It seems that Azure App Fabric currently lacks support for SSH private key authentication for SFTP connections, which is a change from the options available in the traditional Azure Data Factory.
As a workaround, you may consider:
- Using Basic Authentication with a username and password if that is an option for your SFTP source.
- Custom Integration by setting up an Azure Function or Logic App as a middle layer to handle the SFTP connection using private key authentication and then integrating it with App Fabric. This would involve more setup but can give you the flexibility needed until App Fabric adds this feature.
If this is a critical need, consider submitting feedback to Microsoft or checking with their support for any upcoming feature updates related to this.