1. On laptop (macOS), clone this repo

   git clone https://github.com/syncom/mitmproxy-hermit.git
   cd mitmproxy-hermit/

2. Install mitmproxy

   brew install mitmproxy

   The CA certificate for mitmproxy has been copied from ~/.mitmproxy/mitmproxy-ca-cert.cert of the local machine to mitmproxy-ca-cert.cer of this repo. If your local mitmproxy's CA certificate is different, replace mitmproxy-ca-cert.cer in the cloned repository with yours.

3. Build Docker image for testing

   docker build --tag ubuntu:mitm .

4. Proxy Docker traffic. In Docker Desktop, Preferences/Resources/PROXIES, turn on "Manual proxy configuration", and use http://localhost:4242 as the value for "Web Server (HTTP)" and "Secure Web Server (HTTPS)". Restart Docker Desktop.

   

5. On laptop, start mitmproxy in passthrough mode.

   mitmproxy --listen-port 4242

6. Run Docker image

   docker run -it ubuntu:mitm

   Inside Docker VM shell (run as root user)

   # Install Hermit from canary channel
   curl -fsSL https://github.com/cashapp/hermit/releases/download/canary/install.sh | /bin/bash
   # Add to PATH
   export PATH="/root/bin:$PATH"
   # Show version
   hermit version # For my test run, 819b5ff (canary)
   # Run hermit init, and activate hermit
   mkdir project
   cd project
   hermit init .
   . bin/activate-hermit
   # Show version inside environment
   hermit version # For my test run same as above, 819b5ff (canary)

7. On laptop host, build custom Hermit for linux-amd64

   make GOOS=linux GOARCH=amd64 CHANNEL=canary VERSION=testversion build

   Rename build/hermit-linux-amd64.gz to test-hermit-linux-amd64.gz, and put it in the top-level directory in this repository.

8. On host, exit from mitmproxy console (press q and select yes), and run the mitmdump to override the downloaded hermit-linux-amd64.gz with the custom built one.

   mitmdump -s rewrite_file.py --listen-port 4242 | tee mitmproxy.log

9. In Docker VM shell, test hermit update in the already activated environment. This should get test-hermit-linux-amd64.gz to replace the Hermit binary.

   project🐚  hermit update
   project🐚  hermit version # Should be "testversion (canary)"
   project🐚  hermit validate env .
   project🐚  echo $? # Should be 0
   project🐚  deactivate-hermit
   # More testing with the custom Hermit
   mkdir ../project1
   cd ../project1
   hermit version # Should be "testversion (canary)"
   hermit init .
   . bin/activate-hermit
   project1🐚  hermit version # Should be "testversion (canary)"
   project1🐚  hermit validate env .
   project1🐚  echo $? # Should be 0
   # Clear cache and try custom Hermit again
   project1🐚  deactivate-hermit
   rm -rf ~/.cache/hermit
   rm -rf /root/bin/hermit*
   . bin/activate-hermit
   project1🐚  hermit version # Should be "testversion (canary)"
   project1🐚  hermit validate env .
   project1🐚  echo $? # Should be 0

Remember to revert your proxy configuration in Docker Desktop after testing is done.