Hi!
I had a similar problem when testing the example of creating a snap to the httpstat utility.
When testing the example with a URL where the certificate was signed by Go Daddy Secure Certificate Authority - G2.
On my workstation where I have gdig2.pem installed CURL didn’t complain. However when testing in the snap I always encountered the unsafe site error.
I have verified that in folder ‘/snap/core/current/etc/ssl/’ there is no CA for Go Daddy!
As this folder structure is read only I decided to do the following test:
sudo mount --bind /etc/ssl /snap/core/current/etc/ssl
After that the httpstat snap example worked!
I believe this is not a fancy solution but I have not found a better way to add a CA.
Thanks,
Marcelo Módolo