Upgrading Seafile fails at Python module installation with pip3

Problems installing Python modules through pip3

The Seafile 7.0 to 7.1 upgrade documentation mentions the installation of several Python3 packages, using both apt and pip3 (Python's own package installation tool):

While the apt packages were installed fine, the pip3 packages fail to install:

root@seafile~# pip3 install --timeout=3600 Pillow pylibmc captcha jinja2 sqlalchemy==1.3.8 django-pylibmc django-simple-captcha python3-ldap
Collecting Pillow
[...]
    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-icrvn39g/Pillow/setup.py", line 1015, in <module>
        raise RequiredDependencyException(msg)
    __main__.RequiredDependencyException:

    The headers or library files could not be found for zlib,
    a required dependency when compiling Pillow from source.

    Please see the install instructions at:
       https://pillow.readthedocs.io/en/latest/installation.html

The installation fails and mentions that the (development) headers for the zlib library could not be found. These can be installed using apt:

root@seafile:~# apt-get install zlib1g-dev

But after this, another error showed up at the end:

root@seafile:~# pip3 install --timeout=3600 Pillow pylibmc captcha jinja2 sqlalchemy==1.3.8 django-pylibmc django-simple-captcha python3-ldap
Collecting Pillow
[...]
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-72km_1f0/Pillow/setup.py", line 1015, in <module>
        raise RequiredDependencyException(msg)
    __main__.RequiredDependencyException:

    The headers or library files could not be found for jpeg,
    a required dependency when compiling Pillow from source.

    Please see the install instructions at:
       https://pillow.readthedocs.io/en/latest/installation.html

Alright, this time the jpeg development headers are missing. Install them as well:

root@seafile:~# apt-get install libjpeg62-turbo-dev

Run the pip3 command again:

root@seafile:~# pip3 install --timeout=3600 Pillow pylibmc captcha jinja2 sqlalchemy==1.3.8 django-pylibmc django-simple-captcha python3-ldap
Collecting Pillow
[...]
    writing manifest file 'src/Pillow.egg-info/SOURCES.txt'
    running build_ext
    building 'PIL._imaging' extension
    creating build/temp.linux-x86_64-3.7
    creating build/temp.linux-x86_64-3.7/src
    building 'PIL._imagingmath' extension
    creating build/temp.linux-x86_64-3.7/src/libImaging
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include -I/usr/local/include -I/usr/include/python3.7m -c src/_imagingmath.c -o build/temp.linux-x86_64-3.7/src/_imagingmath.o
    building 'PIL._imagingmorph' extension
    unable to execute 'x86_64-linux-gnu-gcc': No such file or directory
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include -I/usr/local/include -I/usr/include/python3.7m -c src/_imagingmorph.c -o build/temp.linux-x86_64-3.7/src/_imagingmorph.o
    unable to execute 'x86_64-linux-gnu-gcc': No such file or directory
    building 'PIL._imagingtk' extension
    creating build/temp.linux-x86_64-3.7/src/Tk
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include -I/usr/local/include -I/usr/include/python3.7m -c src/_imagingtk.c -o build/temp.linux-x86_64-3.7/src/_imagingtk.o
    unable to execute 'x86_64-linux-gnu-gcc': No such file or directory
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DHAVE_LIBJPEG -DHAVE_LIBZ -DPILLOW_VERSION="9.2.0" -I/usr/include -I/usr/local/include -I/usr/include/python3.7m -c src/_imaging.c -o build/temp.linux-x86_64-3.7/src/_imaging.o
    unable to execute 'x86_64-linux-gnu-gcc': No such file or directory
    error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

    ----------------------------------------
Command "/usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-u1qt_b1z/Pillow/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-record-v1udz6aa/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-install-u1qt_b1z/Pillow/

Ugh, another error. This time the error mentions an issue with gcc. Let's install two additional packages: The Python development package and the build-essential package. The latter contains a lot of program compiling tools, such as the mentioned gcc.

root@seafile:~# apt-get install python3.7-dev build-essential

root@seafile:~# pip3 install --timeout=3600 Pillow pylibmc captcha jinja2 sqlalchemy==1.3.8 django-pylibmc django-simple-captcha python3-ldap
Collecting Pillow
[...]
Installing collected packages: Pillow, pylibmc, captcha, MarkupSafe, jinja2, sqlalchemy, django-pylibmc, typing-extensions, asgiref, pytz, sqlparse, Django, django-ranged-response, django-simple-captcha, pyasn1, python3-ldap
  Running setup.py install for Pillow ... done
  Running setup.py install for pylibmc ... done
  Running setup.py install for MarkupSafe ... done
  Running setup.py install for sqlalchemy ... done
  Running setup.py install for django-ranged-response ... done
Successfully installed Django-3.2.15 MarkupSafe-2.1.1 Pillow-9.2.0 asgiref-3.5.2 captcha-0.4 django-pylibmc-0.6.1 django-ranged-response-0.2.0 django-simple-captcha-0.5.17 jinja2-3.1.2 pyasn1-0.4.8 pylibmc-1.6.3 python3-ldap-0.9.8.4 pytz-2022.2.1 sqlalchemy-1.3.8 sqlparse-0.4.2 typing-extensions-4.3.0

Finally the required Python modules were installed.

TL;DR: You need more packages than documented

Before upgrading to Seafile 7.1, you need to install more packages than mentioned in the documentation:

root@seafile:~# apt-get install python3 python3-setuptools python3-pip memcached libmemcached-dev python3.7-dev build-essential zlib1g-dev libjpeg62-turbo-dev