dnfjson: detect/error if no repositories are defined

This commit adds an error message if no repositories are
defined in the dnfjson query. We had the issue in
https://github.com/osbuild/bootc-image-builder/issues/922
that in a RHEL bootc-container no repositories are defined.

Here the error is quite confusing, as it complains about
error marking packages which is technically correct but
hides the root of the problem.

With this detect we can construct a more useful error
message in the higher layers.

osbuild/solver/__init__.py

@@ -40,6 +40,10 @@ class RepoError(SolverException):
     pass
 
 
+class NoReposError(SolverException):
+    pass
+
+
 class MarkingError(SolverException):
     pass
 

osbuild/solver/dnf.py

@@ -11,7 +11,15 @@ from typing import Dict, List
 import dnf
 import hawkey
 
-from osbuild.solver import DepsolveError, MarkingError, RepoError, SolverBase, modify_rootdir_path, read_keys
+from osbuild.solver import (
+    DepsolveError,
+    MarkingError,
+    NoReposError,
+    RepoError,
+    SolverBase,
+    modify_rootdir_path,
+    read_keys,
+)
 from osbuild.util.sbom.dnf import dnf_pkgset_to_sbom_pkgset
 from osbuild.util.sbom.spdx import sbom_pkgset_to_spdx2_doc
 
@@ -92,6 +100,9 @@ class DNF(SolverBase):
         except dnf.exceptions.Error as e:
             raise RepoError(e) from e
 
+        if not self.base.repos._any_enabled():
+            raise NoReposError("There are no enabled repositories")
+
         # enable module resolving
         self.base_module = dnf.module.module_base.ModuleBase(self.base)
 

osbuild/solver/dnf5.py

@@ -14,6 +14,7 @@ from libdnf5.common import QueryCmp_GLOB as GLOB
 from osbuild.solver import (
     DepsolveError,
     MarkingError,
+    NoReposError,
     RepoError,
     SolverBase,
     modify_rootdir_path,
@@ -48,6 +49,12 @@ def _invert(dct):
     return {v: k for k in dct for v in dct[k]}
 
 
+def any_repos_enabled(base):
+    """Return true if any repositories are enabled"""
+    rq = dnf5.repo.RepoQuery(base)
+    return rq.begin() != rq.end()
+
+
 class DNF5(SolverBase):
     """Solver implements package related actions
 
@@ -168,6 +175,9 @@ class DNF5(SolverBase):
         except RuntimeError as e:
             raise RepoError(e) from e
 
+        if not any_repos_enabled(self.base):
+            raise NoReposError("There are no enabled repositories")
+
         # Custom license index file path use for SBOM generation
         self.license_index_path = license_index_path