guix pull only from private channel

[Phil]

Hi all,

Two things I can't find clarified anywhere - when doing a guix pull from a
private channel which provides supplementary packages to the standard
Guix channel.

1) If the private channel is a git repo accessed via ssh it seems
necessary to add the ssh key to an ssh-agent rather than have it pick up
~/.ssh/id_rsa.  This isn't a huge problem but when the ssh key has no
passphrase the use of an agent is actually more complicated than passing
the key directly?  Is it possible to specify a key file, and if not, is
there any good reason why not (I thought perhaps it might be access via
the guix-daemon or similar at a wild guess)?

2) Assuming I use an ssh-agent to avoid issue in 1), if I want to only
pull updates from my private channel and not from the Guix channel, I
find myself doing something like the below to force Guix channel to stay 
constant:

eval `ssh-agent` && ssh-add && guix pull --commit=$(guix describe -f
json | jq -r '.[] | select(.name=="guix").commit') && guix upgrade 
my-package-name

This works, but it feels rather ugly - is there an easier way of saying
"hold guix constant, but pull in latest updates from my private
channel" - it feels like a common use-case to me?


Thanks,
Phil.