Error like this:

Collecting misaka==2.1.1 (from -r requirements.txt (line 12))
  Downloading https://pypi.tuna.tsinghua.edu.cn/packages/fa/87/b1020510a00aba1b936477e54180b143df654c565b84936b0b3e85272cf2/misaka-2.1.1.tar.gz (125kB)
    ERROR: Complete output from command python setup.py egg_info:
    ERROR: 
        No working compiler found, or bogus compiler options passed to
        the compiler from Python's standard "distutils" module.  See
        the error messages above.  Likely, the problem is not related
        to CFFI but generic to the setup.py of any Python package that
        tries to compile C code.  (Hints: on OS/X 10.8, for errors about
        -mno-fused-madd see http://stackoverflow.com/questions/22313407/
        Otherwise, see https://wiki.python.org/moin/CompLangPython or
        the IRC channel #python on irc.freenode.net.)
    
        Trying to continue anyway.  If you are trying to install CFFI from
        a build done in a different context, you can ignore this warning.
    
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/distutils/unixccompiler.py", line 118, in _compile
        extra_postargs)
      File "/usr/local/lib/python3.7/distutils/ccompiler.py", line 909, in spawn
        spawn(cmd, dry_run=self.dry_run)
      File "/usr/local/lib/python3.7/distutils/spawn.py", line 36, in spawn
        _spawn_posix(cmd, search_path, dry_run=dry_run)
      File "/usr/local/lib/python3.7/distutils/spawn.py", line 159, in _spawn_posix
        % (cmd, exit_status))
    distutils.errors.DistutilsExecError: command 'gcc' failed with exit status 1

And my Dockerfile is here:

FROM python:3.7.3-alpine

WORKDIR /usr/src/app

COPY requirements.txt ./
RUN pip install -i https://pypi.tuna.tsinghua.edu.cn/simple --no-cache-dir -r requirements.txt

COPY . .

CMD [ "python", "./app.py" ]
EXPOSE 5000

Solution:
Run apk add to add the build tools:

FROM python:3.7.3-alpine

WORKDIR /usr/src/app

COPY requirements.txt ./
RUN apk add --no-cache --virtual .misaka_deps build-base python3-dev libffi-dev \
    && pip install -i https://pypi.tuna.tsinghua.edu.cn/simple --no-cache-dir -r requirements.txt \
    && apk del .misaka_deps

COPY . .

CMD [ "python", "./app.py" ]
EXPOSE 5000