Android NDK Bazel Rules

Overview

This repository contains Starlark rules for integrating Bazel with the Android NDK. These rules currently work with Android NDK version 25b.

NOTE: This is a development preview of the Starlark Android NDK Bazel rules. These rules are not guaranteed to be complete or work for every NDK use case. Bazel versions up to and including 7.0.0 contain a built-in ("native") version of android_ndk_repository described at https://bazel.build/reference/be/android#android_ndk_repository. Over time, these Starlark rules will replace the native version of android_ndk_repository.

Getting Started

To use the Android NDK rules, add the following to your WORKSPACE file:

# Or a later commit
RULES_ANDROID_NDK_COMMIT= "81ec8b79dc50ee97e336a25724fdbb28e33b8d41"
RULES_ANDROID_NDK_SHA = "b29409496439cdcdb50a8e161c4953ca78a548e16d3ee729a1b5cd719ffdacbf"

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
    name = "rules_android_ndk",
    url = "https://github.com/bazelbuild/rules_android_ndk/archive/%s.zip" % RULES_ANDROID_NDK_COMMIT,
    sha256 = RULES_ANDROID_NDK_SHA,
    strip_prefix = "rules_android_ndk-%s" % RULES_ANDROID_NDK_COMMIT,
)
load("@rules_android_ndk//:rules.bzl", "android_ndk_repository")

android_ndk_repository(name = "androidndk")

register_toolchains("@androidndk//:all")

Then, set the ANDROID_NDK_HOME environment variable or the path attribute of android_ndk_repository to the path of the local Android NDK installation directory.

The api_level attribute can also be used to set the Android API level to build against.

Finally, when building an Android app with native dependencies (e.g. cc_library targets), add

--fat_apk_cpu=<cpus> --android_crosstool_top=@androidndk//:toolchain

to your Bazel invocation. <cpus> is a comma-separated list of the available CPUs:

armeabi-v7a
arm64-v8a
x86
x86_64

e.g. --fat_apk_cpu=arm64-v7a or --fat_apk_cpu=arm64-v7a,x86.

These flags may also be added to the your project's .bazelrc file so that they don't have to be specified on the command line.

See the example in https://github.com/bazelbuild/rules_android_ndk/tree/main/examples/basic.

Ticketmaster Extensions

It is possible to download the ndk hermetically using a module extension. The ndk must be downloaded according to the current licenses and it is not provided by this repo.

bazel_dep(name = "rules_android_ndk", version = "0.1.0")

git_override(
    module_name = "rules_android_ndk",
    commit = "<commit>",
    remote = "https://github.com/ticketmaster/rules_android_ndk",
)

ndk = use_extension("@rules_android_ndk//:extensions.bzl", "ndk")

NDK_URL = "https://mycache.example.com/androidndk/%s.tar.gz"

ndk.toolchain(
    api_level = 21,
    sha256 = {
        "darwin_arm64": "<hash>",
        "linux_aarch64": "<hash>",
        "linux_x86_64": "<hash>",
    },
    urls = {
        "darwin_arm64": [NDK_URL % "darwin_arm64"],
        "linux_aarch64": [NDK_URL % "linux_aarch64"],
        "linux_x86_64": [NDK_URL % "linux_x86_64"],
    },
)
use_repo(ndk, "androidndk", "androidndk_darwin_arm64", "androidndk_linux_aarch64", "androidndk_linux_x86_64")

register_toolchains("@androidndk//:all")