Failed to start cloud-init at startup after upgrading to Python 3.6

Question

I've installed Python 3.6 instead of the default 3.5 release on a new cloud server (Ubuntu 16.04). After I restarted the server, I found that it failed to execute cloud-init at startup with the following errors in the syslog.

Sep 20 16:16:14 cloud-init[1310]: Traceback (most recent call last):
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/bin/cloud-init", line 9, in <module>
Sep 20 16:16:14 cloud-init[1310]:     load_entry_point('cloud-init==0.7.9', 'console_scripts', 'cloud-init')()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 570, in load_entry_point
Sep 20 16:16:14 cloud-init[1310]:     return get_distribution(dist).load_entry_point(group, name)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2751, in load_entry_point
Sep 20 16:16:14 cloud-init[1310]:     return ep.load()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2405, in load
Sep 20 16:16:14 cloud-init[1310]:     return self.resolve()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2411, in resolve
Sep 20 16:16:14 cloud-init[1310]:     module = __import__(self.module_name, fromlist=['__name__'], level=0)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 27, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from cloudinit import stages
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 21, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from cloudinit.handlers import cloud_config as cc_part
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/handlers/cloud_config.py", line 11, in <module>
Sep 20 16:16:14 cloud-init[1310]:     import jsonpatch
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/jsonpatch.py", line 114, in <module>
Sep 20 16:16:14 cloud-init[1310]:     json.load = get_loadjson()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/jsonpatch.py", line 108, in get_loadjson
Sep 20 16:16:14 cloud-init[1310]:     argspec = inspect.getargspec(json.load)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3.6/inspect.py", line 1072, in getargspec
Sep 20 16:16:14 cloud-init[1310]:     raise ValueError("Function has keyword-only parameters or annotations"
Sep 20 16:16:14 cloud-init[1310]: ValueError: Function has keyword-only parameters or annotations, use getfullargspec() API which can support them
Sep 20 16:16:14 cloud-init[1310]: Error in sys.excepthook:
Sep 20 16:16:14 cloud-init[1310]: Traceback (most recent call last):
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
Sep 20 16:16:14 cloud-init[1310]:     from apport.fileutils import likely_packaged, get_recent_crashes
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from apport.report import Report
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>
Sep 20 16:16:14 cloud-init[1310]:     import apport.fileutils
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from apport.packaging_impl import impl as packaging
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 23, in <module>
Sep 20 16:16:14 cloud-init[1310]:     import apt
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in <module>
Sep 20 16:16:14 cloud-init[1310]:     import apt_pkg
Sep 20 16:16:14 cloud-init[1310]: ModuleNotFoundError: No module named 'apt_pkg'
Sep 20 16:16:14 cloud-init[1310]: Original exception was:
Sep 20 16:16:14 cloud-init[1310]: Traceback (most recent call last):
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/bin/cloud-init", line 9, in <module>
Sep 20 16:16:14 cloud-init[1310]:     load_entry_point('cloud-init==0.7.9', 'console_scripts', 'cloud-init')()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 570, in load_entry_point
Sep 20 16:16:14 cloud-init[1310]:     return get_distribution(dist).load_entry_point(group, name)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2751, in load_entry_point
Sep 20 16:16:14 cloud-init[1310]:     return ep.load()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2405, in load
Sep 20 16:16:14 cloud-init[1310]:     return self.resolve()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/local/lib/python3.6/dist-packages/pkg_resources/__init__.py", line 2411, in resolve
Sep 20 16:16:14 cloud-init[1310]:     module = __import__(self.module_name, fromlist=['__name__'], level=0)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 27, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from cloudinit import stages
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 21, in <module>
Sep 20 16:16:14 cloud-init[1310]:     from cloudinit.handlers import cloud_config as cc_part
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/cloudinit/handlers/cloud_config.py", line 11, in <module>
Sep 20 16:16:14 cloud-init[1310]:     import jsonpatch
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/jsonpatch.py", line 114, in <module>
Sep 20 16:16:14 cloud-init[1310]:     json.load = get_loadjson()
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3/dist-packages/jsonpatch.py", line 108, in get_loadjson
Sep 20 16:16:14 cloud-init[1310]:     argspec = inspect.getargspec(json.load)
Sep 20 16:16:14 cloud-init[1310]:   File "/usr/lib/python3.6/inspect.py", line 1072, in getargspec
Sep 20 16:16:14 cloud-init[1310]:     raise ValueError("Function has keyword-only parameters or annotations"
Sep 20 16:16:14 cloud-init[1310]: ValueError: Function has keyword-only parameters or annotations, use getfullargspec() API which can support them
Sep 20 16:16:14 systemd[1]: Started MySQL Community Server.
Sep 20 16:16:14 systemd[1]: cloud-config.service: Main process exited, code=exited, status=1/FAILURE
Sep 20 16:16:14 systemd[1]: Failed to start Apply the settings specified in cloud-config.
Sep 20 16:16:14 systemd[1]: cloud-config.service: Unit entered failed state.
Sep 20 16:16:14 systemd[1]: cloud-config.service: Failed with result 'exit-code'.

There were apparently two problems:

ModuleNotFoundError: No module named 'apt_pkg'

ValueError: Function has keyword-only parameters or annotations, use getfullargspec() API which can support them

So I ran apt-get install python3-apt, but the package was already installed. Then I ran apt-get install python3-jsonpatch, and it's done successfully. Unfortunately, the problem is not fixed.

Answer 1

Finally I solved the problem by upgrading the jsonpatch package with pip.

$ pip3 install --upgrade jsonpatch

This is a known bug (compatibility issue) on an old version of jsonpatch (see https://github.com/stefankoegl/python-json-patch/issues/56). I have to upgrade the package by pip instead of apt-get. This can fix both two errors.