guix deploy: Failed to read private key

[Kitty-Cricket Piapiac <kitty@piapiac.org>]

Hello Guix,

I am relatively new to this package manager & system distribution. I am 
really struggling to get `guix deploy` working. I have a simple 
`deploy.scm` that looks something like this.

   $ cat deploy.scm
   (define %os (operating-system ...))

   (define %ip "<ip>")
   (define %key "<host-key>")

   (list
     (machine
       (operating-system %os)
       (environment managed-host-environment-type)
       (configuration (machine-ssh-configuration
                        (host-name %ip)
                        (host-key %key)
                        (identity "id_ed25519")))))

When I try and run `guix deploy deploy.scm` as a regular user, I get the 
following error:

   $ guix deploy deploy.scm
   The following 1 machine will be deployed:
     <name>

   guix deploy: deploying to <name>
   guix deploy: error: failed to deploy <name>: SSH authentication 
failed for '<ip>': Failed to read private key: /home/kitty/.ssh/id_ed25519

At first I thought there may be a permissions issue, but the private key 
is there, and with seemingly the right permissions,

   $ ll /home/kitty/.ssh/id_ed25519
   -rw------- 1 kitty users 464 Feb 13 00:03 id_ed25519

and ssh-ing into the machine normally works fine,

   $ ssh root@<ip>
   Enter passphrase for key '/home/kitty/.ssh/id_ed25519':
   Last login: Mon Feb 13 17:24:54
   root@<name> ~#

so I'm not really sure what could be causing this, and I'm not sure what 
to do now to troubleshoot. Anybody run into this before, or any ideas?

Thanks,
Kitty-Cricket Piapiac