CODEWITHSUNDEEP
androidandroid-ndkbazel
Rickard F.
Rickard F.

Reputation: 11

Pack additional native libs into the APK with bazel

I'm using the bazel functions android_library() and android_binary() to build an APK. My android_library has a dependency to a native lib built with cc_library(). The native lib gets packed into the APK but I would like to pack an additional native lib into the APK.

I have tried to add the additional lib as a dependency to android_library() to no avail. It gets built but does not get packed into the APK.

In the build.gradle that I used before I started migrating to bazel this was achieved by using the "sourceSets" section:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28

    defaultConfig {
        applicationId = 'com.my.runtime'
        minSdkVersion 14
        targetSdkVersion 26
        versionCode = 1
        versionName = '1.0'
        externalNativeBuild {
            cmake {
                arguments '-DANDROID_STL=c++_static'
            }
        }
    }
     splits {
        abi {
            reset()
            enable true
            universalApk false  // If true, also generate a universal APK
            include "arm64-v8a"
        }
    }
    buildTypes {
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'),
                          'proguard-rules.pro'
        }
    }
    sourceSets {
        main {
            // let gradle pack the additional shared library into apk
            jniLibs.srcDirs = ['../additional_lib']
        }
    }
    externalNativeBuild {
        cmake {
            version '3.15.5'
            path 'src/main/jni/CMakeLists.txt'
        }
    }
}

dependencies {
    implementation 'com.android.support:appcompat-v7:26.0.0'
}

How could I achieve this by using the bazel functions?

Upvotes: 1

Views: 557

Answers (1)

ahumesky
ahumesky

Reputation: 5016

The way to do this is with a cc_import: https://docs.bazel.build/versions/master/be/c-cpp.html#cc_import

Then have your android_binary depend on that cc_import.

If you have a .so for each architecture you want to support, then you can import them all using cc_import, select(), and config_setting. For example, if you have a directory called libs with this structure:

$ tree libs
libs
├── arm64-v8a
│   └── libsomething.so
├── armeabi-v7a
│   └── libsomething.so
├── x86
│   └── libsomething.so
└── x86_64
    └── libsomething.so

Then you can create a BUILD file in libs like this:


config_setting(
  name = "x86",
  values = {
    "cpu": "x86",
  }
)

config_setting(
  name = "x86_64",
  values = {
    "cpu": "x86_64",
  }
)

config_setting(
  name = "armeabi-v7a",
  values = {
    "cpu": "armeabi-v7a",
  }
)

config_setting(
  name = "arm64-v8a",
  values = {
    "cpu": "arm64-v8a",
  }
)

cc_import(
  name = "lib",
  shared_library = select({
    ":x86": "x86/libsomething.so",
    ":x86_64": "x86_64/libsomething.so",
    ":armeabi-v7a": "armeabi-v7a/libsomething.so",
    ":arm64-v8a": "arm64-v8a/libsomething.so",
  }),
  visibility = ["//visibility:public"],
)

Then have your android_binary depend on lib. Then when you build with --fat_apk_cpu, each .so will be packaged for its respective architecture, e.g.:

bazel build java/com/app --fat_apk_cpu=x86,x86_64,armeabi-v7a,arm64-v8a

$ unzip -l bazel-bin/java/com/app/app.apk
Archive:  bazel-bin/java/com/app/app.apk
  Length      Date    Time    Name
---------  ---------- -----   ----
        9  2010-01-01 00:00   nativedeps
   274288  2010-01-01 00:00   lib/arm64-v8a/libapp.so
 18770760  2010-01-01 00:00   lib/arm64-v8a/libsomething.so
   189796  2010-01-01 00:00   lib/armeabi-v7a/libapp.so
 10076740  2010-01-01 00:00   lib/armeabi-v7a/libsomething.so
   239312  2010-01-01 00:00   lib/x86/libapp.so
 38612828  2010-01-01 00:00   lib/x86/libsomething.so
   247784  2010-01-01 00:00   lib/x86_64/libapp.so
 53690632  2010-01-01 00:00   lib/x86_64/libsomething.so
     2760  2010-01-01 00:00   classes.dex
     1832  2010-01-01 00:00   AndroidManifest.xml
      728  2010-01-01 00:00   res/layout/main_layout.xml
      768  2010-01-01 00:00   resources.arsc
     1374  2010-01-01 00:00   META-INF/CERT.SF
     1211  2010-01-01 00:00   META-INF/CERT.RSA
     1270  2010-01-01 00:00   META-INF/MANIFEST.MF
---------                     -------
122112092                     16 files

Upvotes: 2

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