Running Python/Pyjnius in Docker container on Android

[bobmorane83]

Hi all,

I'am trying to run python script on Android but in Docker container.
So far, I've Docker running OK on my Android 12 board (aarch64).
Running python is ok in container, but I want to access Android framework now.

I've created a container based on openjdk:11, adding Python 3.9, recompiling pyjnius and having this simple code in it:

from jnius import autoclass

DisplayMetrics = autoclass('android.util.DisplayMetrics')
metrics = DisplayMetrics()
print('DPI', metrics.getDeviceDensity())

Env variables are :

JAVA_HOME=/usr/local/openjdk-11
JVM_PATH=/usr/lib/jvm/java-11-openjdk-arm64/lib/server/libjvm.so

When I run the container I get the error :

Traceback (most recent call last):
  File "/myapp/app2.py", line 2, in <module>
    DisplayMetrics = autoclass('android.util.DisplayMetrics')
  File "/usr/local/lib/python3.9/dist-packages/pyjnius-1.6.1-py3.9-linux-aarch64.egg/jnius/reflect.py", line 209, in autoclass
    c = find_javaclass(clsname)
  File "jnius/jnius_export_func.pxi", line 22, in jnius.find_javaclass
  File "jnius/jnius_utils.pxi", line 79, in jnius.check_exception
jnius.JavaException: JVM exception occurred: android/util/DisplayMetrics java.lang.NoClassDefFoundError

Sound normal to me as internal JVM has nothing to do with Android.

So I changed JAVA_HOME with Dalvikvm (adding -v /bin:/bin to the docker command)

JAVA_HOME=/system/bin/dalvikvm

But I got the same error.
Last, I tested with :

JVM_PATH=/system/apex/com.android.art/lib64/libopenjdkjvm.so

But I got :

Traceback (most recent call last):
  File "/myapp/pyjnius/../app3.py", line 1, in <module>
    from jnius import autoclass
  File "/usr/local/lib/python3.9/dist-packages/pyjnius-1.6.1-py3.9-linux-aarch64.egg/jnius/__init__.py", line 45, in <module>
    from .reflect import *  # noqa
  File "/usr/local/lib/python3.9/dist-packages/pyjnius-1.6.1-py3.9-linux-aarch64.egg/jnius/reflect.py", line 19, in <module>
    class Class(JavaClass, metaclass=MetaJavaClass):
  File "jnius/jnius_export_class.pxi", line 117, in jnius.MetaJavaClass.__new__
    meta.resolve_class(classDict)
  File "jnius/jnius_export_class.pxi", line 177, in jnius.MetaJavaClass.resolve_class
    cdef JNIEnv *j_env = get_jnienv()
  File "jnius/jnius_env.pxi", line 11, in jnius.get_jnienv
    default_env = get_platform_jnienv()
  File "jnius/jnius_jvm_dlopen.pxi", line 95, in jnius.get_platform_jnienv
    create_jnienv()
  File "jnius/jnius_jvm_dlopen.pxi", line 62, in jnius.create_jnienv
    raise SystemError("Error calling dlopen({0}): {1}".format(lib_path, dlerror()))
SystemError: Error calling dlopen(b'/system/apex/com.android.art/lib64/libopenjdkjvm.so'): b'/usr/lib/aarch64-linux-gnu/libc.so: invalid ELF header'

I guess that libc (used by Python/pyjnius) is not able to load Bionic linked ELF files.

BTW, I'am totally new to kivy/pyjnius and how this all works. I even don't know if it's possible to do that or not !

Any clues/help would be great !

Thx,
V.