[16.0] fs_storage: support SSH private keys authentication

[sebalix]

SSH connections can now be done with private keys by setting the pkey+ passphrase options. Coupled with the eval_options_from_env this allows to set these ones from the environment, e.g:

{"host": "sftp.example.net", "username": "odoo", "pkey": "$SSH_KEY", "passphrase": "$SSH_PASSPHRASE", "port": 22}

[simahawk]

LG. Could we have some test cov?

[sebalix]

@simahawk what's the best approach here to test? Current module doesn't depend on paramiko, if this one is installed then fsspec can use it. To test the feature I would need to add paramiko as tests dependencies, is it OK?

Or should we put tests in a dedicated test_fs_storage_ssh module?

[sebalix]

I added an extra parameter pkey_type to force the key type (RSA, DSS, OPENSSH...).
It happens that some versions of ssh-keygen generates OPENSSH keys even with the -t rsa parameter if -m PEM is not set.
https://serverfault.com/questions/939909/ssh-keygen-does-not-create-rsa-private-key

Still need to test it a bit more.

EDIT: this doesn't work neither. Better to generate the key in a proper manner with ssh-keygen -t rsa -m PEM [...], and everything works as expected. I reverted my last changes.

[simahawk]

@simahawk what's the best approach here to test? Current module doesn't depend on paramiko, if this one is installed then fsspec can use it. To test the feature I would need to add paramiko as tests dependencies, is it OK?

Or should we put tests in a dedicated test_fs_storage_ssh module?

In fact, we are adding too many SFTP related feature to the base module... IMO we need a separated module for sftp: fs_storage_sftp.