Another note to future me – how to add a custom certificate authority to Fedora CoreOS. It probably applies to other RedHat distributions as well, like RHEL, CentOS, vanilla Fedora Linux…

It’s not hard:

curl -k https://path/to/ca.pem > /etc/pki/ca-trust/source/anchors/ca.pem
update-ca-trust

If you only have the certificate in a .crt format, here’s how to convert it (stolen from this thread):

openssl x509 -in mycert.crt -out mycert.pem -outform PEM