Processing comps files

The comps file that Pungi takes as input is not really pure comps as used by tools like DNF. There are extensions used to customize how the file is processed.

The first step of Pungi processing is to retrieve the actual file. This can use anything that Exporting files from SCM supports.

Pungi extensions are arch attribute on packageref, group and environment tags. The value of this attribute is a comma separated list of architectures.

Second step Pungi performs is creating a file for each architecture. This is done by removing all elements with incompatible arch attribute. No additional clean up is performed on this file. The resulting file is only used internally for the rest of the compose process.

Third and final step is to create comps file for each Variant.Arch combination. This is the actual file that will be included in the compose. The start file is the original input file, from which all elements with incompatible architecture are removed. Then clean up is performed by removing all empty groups, removing non-existing groups from environments and categories and finally removing empty environments and categories. As a last step groups not listed in the variants file are removed.