tools: use dnf filtering in lorax-template helper

The pylorax implementation of the template running code supports
globbing, as well as `--exclude` and `--optional` commands. These
are handled independently for each `installpkg` command, so that
requesting the installation of firmware packages in one command
together with an exclude of `*alsa` does indeed only exclude any
alsa firmware packages but not any other alsa packages. The
previous version of this script would just build an global list
for excludes which has a drastically different result because
a global exclude of "*alsa" would result in a global exclusion of
all matching packages and probably a dependency error.
Therefore, add support for dnf based filtering of packages on a
per `installpkg` command bases, very much like pylorax does.

tools/lorax-template-pkgs.py

@@ -8,56 +8,137 @@ in form of a JSON array.
 """
 
 import argparse
+import fnmatch
 import json
+import os
 import sys
+import tempfile
+
+import dnf
+import dnf.conf
+import dnf.conf.read
 
 from osbuild.util.lorax import render_template
+import osbuild.util.osrelease as ostrelease
 
 
-def main():
+class DepSolver:
+    def __init__(self, arch, relver, dirs):
+        self.base = dnf.Base()
+        self.arch = arch
+        self.basearch = dnf.rpm.basearch(arch)
+        conf = self.base.conf
+        conf.config_file_path = "/dev/null"
+        conf.persistdir = dirs["persistdir"]
+        conf.cachedir = dirs["cachedir"]
+        conf.substitutions["arch"] = arch
+        conf.substitutions["basearch"] = self.basearch
+        conf.substitutions["releasever"] = relver
+        conf.reposdir = [dirs["repodir"]]
+        self.repos = self.read_repos()
+
+    def read_repos(self):
+        conf = self.base.conf
+        reader = dnf.conf.read.RepoReader(conf, {})
+        return {r.id: r for r in reader}
+
+    def reset(self):
+        base = self.base
+        base.reset(goal=True, repos=True, sack=True)
+
+        for repo in self.repos.values():
+            base.repos.add(repo)
+
+        base.fill_sack(load_system_repo=False)
+
+    def filter(self, pkg):
+        sack = self.base.sack
+        return dnf.subject.Subject(pkg).get_best_query(sack).filter(latest=True)
+
+    def install(self, packages, excludes=None, optional=False):
+        def included(pkg):
+            for exclude in excludes or []:
+                if fnmatch.fnmatch(pkg.name, exclude):
+                    return False
+            return True
+
+        result = []
+
+        for p in packages:
+            pkgs = self.filter(p)
+            if not pkgs:
+                if optional:
+                    continue
+                raise dnf.exceptions.PackageNotFoundError("no package matched", p)
+
+            result.extend(map(lambda p: p.name, filter(included, pkgs)))
+
+        return result
+
+
+def list_packages(text, solver):
     parser = argparse.ArgumentParser()
-    parser.add_argument("--basearch", help="Set the `basearch` variable", default="x86_64")
-    parser.add_argument("--product", help="Set the `product` variable", default="fedora")
-    parser.add_argument("FILE", help="The template to process")
-    args = parser.parse_args()
-
-    variables = {
-      "basearch": args.basearch,
-      "product": args.product
-    }
-
-    txt = render_template(args.FILE, variables)
-
-    packages = []
-    optional = []
-    excludes = []
-
-    parser =  argparse.ArgumentParser()
-    parser.add_argument("--optional", action="append")
+    parser.add_argument("--optional", action="store_true", default=False)
     parser.add_argument("--except", dest="excludes", action="append")
     parser.add_argument("packages", help="The template to process", nargs="*")
 
-    for line in txt:
+    packages = []
+    for line in text:
         cmd, args = line[0], parser.parse_args(line[1:])
 
         if cmd != "installpkg":
             print(f"{cmd} ignored", file=sys.stderr)
             continue
 
-        if args.optional:
-            optional += args.optional
-        if args.excludes:
-            excludes += args.excludes
-        if args.packages:
-            packages += args.packages
+        pkgs = solver.install(args.packages, None, args.optional)
+        packages += pkgs
 
-    data = {
-        "packages": packages,
-        "optional": optional,
-        "except": excludes
+    return packages
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--basearch", help="Set the `basearch` variable", default="x86_64")
+    parser.add_argument("--product", help="Set the `product` variable", default="fedora")
+    parser.add_argument("--dnf-cache", metavar="PATH", type=os.path.abspath, default=None,
+                        help="Path to DNF cache-directory to use")
+    parser.add_argument("--repo-dir", metavar="PATH", type=os.path.abspath,
+                        default="/etc/yum.repos.d",
+                        help="Path to DNF repositories directory")
+    parser.add_argument("--os-version", metavar="PATH", default=None,
+                        help="OS version to use for dnf")
+    parser.add_argument("FILE", help="The template to process")
+    args = parser.parse_args()
+
+    variables = {
+        "basearch": args.basearch,
+        "product": args.product
     }
 
-    json.dump(data, sys.stdout, indent=2)
+    txt = render_template(args.FILE, variables)
+
+    packages = []
+
+    os_version = args.os_version
+    if not os_version:
+        release = ostrelease.parse_files(*ostrelease.DEFAULT_PATHS)
+        os_version = release["VERSION_ID"]
+
+    with tempfile.TemporaryDirectory(dir="/var/tmp") as tmp:
+        persistdir = os.path.join(tmp, "dnf-persist")
+        cachedir = args.dnf_cache or os.path.join(tmp, "dnf-cache")
+        dirs = {
+            "persistdir": persistdir,
+            "cachedir": cachedir,
+            "repodir": args.repo_dir
+        }
+
+        solver = DepSolver(args.basearch, os_version, dirs)
+        solver.reset()
+
+        packages = list_packages(txt, solver)
+
+    json.dump(packages, sys.stdout, indent=2)
 
 
 if __name__ == "__main__":