我正在Raspberry Pi 4上使用docker-compose运行Docker容器，并希望使用Python中的picamera模块访问PiHQCam。我试着用这个教程让它发挥作用：https://www.losant.com/blog/how-to-access-the-raspberry-pi-camera-in-docker.然而，当试图构建图像时，它给了我一个错误：
ValueError: This system does not appear to be a Raspberry Pi
然后我尝试了自己的解决方案(见下文(，但遇到了这个错误：
picamera.exc.PiCameraMMALError: Failed to create MMAL component b'vc.camera_info': I/O error
这是我的设置：
docker-compose.yml:
version: '3.8'
services:
camera:
build: camera
image: eye_camera
devices:
- /dev/vchiq
Dockerfile:
FROM balenalib/rpi-raspbian:latest
RUN apt-get update &&
apt-get upgrade &&
apt-get install -y python3
python3-pip
WORKDIR /app
COPY requirements.txt .
RUN pip3 install -r requirements.txt
COPY . .
RUN groupadd -r -g 888 app &&
useradd -r -u 888 -g app -d /app app &&
chown -R app:app /app &&
usermod -a -G video app
USER app
CMD ["python3", "./main.py"]
main.py:
import picamera
def main():
print("Hello World!")
cam = picamera.PiCamera()
img = picamera.array.PiRGBArray(cam)
cam.capture(img)
cam.close()
if __name__ == '__main__':
main()
PiCameraMMALError发生在初始化相机时。这是完整的错误输出：
camera_1 | Hello World!
camera_1 | Traceback (most recent call last):
camera_1 | File "main.py", line 19, in <module>
camera_1 | main()
camera_1 | File "main.py", line 12, in main
camera_1 | cam = picamera.PiCamera()
camera_1 | File "/usr/local/lib/python3.7/dist-packages/picamera/camera.py", line 367, in __init__
camera_1 | with mo.MMALCameraInfo() as camera_info:
camera_1 | File "/usr/local/lib/python3.7/dist-packages/picamera/mmalobj.py", line 2346, in __init__
camera_1 | super(MMALCameraInfo, self).__init__()
camera_1 | File "/usr/local/lib/python3.7/dist-packages/picamera/mmalobj.py", line 633, in __init__
camera_1 | prefix="Failed to create MMAL component %s" % self.component_type)
camera_1 | File "/usr/local/lib/python3.7/dist-packages/picamera/exc.py", line 184, in mmal_check
camera_1 | raise PiCameraMMALError(status, prefix)
camera_1 | picamera.exc.PiCameraMMALError: Failed to create MMAL component b'vc.camera_info': I/O error
camera_1 | mmal: mmal_vc_shm_init: could not initialize vc shared memory service
camera_1 | mmal: mmal_vc_component_create: failed to initialise shm for 'vc.camera_info' (7:EIO)
camera_1 | mmal: mmal_component_create_core: could not create component 'vc.camera_info' (7)
这里出了什么问题？谢谢你的帮助！我很乐意提供更多信息：(
出于某种深不可测的原因，你需要魔法咒语"READTHEDOCS=True"；避免这个问题！以下Dockerfile在使用它的Raspberry Pi 4上运行良好，但如果没有它，Docker镜像构建将失败，并出现错误：
FROM arm32v7/python:latest
# Set in container
ENV TZ=Europe/London
# See https://github.com/waveform80/picamera/issues/578
ENV READTHEDOCS=True
COPY ./src /app
WORKDIR /app
RUN pip install --upgrade pip setuptools wheel
RUN pip install picamera
VOLUME ["/data"]
CMD ["/usr/bin/python", "camera.py"]
我用docker build命令构建了这个：
docker build -t jrcamera:latest .
并使用docker run命令运行它：
docker run --privileged=true -v /opt/vc:/opt/vc --env LD_LIBRARY_PATH=/opt/vc/lib --device /dev/vchiq -it jrcamera:latest
它在src目录中用以下python脚本camera.py运行了一个treat(复制到Docker映像中的/app(：
from time import sleep
from datetime import datetime
from picamera import PiCamera
camera = PiCamera()
camera.resolution = (1280, 720)
camera.annotate_text_size = 16 # Can be in range 6 to 160 inclusive, with default 32
MAX_ITER = 5
for iter_no in range(0,MAX_ITER):
camera.start_preview()
# It is important to sleep for at least two seconds before capturing an image,
# because this gives the cameras sensor time to sense the light levels
#
sleep(3)
# Annotate image with current datetime, to nearest millisecond
#
date_time = datetime.utcnow().strftime('%Y-%m-%d_%H-%M-%S.%f')[:-3]
camera.annotate_text = date_time
camera.capture("/data/image_{0:}.jpg".format(date_time))
camera.stop_preview()
(现在我只需要想办法将我的图像大小从710兆字节大到离谱，但这是另一个问题。(