What is wheel?
I am the current maintainer of the Spellcheck GitHub Action a GitHub Action based on [pyspelling][pyspelling]. pyspelling using LibXML2, via the library lxml.
And I am a complete Python n00b - so what could possibly go wrong.
Dependabot, is an automatic tool, which notifies of recommended updates via PRs on GitHub projects. The other day it it provided me with a PR to the Dockerfile for the repository mentioned above to Python 3.9, which is the newest stable release.
I tried pull the PR to my workstation and tried to get it to build and it failed.
Downloading lxml-4.5.1.tar.gz (4.5 MB)
ERROR: Command errored out with exit status 1:
command: /usr/local/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-3d1f9ag_/lxml/setup.py'"'"'; __file__='"'"'/tmp/pip-install-3d1f9ag_/lxml/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-q9dg2dad
cwd: /tmp/pip-install-3d1f9ag_/lxml/
Complete output (3 lines):
Building lxml version 4.5.1.
Building without Cython.
Error: Please make sure the libxml2 and libxslt development packages are installed.
----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.
The command '/bin/sh -c pip3 install -r requirements.txt' returned a non-zero code: 1
Building wheel for lxml (setup.py): started
Building wheel for lxml (setup.py): finished with status 'error'
ERROR: Command errored out with exit status 1:
command: /usr/local/bin/python -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-bk9chagz/lxml/setup.py'"'"'; __file__='"'"'/tmp/pip-install-bk9chagz/lxml/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d /tmp/pip-wheel-iymlsx1v
cwd: /tmp/pip-install-bk9chagz/lxml/
Complete output (84 lines):
Building lxml version 4.5.1.
Building without Cython.
Building against libxml2 2.9.4 and libxslt 1.1.32
running bdist_wheel
running build
running build_py
creating build
creating build/lib.linux-x86_64-3.9
creating build/lib.linux-x86_64-3.9/lxml
copying src/lxml/cssselect.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/builder.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/usedoctest.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/doctestcompare.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/pyclasslookup.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/__init__.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/sax.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/_elementpath.py -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/ElementInclude.py -> build/lib.linux-x86_64-3.9/lxml
creating build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/__init__.py -> build/lib.linux-x86_64-3.9/lxml/includes
creating build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/builder.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/usedoctest.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/_html5builder.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/formfill.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/diff.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/_setmixin.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/soupparser.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/__init__.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/_diffcommand.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/clean.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/ElementSoup.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/defs.py -> build/lib.linux-x86_64-3.9/lxml/html
copying src/lxml/html/html5parser.py -> build/lib.linux-x86_64-3.9/lxml/html
creating build/lib.linux-x86_64-3.9/lxml/isoschematron
copying src/lxml/isoschematron/__init__.py -> build/lib.linux-x86_64-3.9/lxml/isoschematron
copying src/lxml/etree.h -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/etree_api.h -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/lxml.etree.h -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/lxml.etree_api.h -> build/lib.linux-x86_64-3.9/lxml
copying src/lxml/includes/xmlerror.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/xmlparser.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/uri.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/xpath.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/relaxng.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/c14n.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/htmlparser.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/__init__.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/xinclude.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/tree.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/xmlschema.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/xslt.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/dtdvalid.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/etreepublic.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/config.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/schematron.pxd -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/etree_defs.h -> build/lib.linux-x86_64-3.9/lxml/includes
copying src/lxml/includes/lxml-version.h -> build/lib.linux-x86_64-3.9/lxml/includes
creating build/lib.linux-x86_64-3.9/lxml/isoschematron/resources
creating build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/rng
copying src/lxml/isoschematron/resources/rng/iso-schematron.rng -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/rng
creating build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl
copying src/lxml/isoschematron/resources/xsl/XSD2Schtrn.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl
copying src/lxml/isoschematron/resources/xsl/RNG2Schtrn.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl
creating build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_message.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_dsdl_include.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_skeleton_for_xslt1.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_svrl_for_xslt1.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_abstract_expand.xsl -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/readme.txt -> build/lib.linux-x86_64-3.9/lxml/isoschematron/resources/xsl/iso-schematron-xslt1
running build_ext
building 'lxml.etree' extension
creating build/temp.linux-x86_64-3.9
creating build/temp.linux-x86_64-3.9/src
creating build/temp.linux-x86_64-3.9/src/lxml
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -fPIC -DCYTHON_CLINE_IN_TRACEBACK=0 -I/usr/include/libxml2 -Isrc -Isrc/lxml/includes -I/usr/local/include/python3.9 -c src/lxml/etree.c -o build/temp.linux-x86_64-3.9/src/lxml/etree.o -w
Compile failed: command 'gcc' failed: No such file or directory
creating tmp
cc -I/usr/include/libxml2 -I/usr/include/libxml2 -c /tmp/xmlXPathInit5efyi30_.c -o tmp/xmlXPathInit5efyi30_.o
*********************************************************************************
Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed?
*********************************************************************************
error: command 'gcc' failed: No such file or directory
----------------------------------------
ERROR: Failed building wheel for lxml
ERROR: Failed building wheel for lxml
This led to the question:
what is a wheel?
I found the answer on StackOverflow
Apparently a wheel is a prebuilt version of the distribution. So if you go to pypi.org and search for lxml you can under files find a listing of available wheels.
Luckily my issue was solved by the addition of a wheel to the repository at pypi.org so I did not have to dig into building dependencies based on C libraries in Python.