1. After installing mitmproxy run it (just type mitmproxy) in a terminal session and quit. This will create the necessaries certificates files at ~/.mitmproxy.

2. Extract the certificate to .crt format:
   openssl x509 -in ~/.mitmproxy/mitmproxy-ca.pem -inform PEM -out ca.crt

3. Trust the certificate into CA:
   sudo trust anchor ca.crt

4. Run the mitmproxy again

5. Open another terminal session and set the proxy:

export http_proxy='http://localhost:8080'
export https_proxy='http://localhost:8080'

6. Run a curl to an https site and it should work:
   curl https://www.google.com