passsing named 'options' argument to asyncssh.connect seems broken

I had some working code with asyncssh==2.4.2, now I upgraded to asyncssh==2.9.0 and asyncssh.connect() began to fail. The code looks like this:

opts = asyncssh.SSHClientConnectionOptions(
	keepalive_interval = 10,
	username = user,
	client_keys = keys,
	kex_algs = ...
	#and so on
)
async with asyncssh.connect(host, options = opts, config = None) as conn:
	#...

After the upgrade I began to get immediately asyncssh.misc.ConnectionLost: Connection lost, turned on debug logging and saw a Proxy command there (the one that I use in ~/.ssh/config), which means that neither config = None nor options = opts are applied now (or just config = None? I don’t know actually because the ignored config prevents the further connection). Now, if I call it like this - async with asyncssh.connect(host, config = None, **opts) as conn: - it works again. So the problems are:

• either docs are out-of-date or named options passing got broken, probably affecting config
• would be great to see in info/debug logging that some ssh config file was loaded and used (it was very confusing too see that Proxy command)

[ronf]

My pleasure - this was an interesting one. Let me know if you have any trouble with the change!

[ronf]

Ok - I’ve managed to change the model as I described above.

Previously, if an options object was passed in on the connect() and no config argument was specified when creating that object, the default SSH config file would be loaded at the time the options object was created. To avoid this, “config=None” had to be specified when creating the options. Loading the config early prevented some conditionals from being evaluated properly, since information to match those conditionals against wasn’t available yet. Also, leaving “config” unset when creating the options object meant that “config=None” in the connect() call could not be honored since the default config was already loaded before connect() was called.

With this change, the decision about whether to load the default config or not is deferred until the connect() call when config is not specified in either the options object creating or in the connect() call. This delay also means that specifying “config=None” on the connect() call now properly prevents the default config file from being loaded.

Here’s a more detailed summary of the old/new behavior:

When options is not specified at all on connect() call:

• When config is specified in connect(): Attempt to load specified config (UNCHANGED)
• When config is not specified on connect(): Attempt to load default config, if present (UNCHANGED)
• When config is explicitly set to None on connect(): Don’t load any config (UNCHANGED)

When options is specified on connect(), but no config was specified when creating options:

• When config is specified in connect(): Attempt to load specified config (CHANGED)
  • Previously, this would attempt to load the default config when options was created and then add the specified config later in connect(), but any settings from the default config would take precedence.
• When config is not specified on connect(): Attempt to load default config at connect() time, if present (CHANGED)
  • Previously this would attempt to load the default config earlier, when options was created. This meant that some conditionals in the config might not be evaluated correctly, as the information wasn’t available yet.
• When config is explicitly set to None on connect(): Don’t load any config (CHANGED)
  • Previously, the default config was already loaded when options was created and setting None here couldn’t prevent this.

When options is specified on connect() and config is specified when creating options:

• When config is specified in connect(): Attempt to load both config in options and config on connect() (UNCHANGED)
  • As before, there are limitations on this, as many config settings will get “locked in” at the time the options was created and not be affected by the additional config file loaded on the connect().
• When config is not specified on connect(): Load only the config specified in options (UNCHANGED)
• When config is explicitly set to None on connect(): Load only the config specified in options (UNCHANGED)

The documentation under connect(), listen_reverse(), and get_server_host_key() has also been updated to describe the new behavior.

This change is now available as commit 2809f70 in the “develop” branch. Feedback is welcome!