dnfjson: cache cleanup

Added CleanCache() method to the solver that deletes all the caches if
the total size grows above a certain (configurable) limit
(default: 500 MiB).

The function is called externally to handle errors (usually log or
ignore completely) and to avoid calling multiple times for multiple
depsolves of a single request.

The cleanup is extremely simple and is meant as a placeholder for more
sophisticated cache management.  The goal is to simply avoid ballooning
cache sizes that might cause issues for users or our own services.

cmd/osbuild-pipeline/main.go

@@ -143,6 +143,11 @@ func main() {
 	solver := dnfjson.NewSolver(d.ModulePlatformID(), d.Releasever(), arch.Name(), path.Join(home, ".cache/osbuild-composer/rpmmd"))
 	solver.SetDNFJSONPath(findDnfJsonBin())
 
+	// Set cache size to 3 GiB
+	// osbuild-pipeline is often used to generate a lot of manifests in a row
+	// let the cache grow to fit much more repository metadata than we usually allow
+	solver.SetMaxCacheSize(3 * 1024 * 1024 * 1024)
+
 	packageSets := imageType.PackageSets(composeRequest.Blueprint, repos)
 	depsolvedSets := make(map[string][]rpmmd.PackageSpec)
 
@@ -189,4 +194,8 @@ func main() {
 		}
 	}
 	os.Stdout.Write(bytes)
+	if err := solver.CleanCache(); err != nil {
+		// print to stderr but don't exit with error
+		fmt.Fprintf(os.Stderr, "Error during rpm repo cache cleanup: %s", err.Error())
+	}
 }

cmd/osbuild-worker/jobimpl-depsolve.go

@@ -30,6 +30,7 @@ func (impl *DepsolveJobImpl) depsolve(packageSets map[string][]rpmmd.PackageSet,
 		}
 		depsolvedSets[name] = res
 	}
+
 	return depsolvedSets, nil
 }
 
@@ -66,6 +67,10 @@ func (impl *DepsolveJobImpl) Run(job worker.Job) error {
 			logWithId.Errorf("rpmmd error in depsolve job: %v", err)
 		}
 	}
+	if err := impl.Solver.CleanCache(); err != nil {
+		// log and ignore
+		logWithId.Errorf("Error during rpm repo cache cleanup: %s", err.Error())
+	}
 
 	err = job.Update(&result)
 	if err != nil {