The ui package contains static files and templates used in the web UI. For easier distribution they are included in the Thanos binary using go:embed.

During development it is more convenient to always use the files on disk to directly see changes without recompiling. Set the environment variable DEBUG=1 and compile Thanos for this to work. This is for development purposes only.

After making changes to any file, run make react-app before committing to update the generated static files and templates.