ssh-rsa passwordless login not working

When connecting to DocEvent servers using sftp and using an ssh-rsa key for passwordless authentication, you might still be asked for a password.

For example:

% sftp -i ~/.ssh/id_rsa serviceid/username@sfs-ap-southeast-2.docevent.io
serviceid/username@sfs-ap-southeast-2.docevent.io's password: 

The expection is that the login should be passwordless.  But a password was requested!

If you execute the command with the -v parameter like so, you'll get more output, and possibly a message saying no mutual signature algorithm.  For example:

% sftp -v -i ~/.ssh/id_rsa serviceid/username@sfs-ap-southeast-2.docevent.io
... snip ...
debug1: Offering public key: ~/.ssh/id_rsa RSA SHA256:snip explicit agent
debug1: send_pubkey_test: no mutual signature algorithm

If this is the case, most likely your client is not working with ssh-rsa connections, and you need to modify your ~/.ssh/config file and add the following:

Host *.docevent.io
	PubkeyAcceptedAlgorithms +ssh-rsa

Note that the indentations are both tabs. This should fix the issue.