To build CircuitPython within a Github codespace, you need to perform the following steps.

1. checkout the code to a codespace

• click on the green "<> Code"-button
• select the Codespaces-tab
• choose "+ new with options..." from the "..."-menu
• in the following screen select the branch and then
• select the port instead of "Default project configuration" (unsupported: ports not using cortex-m or esp-idf)
  
• update region as necessary
• finally, click on the green "Create codespace" button

2. Your codespace is created. Cloning the image and the repo is quite fast, but preparing it for CircuitPython-development takes about 10 minutes. But this is a one-time task: once created, your codespace exists until you explicitly delete it or until it times out (default: 30 days).
   (Technical note: due to a bug in codespace creation, the setup is triggered from $HOME/.bashrc and runs in the background).

3. During creation, you can run the command tail -f /workspaces/install_build_env.log.active to see what is going on. Once finished the log file is available as /workspaces/install_build_env.log.

4. To actually build CircuitPython, open a new terminal and run e.g.

   cd ports/raspberrypi
   make -j $(nproc) BOARD=whatever TRANSLATION=xx_XX
   

   This takes about 2m40s. The new terminal is necessary since the setup of the build environment also changes $HOME/.bashrc and sets important environment variables in that file.

As a normal user, you have 120 CPU-hours and 15GB per month free. Since the smallest machine has two CPUs, you effectively have 60 hours active time available.

All scripts are in circuitpython/.devcontainer and can also be executed manually which should usually not be necessary. With small changes, they should also work on a Linux-PC or laptop.