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 6.0.0 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", version = "r25c")

You can also customize the base_url attribute if, for example, you mirror the NDK archives on a private server.

Some sha256 checksums are included in this repository, but these might not be up to date, if you want to use a version of the NDK that's not included, you can also specify the sha256sums attribute which maps platforms to checksums, like so:

android_ndk_repository(
    name = "androidndk",
    version = "r25c"
    sha256sums = {
        "windows": "f70093964f6cbbe19268f9876a20f92d3a593db3ad2037baadd25fd8d71e84e2",
        "darwin": "b01bae969a5d0bfa0da18469f650a1628dc388672f30e0ba231da5c74245bc92",
        "linux": "769ee342ea75f80619d985c2da990c48b3d8eaf45f48783a2d48870d04b46108",
    }
)

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.