Story #3847

Updated by milan almost 6 years ago

 Pulp lacks resolving of "RPM weak forward dependency": @Recommends@ during content association in case of e.g recursively copying RPMs between repositories, which by default is respected by @dnf@ A content gap might therefore be induced on a consumer machine when installing from a repository containing just the recursive-copy calculated dependencies of an RPM unit. This isn't a breaking discrepancy as "by definition, weak dependencies missing don't cause an unit to break": 

 The very weak/hint @Suggests@ field is out of scope "as hints are by default not processed by @dnf@": 
 Bot the weak and very weak/hint backward fields: @Supplements@ and @Enhances@ are out of scope too. 

 Publishing the weak dependencies in repository metadata is out of scope of this story as this is already supported trivially. 

 h3. Implementation 

 * the "RPM model":,#L772 needs to track the following "forward" weak dependency field    @Recommends@ 
 * the "primary XML repo metadata parsing code": has to be updated in order to populate the @Recommends@ field 

 h3. Examples 

 I've found few @Recommends@ field samples in the Fedora28--Workstation flavor "primary.xml": repodata file. The @dnf@ unit recommends installing these two items, with rich dependency conditioning: 

 <pre><code class="xml"> 
   <rpm:entry name="(/usr/bin/sqlite3 if bash-completion)"/> 
   <rpm:entry name="(python3-dbus if NetworkManager)"/> 

 h3. Notes 
 * the RPM content upload code needn't be updated as it "reuses the XML parsing code":,#L384 
 * the backwards dependencies needn't be processed because the Pulp workflow is closer to a repo closure calculation than to an actual content installation 
 * the processing of the @Recommends@ field is going to be "handled thru @libsolv@": once that PR lands 
 * weak dependencies processing can be "switched off": in @dnf@; see also: @man dnf.conf@ 
 * very weak dependencies/hints are most likely just completely ignored by @dnf@