Access the {% data variables.product.prodname_vscode_command_palette %} (Shift+Command+P / Ctrl+Shift+P), then start typing "add dev". Click Codespaces: Add Dev Container Configuration Files.
Click Create a new configuration.
In this example, the template repository from which you created the codespace already contains a dev container configuration, so a message is displayed telling you that the configuration file already exists. We're going to overwrite the existing configuration file, so click Continue.
Click Show All Definitions.
