Docker Build fails: No module markupsafe

[dmhd1]

Building the docker image of the flask app, there is a ModuleNotFoundError:

#15 2.878 Complete output from command python setup.py egg_info:
#15 2.878 Traceback (most recent call last):
#15 2.878 File "", line 1, in
#15 2.878 File "/tmp/pip-build-oynx730y/MarkupSafe/setup.py", line 61, in
#15 2.878 run_setup(True)
#15 2.878 File "/tmp/pip-build-oynx730y/MarkupSafe/setup.py", line 44, in run_setup
#15 2.878 ext_modules=ext_modules if with_binary else [],
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/init.py", line 129, in setup
#15 2.878 return distutils.core.setup(**attrs)
#15 2.878 File "/usr/lib/python3.6/distutils/core.py", line 121, in setup
#15 2.878 dist.parse_config_files()
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/dist.py", line 494, in parse_config_files
#15 2.878 ignore_option_errors=ignore_option_errors)
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 106, in parse_configuration
#15 2.878 meta.parse()
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 382, in parse
#15 2.878 section_parser_method(section_options)
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 355, in parse_section
#15 2.878 self[name] = value
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 173, in setitem
#15 2.878 value = parser(value)
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 430, in _parse_version
#15 2.878 version = self._parse_attr(value)
#15 2.878 File "/usr/lib/python3/dist-packages/setuptools/config.py", line 305, in _parse_attr
#15 2.878 module = import_module(module_name)
#15 2.878 File "/usr/lib/python3.6/importlib/init.py", line 126, in import_module
#15 2.878 return _bootstrap._gcd_import(name[level:], package, level)
#15 2.878 File "", line 994, in _gcd_import
#15 2.878 File "", line 971, in _find_and_load
#15 2.878 File "", line 953, in _find_and_load_unlocked
#15 2.878 ModuleNotFoundError: No module named 'markupsafe'

The error seems to be related to be related to this issue in the markupsafe repo. As suggested in the issue, it is resolved by updating pip.

Hence, I suggest updating pip in the dockerfile with something like
RUN pip3 install --upgrade pip