$ openssl genrsa -aes128 1024 > server.key
$ openssl req -new -key server.key > server.csr
$ openssl x509 -in server.csr -days 365 -req -signkey server.key > server.crt
$ flask run --cert server.crt --key server.key
: * Serving Flask app "server" (lazy loading) * Environment: development * Debug mode: on * Running on https://127.0.0.1:5000/ (Press CTRL+C to quit) * Restarting with stat * Debugger is active! * Debugger PIN: xxx-xxx-xxx Enter PEM pass phrase: