subparticles/onnxruntime-build repository overview

⁠Onnxruntime-build

This project contains a Dockerfile to build the onnxruntime Android library. It is based on this image that contains all the prerequisites https://github.com/subparticles/onnxruntime-ci⁠.

The build can take several minutes (30-90 minutes) to complete and the size of the produced image is almost 20 GB.

Example of build command:

docker build . -t onnxruntime_build:1.7.2-android-arm64

Create a container to extract the aar

id=$(docker create onnxruntime_build:1.7.2-android-arm64)
docker cp $id:/home/user/code/onnxruntime/build/Android/Debug/java/build/android/outputs/aar .

⁠Reference

See below a copy of the Android build procedure taken from https://www.onnxruntime.ai/docs/how-to/build.html#android⁠

⁠Android

⁠Prerequisites

The SDK and NDK packages can be installed via Android Studio or the sdkmanager command line tool. Android Studio is more convenient but a larger installation. The command line tools are smaller and usage can be scripted, but are a little more complicated to setup. They also require a Java runtime environment to be available.

Resources:

• API levels: https://developer.android.com/guide/topics/manifest/uses-sdk-element.html⁠
• Android ABIs: https://developer.android.com/ndk/guides/abis⁠
• System Images: https://developer.android.com/topic/generic-system-image⁠

⁠Android Studio

1. Install Android Studio from https://developer.android.com/studio⁠
2. Install any additional SDK Platforms if necessary

• File->Settings->Appearance & Behavior->System Settings->Android SDK to see what is currently installed
• Note that the SDK path you need to use as –android_sdk_path when building ORT is also on this configuration page
• Most likely you don’t require additional SDK Platform packages as the latest platform can target earlier API levels.

1. Install an NDK version

• File->Settings->Appearance & Behavior->System Settings->Android SDK
• ‘SDK Tools’ tab
  • Select ‘Show package details’ checkbox at the bottom to see specific versions. By default the latest will be installed which should be fine.
• The NDK path will be the ‘ndk/{version}’ subdirectory of the SDK path shown
  • e.g. if 21.1.6352462 is installed it will be {SDK path}/ndk/21.1.6352462

⁠sdkmanager from command line tools

• If necessary install the Java Runtime Environment and set the JAVA_HOME environment variable to point to it

  • https://www.java.com/en/download/⁠
  • Windows note: You MUST install the 64-bit version (https://www.java.com/en/download/manual.jsp⁠) otherwise sdkmanager will only list x86 packages and the latest NDK is x64 only.

• For sdkmanager to work it needs a certain directory structure. First create the top level directory for the Android infrastructure.

  • in our example we’ll call that .../Android/

• Download the command line tools from the ‘Command line tools only’ section towards the bottom of https://developer.android.com/studio⁠

• Create a directory called ‘cmdline-tools’ under your top level directory

  • giving .../Android/cmdline-tools

• Extract the ‘tools’ directory from the command line tools zip file into this directory

  • giving .../Android/cmdline-tools/tools

  • Windows note: preferably extract using 7-zip. If using the built in Windows zip extract tool you will need to fix the directory structure by moving the jar files from

    tools\lib\_
    

    Copy

    up to

    tools\lib
    

    Copy
    • See https://stackoverflow.com/questions/27364963/could-not-find-or-load-main-class-com-android-sdkmanager-main⁠

• You should now be able to run Android/cmdline-tools/bin/sdkmanager[.bat] successfully

  • if you see an error about it being unable to save settings and the sdkmanager help text, your directory structure is incorrect.
  • see the final steps in this answer to double check: https://stackoverflow.com/a/61176718⁠

• Run .../Android/cmdline-tools/bin/sdkmanager --list to see the packages available

• Install the SDK Platform

  • Generally installing the latest is fine. You pick an API level when compiling the code and the latest platform will support many recent API levels e.g.

    sdkmanager --install "platforms;android-29"
    

    Copy

  • This will install into the ‘platforms’ directory of our top level directory, the Android directory in our example

  • The SDK path to use as --android_sdk_path when building is this top level directory

• Install the NDK

  • Find the available NDK versions by running sdkmanager --list
  • Install
    • you can install a specific version or the latest (called ‘ndk-bundle’) e.g. sdkmanager --install "ndk;21.1.6352462"
    • NDK path in our example with this install would be .../Android/ndk/21.1.6352462
    • NOTE: If you install the ndk-bundle package the path will be .../Android/ndk-bundle as there’s no version number

⁠Android Build Instructions

⁠Cross compiling on Windows

The Ninja⁠ generator needs to be used to build on Windows as the Visual Studio generator doesn’t support Android.

./build.bat --android --android_sdk_path <android sdk path> --android_ndk_path <android ndk path> --android_abi <android abi, e.g., arm64-v8a (default) or armeabi-v7a> --android_api <android api level, e.g., 27 (default)> --cmake_generator Ninja

e.g. using the paths from our example

./build.bat --android --android_sdk_path .../Android --android_ndk_path .../Android/ndk/21.1.6352462 --android_abi arm64-v8a --android_api 27 --cmake_generator Ninja

⁠Cross compiling on Linux and macOS

./build.sh --android --android_sdk_path <android sdk path> --android_ndk_path <android ndk path> --android_abi <android abi, e.g., arm64-v8a (default) or armeabi-v7a> --android_api <android api level, e.g., 27 (default)>

⁠Build Android Archive (AAR)

Android Archive (AAR) files, which can be imported directly in Android Studio, will be generated in your_build_dir/java/build/outputs/aar, by using the above building commands with --build_java

To build on Windows with --build_java enabled you must also:

• set JAVA_HOME to the path to your JDK install

  • this could be the JDK from Android Studio, or a standalone JDK install⁠
  • e.g. Powershell: $env:JAVA_HOME="C:\Program Files\Java\jdk-15" CMD: set JAVA_HOME=C:\Program Files\Java\jdk-15

• install

  Gradle

  and add the directory to the PATH

  • e.g. Powershell: $env:PATH="$env:PATH;C:\Gradle\gradle-6.6.1\bin" CMD: set PATH=%PATH%;C:\Gradle\gradle-6.6.1\bin

• run the build from an admin window

  • the Java build needs permissions to create a symlink, which requires an admin window

⁠Android NNAPI Execution Provider

If you want to use NNAPI Execution Provider on Android, see NNAPI Execution Provider⁠.

⁠Build Instructions

Android NNAPI Execution Provider can be built using building commands in Android Build instructions⁠ with --use_nnapi