Unexpected Cookie Loading with aiohttp DummyCookieJar ?

[loic-bellinger]

Hello,

I'm using a session without cookies as follows:

aiohttp.ClientSession(
    raise_for_status=True,
    cookie_jar=aiohttp.DummyCookieJar()
)

However, I'm still receiving the following warning:
"Cannot load response cookies: Illegal key".

Could you please clarify why this is happening (or why is it better that this is happening) ?

Thanks!

[Dreamsorcerer]

Could you make a slight edit to the aiohttp code and rerun it in order to get the traceback?
In client_reqrep.py:

client_logger.warning("Can not load response cookies: %s", exc)

Just add exc_info=True to the arguments (we should probably already be doing this...).

[loic-bellinger]

Here are a few

Can not load response cookies: Illegal key 'BIGipServerF/Tfsu1wUbd+Sl/QZh+WcA'
Traceback (most recent call last):
  File "/path/to/project/.venv/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1093, in start
    self.cookies.load(hdr)
  File "/path/to/lib/python3.12/http/cookies.py", line 514, in load
    self.__parse_string(rawdata)
  File "/path/to/lib/python3.12/http/cookies.py", line 578, in __parse_string
    self.__set(key, rval, cval)
  File "/path/to/lib/python3.12/http/cookies.py", line 470, in __set
    M.set(key, real_value, coded_value)
  File "/path/to/lib/python3.12/http/cookies.py", line 335, in set
    raise CookieError('Illegal key %r' % (key,))
http.cookies.CookieError: Illegal key 'BIGipServerF/Tfsu1wUbd+Sl/QZh+WcA'
Can not load response cookies: Illegal key 'sessionDefaut-/Ces-acces-externe-TSA/pr2-tsa-vipext01.tsa.in.phm.education.gouv.fr'
Traceback (most recent call last):
  File "/path/to/project/.venv/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1093, in start
    self.cookies.load(hdr)
  File "/path/to/lib/python3.12/http/cookies.py", line 514, in load
    self.__parse_string(rawdata)
  File "/path/to/lib/python3.12/http/cookies.py", line 578, in __parse_string
    self.__set(key, rval, cval)
  File "/path/to/lib/python3.12/http/cookies.py", line 470, in __set
    M.set(key, real_value, coded_value)
  File "/path/to/lib/python3.12/http/cookies.py", line 335, in set
    raise CookieError('Illegal key %r' % (key,))
http.cookies.CookieError: Illegal key 'sessionDefaut-/Ces-acces-externe-TSA/pr2-tsa-vipext01.tsa.in.phm.education.gouv.fr'
Can not load response cookies: Illegal key 'BIGipServerx2Lrwv/jtif5Mttz+lWGRQ'
Traceback (most recent call last):
  File "/path/to/project/.venv/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1093, in start
    self.cookies.load(hdr)
  File "/path/to/lib/python3.12/http/cookies.py", line 514, in load
    self.__parse_string(rawdata)
  File "/path/to/lib/python3.12/http/cookies.py", line 578, in __parse_string
    self.__set(key, rval, cval)
  File "/path/to/lib/python3.12/http/cookies.py", line 470, in __set
    M.set(key, real_value, coded_value)
  File "/path/to/lib/python3.12/http/cookies.py", line 335, in set
    raise CookieError('Illegal key %r' % (key,))
http.cookies.CookieError: Illegal key 'BIGipServerx2Lrwv/jtif5Mttz+lWGRQ'
Can not load response cookies: Illegal key 'BIGipServerx2Lrwv/jtif5Mttz+lWGRQ'
Traceback (most recent call last):
  File "/path/to/project/.venv/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1093, in start
    self.cookies.load(hdr)
  File "/path/to/lib/python3.12/http/cookies.py", line 514, in load
    self.__parse_string(rawdata)
  File "/path/to/lib/python3.12/http/cookies.py", line 578, in __parse_string
    self.__set(key, rval, cval)
  File "/path/to/lib/python3.12/http/cookies.py", line 470, in __set
    M.set(key, real_value, coded_value)
  File "/path/to/lib/python3.12/http/cookies.py", line 335, in set
    raise CookieError('Illegal key %r' % (key,))
http.cookies.CookieError: Illegal key 'BIGipServerx2Lrwv/jtif5Mttz+lWGRQ'
Can not load response cookies: Illegal key 'BIGipServersSJ/N0htS4amrLzHZnDNIQ'
Traceback (most recent call last):
  File "/path/to/project/.venv/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1093, in start
    self.cookies.load(hdr)
  File "/path/to/lib/python3.12/http/cookies.py", line 514, in load
    self.__parse_string(rawdata)
  File "/path/to/lib/python3.12/http/cookies.py", line 578, in __parse_string
    self.__set(key, rval, cval)
  File "/path/to/lib/python3.12/http/cookies.py", line 470, in __set
    M.set(key, real_value, coded_value)
  File "/path/to/lib/python3.12/http/cookies.py", line 335, in set
    raise CookieError('Illegal key %r' % (key,))
http.cookies.CookieError: Illegal key 'BIGipServersSJ/N0htS4amrLzHZnDNIQ'

[Dreamsorcerer]

Right, I see. That is not the cookie jar on the session. The response has cookies, which is what is being loaded here. I think it makes sense that the cookies are loaded on the response object, regardless of whether they are going to be stored in the cookie jar.

[loic-bellinger]

Yes, that makes perfect sense. I mistakenly assumed—perhaps a bit naively—that using DummyCookieJar() would bypass all the overhead associated with loading and parsing cookies. However, cookies can still be needed for various reasons.

That said, perhaps a parameter to suppress certain warnings could be useful in cases where cookies are truly irrelevant to the user.

[Dreamsorcerer]

Yes, would probably be nice to suppress those errors if not needed. I don't have a concrete idea how to do it though. Feel free to take a look and come up with a proposal.