

# In your root BUILD.bazel

# Enable Kotlin
# gazelle:kotlin_enabled true

# Enable Python
# gazelle:python_enabled true

# Enable Groovy
# gazelle:groovy_enabled true

Or filter at runtime:

# Only run Go and Kotlin extensions
bazelle update --languages go,kotlin