This plugin is smilar to the workingdir plugin, but it uses public key to route.
workingdir tree
├── git
│ ├── bitbucket
│ │ └── sshpiper_upstream
│ ├── github
│ │ ├── authorized_keys
│ │ ├── id_rsa
│ │ └── sshpiper_upstream
│ └── gitlab
│ └── sshpiper_upstream
├── linode....
The plugin will search across all sub directories of the username directory to see if the downstream key is in authorized_keys file.
The first matched sub directory will be used to route to the upstream.