Ubuntu: trust a new Certificate Authority

Assuming a PEM-formatted root CA certificate is in local-ca.crt, follow the steps below to install it.

Note: It is important to have the .crt extension on the file, otherwise it will not be processed.

sudo apt-get install -y ca-certificates
sudo cp local-ca.crt /usr/local/share/ca-certificates
sudo update-ca-certificates

After this point you can use Ubuntu’s tools like curl, wget or docker login to connect to local sites.

Source: https://ubuntu.com/server/docs/security-trust-store