mkosi uses a lot of different tools to do its job. By default it will use the tools available on the host, but for a more consistent build process, it's better to build a tools bundle and use that instead.
To build this locally, run:
make download verify bootstrap mkosi.tools clean build mkosi.tools
make download: Downloads cosign and syftmake verify: Verifies cosign and syft against known checksumsmake bootstrap: Builds tools tarball in bootstrap modemake mkosi.tools: Extracts the built tools into mkosi.toolsmake clean: Cleans up the build artifactsmake build: Performs a regular, full buildmake mkosi.tools: Replacesmkosi.toolsfrom step 4 with the fully built version