ldap3.core.exceptions.LDAPStartTLSError: automatic start_tls befored bind not successful

Bug description

A JupyterHub configuration that has worked in the past stopped working after I have pulled the newest library versions.

Expected behaviour

My previous configuration continues to work.

Actual behaviour

LDAP login leads to the exception ldap3.core.exceptions.LDAPStartTLSError: automatic start_tls befored bind not successful with the following stacktrace

[E 2020-08-10 16:12:04.735 JupyterHub web:1670] Uncaught exception POST /hub/login?next= (134.28.117.8)
    HTTPServerRequest(protocol='http', host='XXXX', method='POST', uri='/hub/login?next=', version='HTTP/1.1', remote_ip='134.28.117.8')
    Traceback (most recent call last):
      File "/opt/conda/lib/python3.6/site-packages/tornado/web.py", line 1592, in _execute
        result = yield result
      File "/opt/conda/lib/python3.6/site-packages/jupyterhub/handlers/login.py", line 81, in post
        user = await self.login_user(data)
      File "/opt/conda/lib/python3.6/site-packages/jupyterhub/handlers/base.py", line 473, in login_user
        authenticated = await self.authenticate(data)
      File "/opt/conda/lib/python3.6/site-packages/jupyterhub/auth.py", line 257, in get_authenticated_user
        authenticated = await maybe_future(self.authenticate(handler, data))
      File "/opt/conda/lib/python3.6/types.py", line 248, in wrapped
        coro = func(*args, **kwargs)
      File "/opt/conda/lib/python3.6/site-packages/ldapauthenticator/ldapauthenticator.py", line 382, in authenticate
        conn = self.get_connection(userdn, password)
      File "/opt/conda/lib/python3.6/site-packages/ldapauthenticator/ldapauthenticator.py", line 315, in get_connection
        server, user=userdn, password=password, auto_bind=auto_bind
      File "/opt/conda/lib/python3.6/site-packages/ldap3/core/connection.py", line 356, in __init__
        self._do_auto_bind()
      File "/opt/conda/lib/python3.6/site-packages/ldap3/core/connection.py", line 391, in _do_auto_bind
        raise LDAPStartTLSError(error)
    ldap3.core.exceptions.LDAPStartTLSError: automatic start_tls befored bind not successful

How to reproduce

I used the simple config lines:

c.JupyterHub.authenticator_class = 'ldapauthenticator.LDAPAuthenticator'
c.LDAPAuthenticator.server_address = 'ldaps://XXX'
c.LDAPAuthenticator.bind_dn_template = [
    "uid={username},ou=people,dc=XXX,dc=de"
]
c.LDAPAuthenticator.use_ssl = True

Your personal set up

• OS: Ubuntu
• Version: latest

[manics]

I’ve just released https://pypi.org/project/jupyterhub-ldapauthenticator/1.3.1/ with @1kastner’s PR to limit the version of ldap3. Hopefully we’ll have a proper fix soon.

[guillaumeeb]

I’ll try redeploying my Jupyterhub and pinning ldap3 lib to 2.7 version to see if it works. Thanks for the analysis.

Pinning ldap3 to 2.7 in the Python environment where the Jupyterhub is started did the trick for me.