minica is incredibly useful for generating x509 certs for testing purposes, such as unit and integrated testing of ACME clients.

it would be very useful to be able to re-use existing private keys for these certificates. this way, a repo on GitHub (or other public source) does not need to create and publish new Private Keys for their tests.

i.e.

minica \
    -ca-cert pebble.minica.pem \
    -ca-key pebble.minica.key.pem \
    -domains example.com \
    -key localhost/key.pem

would create a new example.com directory with cert.pem and a symlink from key.pem to the source key.