When you are building out a configuration for Codespaces using a dev container, the default behavior is now to do an incremental rebuild. The existing rebuild functionality is still available and has been renamed to ‘Full rebuild’.
Incremental rebuild is much faster because it builds on top of your existing docker cache, reusing common images and layers between rebuilds. This is readily apparent when adding configurations to the default container for Codespaces which is quite large.
When using VS Code, you access these commands from the command palette.
The rebuild behavior prior to this change was full rebuild, which is slower but guarantees correctness because it removes all images from the virtual machine before re-pulling even unchanged images. You may occasionally want to do this after many iterations of rebuilding your configuration, and want to free up disk space or ensure your configuration is not dependent on layers that won’t be present during a clean creation of a codespace from the configuration.