Buildozer error for an Android app written with kivy, openCV, python and it uses camera

Question

I used from a code in internet that it's an kivy app that it use from camera of device (phone or laptop) here is the code:

__author__ = 'bunkus'

from kivy.app import App

from kivy.uix.widget import Widget

from kivy.uix.boxlayout import BoxLayout

from kivy.uix.image import Image

from kivy.clock import Clock

from kivy.graphics.texture import Texture

import cv2

from kivy.lang import Builder 


class CamApp(App):

    def build(self):
        self.img1=Image()
        layout = BoxLayout()
        layout.add_widget(self.img1)
        #opencv2 stuffs
        self.capture = cv2.VideoCapture(0)
        cv2.namedWindow("CV2 Image")
        Clock.schedule_interval(self.update, 1.0/33.0)
        return layout

    def update(self, dt):
        # display image from cam in opencv window
        ret, frame = self.capture.read()
        cv2.imshow("CV2 Image", frame)
        # convert it to texture
        buf1 = cv2.flip(frame, 0)
        buf = buf1.tostring()
        texture1 = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr') 
        #if working on RASPBERRY PI, use colorfmt='rgba' here instead, but stick with "bgr" in blit_buffer. 
        texture1.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
        # display image from the texture
        self.img1.texture = texture1

if __name__ == '__main__':
    CamApp().run()
    cv2.destroyAllWindows()

after then I run this app succesfully in Windows, I decided to make an APK file from this code with google COALB and buildozer, so I used colab and run these codes in there:

1: !pip install buildozer
2: !pip install cython
3: !sudo apt-get install libffi-dev
4: !buildozer init

Then I changed requirements in buildozer.spec file to **python, kivy, opencv ** and ran following code in colab:

5: !buildozer -v android debug

after some minutes, I get this error:

Exception in thread background thread for pid 12137:
Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 926, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.7/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 1637, in wrap
    fn(*rgs, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 2561, in background_thread
    handle_exit_code(exit_code)
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 2265, in fn
    return self.command.handle_command_exit_code(exit_code)
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 865, in handle_command_exit_code
    raise exc
sh.ErrorReturnCode_127: 

  RAN: /content/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/libffi/armeabi-v7a__ndk_target_21/libffi/autogen.sh

  STDOUT:
/content/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/libffi/armeabi-v7a__ndk_target_21/libffi/autogen.sh: 2: exec: autoreconf: not found


  STDERR:


Traceback (most recent call last):
  File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 1260, in <module>
    main()
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/entrypoints.py", line 18, in main
    ToolchainCL()
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 709, in __init__
    getattr(self, command)(args)
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 154, in wrapper_func
    build_dist_from_args(ctx, dist, args)
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 216, in build_dist_from_args
    args, "ignore_setup_py", False
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/build.py", line 577, in build_recipes
    recipe.build_arch(arch)
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/recipes/libffi/__init__.py", line 40, in build_arch
    shprint(sh.Command('./autogen.sh'), _env=env)
  File "/content/.buildozer/android/platform/python-for-android/pythonforandroid/logger.py", line 167, in shprint
    for line in output:
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 911, in next
    self.wait()
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 841, in wait
    self.handle_command_exit_code(exit_code)
  File "/usr/local/lib/python3.7/dist-packages/sh.py", line 865, in handle_command_exit_code
    raise exc
sh.ErrorReturnCode_127: 

  RAN: /content/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/libffi/armeabi-v7a__ndk_target_21/libffi/autogen.sh

  STDOUT:
/content/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/libffi/armeabi-v7a__ndk_target_21/libffi/autogen.sh: 2: exec: autoreconf: not found


  STDERR:

 Command failed: /usr/bin/python3 -m pythonforandroid.toolchain create --dist_name=FSH --bootstrap=sdl2 --requirements=python3,kivy,opencv --arch armeabi-v7a --copy-libs --color=always --storage-dir="/content/.buildozer/android/platform/build-armeabi-v7a" --ndk-api=21
 ENVIRONMENT:
     CUDNN_VERSION = '8.0.4.30'
     PYDEVD_USE_FRAME_EVAL = 'NO'
     LD_LIBRARY_PATH = '/usr/local/nvidia/lib:/usr/local/nvidia/lib64'
     CLOUDSDK_PYTHON = 'python3'
     LANG = 'en_US.UTF-8'
     HOSTNAME = '8763b8d4778c'
     OLDPWD = '/'
     CLOUDSDK_CONFIG = '/content/.config'
     NVIDIA_VISIBLE_DEVICES = 'all'
     DATALAB_SETTINGS_OVERRIDES = '{"kernelManagerProxyPort":6000,"kernelManagerProxyHost":"172.28.0.3","jupyterArgs":["--ip=\\"172.28.0.2\\""],"debugAdapterMultiplexerPath":"/usr/local/bin/dap_multiplexer"}'
     ENV = '/root/.bashrc'
     PAGER = 'cat'
     NCCL_VERSION = '2.7.8'
     TF_FORCE_GPU_ALLOW_GROWTH = 'true'
     JPY_PARENT_PID = '47'
     NO_GCE_CHECK = 'True'
     PWD = '/content'
     HOME = '/root'
     LAST_FORCED_REBUILD = '20210420'
     CLICOLOR = '1'
     DEBIAN_FRONTEND = 'noninteractive'
     LIBRARY_PATH = '/usr/local/cuda/lib64/stubs'
     GCE_METADATA_TIMEOUT = '0'
     GLIBCPP_FORCE_NEW = '1'
     TBE_CREDS_ADDR = '172.28.0.1:8008'
     TERM = 'xterm-color'
     SHELL = '/bin/bash'
     GCS_READ_CACHE_BLOCK_SIZE_MB = '16'
     PYTHONWARNINGS = 'ignore:::pip._internal.cli.base_command'
     MPLBACKEND = 'module://ipykernel.pylab.backend_inline'
     CUDA_VERSION = '11.0.3'
     NVIDIA_DRIVER_CAPABILITIES = 'compute,utility'
     SHLVL = '1'
     PYTHONPATH = '/env/python'
     NVIDIA_REQUIRE_CUDA = ('cuda>=11.0 brand=tesla,driver>=418,driver<419 '
'brand=tesla,driver>=440,driver<441 brand=tesla,driver>=450,driver<451')
     COLAB_GPU = '0'
     GLIBCXX_FORCE_NEW = '1'
     PATH = '/root/.buildozer/android/platform/apache-ant-.9.4/bin:/usr/local/nvidia/bin:/usr/local/cuda/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbn:/bin:/tools/node/bin:/tools/google-cloud-sdk/bin:/opt/bin'
     LD_PRELOAD = '/usr/lib/x86_64-linux-gnu/libtcmalloc.so.4'
     GIT_PAGER = 'cat'
     _ = '/usr/local/bin/buildozer'
     PACKAGES_PATH = '/root/.buildozer/android/packages'
     ANDROIDSDK = '/root/.buildozer/android/platform/android-sdk'
     ANDROIDNDK = '/root/.buildozer/android/platform/android-ndk-r19c'
     ANDROIDAPI = '27'
     ANDROIDMINAPI = '21'
 
 Buildozer failed to execute the last command
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 Please read the full log, and search for it before
 raising an issue with buildozer itself.
 In case of a bug report, please add a full log with log_level = 2

Answer 1

/content/.buildozer/android/platform/build-armeabi-v7a/build/other_builds/libffi/armeabi-v7a__ndk_target_21/libffi/autogen.sh: 2: exec: autoreconf: not found

Try installing autoreconf.