I've tracked down the blocking use of randomness in cloud-init's python
module initialization. There are several nonblocking calls to
getrandom(), which I believe should be fine; then a blocking call in the
multiprocessing module.
# PYTHONHASHSEED=1 gdb --args /usr/bin/python3-dbg /usr/bin/cloud-init init
GNU gdb (Ubuntu 8.0.1-0ubuntu1) 8.0.1
[...]
(gdb) break getrandom
Breakpoint 1 at 0x420b90
(gdb) python
>import sys
>sys.path.append('/usr/share/doc/python3.6/examples/gdb')
>import libpython
>end
(gdb) run
Starting program: /usr/bin/python3-dbg /usr/bin/cloud-init init
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, getrandom (buffer=buffer@entry=0x7fffffff8140,
length=length@entry=2496, flags=flags@entry=1)
at ../sysdeps/unix/sysv/linux/getrandom.c:30
[...]
(gdb) cont 4
Will ignore next 3 crossings of breakpoint 1. Continuing.
[...]
-------+
ci-info: | Route | Destination | Gateway | Genmask | Interface |
Flags |
ci-info: +-------+---------------+---------------+-----------------+-----------+
-------+
ci-info: | 0 | 0.0.0.0 | 192.168.122.1 | 0.0.0.0 | ens3 |
UG |
ci-info: | 1 | 192.168.122.0 | 0.0.0.0 | 255.255.255.0 | ens3 |
U |
ci-info: | 2 | 192.168.122.1 | 0.0.0.0 | 255.255.255.255 | ens3 |
UH |
ci-info: +-------+---------------+---------------+-----------------+-----------+
-------+
/usr/lib/python3.6/logging/config.py:85: ResourceWarning: unclosed file <_io.Tex
tIOWrapper name='/var/log/cloud-init.log' mode='a' encoding='UTF-8'>
_install_loggers(cp, handlers, disable_existing_loggers)
Breakpoint 1, getrandom (buffer=buffer@entry=0x7ffff21b7340,
length=length@entry=32, flags=flags@entry=0)
at ../sysdeps/unix/sysv/linux/getrandom.c:30
30 in ../sysdeps/unix/sysv/linux/getrandom.c
(gdb) py-bt
Traceback (most recent call first):
0x7ffff6b66b20
File "/usr/lib/python3.6/multiprocessing/process.py", line 307, in __init__
self._config = {'authkey': AuthenticationString(os.urandom(32)),
File "/usr/lib/python3.6/multiprocessing/process.py", line 320, in <module>
_current_process = _MainProcess()
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
<built-in method __import__ of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 1017, in _handle_fromlist
File "/usr/lib/python3.6/multiprocessing/context.py", line 5, in <module>
from . import process
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
<built-in method __import__ of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 1017, in _handle_fromlist
File "/usr/lib/python3.6/multiprocessing/__init__.py", line 16, in <module>
from . import context
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3.6/concurrent/futures/process.py", line 53, in <module>
import multiprocessing
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3.6/concurrent/futures/__init__.py", line 17, in <module>
from concurrent.futures.process import ProcessPoolExecutor
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3.6/asyncio/base_events.py", line 17, in <module>
import concurrent.futures
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3.6/asyncio/__init__.py", line 21, in <module>
from .base_events import *
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3/dist-packages/jinja2/asyncsupport.py", line 13, in
<module>
import asyncio
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3/dist-packages/jinja2/__init__.py", line 77, in
_patch_async
from jinja2.asyncsupport import patch_all
File "/usr/lib/python3/dist-packages/jinja2/__init__.py", line 81, in <module>
_patch_async()
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "/usr/lib/python3/dist-packages/cloudinit/templater.py", line 23, in
<module>
import jinja2
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
<built-in method __import__ of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 1017, in _handle_fromlist
File
"/usr/lib/python3/dist-packages/cloudinit/config/cc_update_etc_hosts.py", line
52, in <module>
from cloudinit import templater
<built-in method exec of module object at remote 0x7ffff6bb9cd8>
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
0x7ffff6bbf580
File "/usr/lib/python3/dist-packages/cloudinit/importer.py", line 15, in
import_module
__import__(module_name)
File "/usr/lib/python3/dist-packages/cloudinit/importer.py", line 35, in
find_module
mod = import_module(full_path)
File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 751, in
_fixup_modules
mod_name, ['', type_utils.obj_name(config)], ['handle'])
File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 818, in
run_section
mostly_mods = self._fixup_modules(raw_mods)
File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 107, in
run_module_section
(which_ran, failures) = mods.run_section(full_section_name)
File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 416, in
main_init
return (init.datasource, run_module_section(mods, name, name))
File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 638, in
status_wrapper
ret = functor(name, args)
File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 2238, in
log_time
ret = func(*args, **kwargs)
File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 829, in main
get_uptime=True, func=functor, args=(name, args))
File "/usr/bin/cloud-init", line 11, in <module>
load_entry_point('cloud-init==17.1', 'console_scripts', 'cloud-init')()
(gdb)
We have the option to set the authkey to a different value post-
initialization, but there's no way to avoid using entropy when importing
this module.
** Also affects: python3.6 (Ubuntu)
Importance: Undecided
Status: New
** Changed in: python3.6 (Ubuntu)
Status: New => Triaged
** Changed in: cloud-init (Ubuntu)
Status: Incomplete => Triaged
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https://bugs.launchpad.net/bugs/1727358
Title:
cloud-init is slow to complete init on minimized images
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