stages/rpm: generate and report package metadata

Generate and report metadata about all the packages that were
installed. This information will be needed by composer, especially
the 'sigmd5' bit, for integration with koji[1].

[1] https://docs.pagure.org/koji/content_generator_metadata/

stages/org.osbuild.rpm

@@ -32,6 +32,7 @@ import sys
 import tempfile
 
 import osbuild.sources
+from osbuild import api
 
 
 SCHEMA = """
@@ -84,6 +85,32 @@ def packages_from_legacy(legacy):
     return packages
 
 
+def generate_package_metadata(tree):
+    query = r"""\{
+    "name": "%{NAME}",
+    "version": "%{VERSION}",
+    "release": "%{RELEASE}",
+    "epoch": %|EPOCH?{"%{EPOCH}"}:{null}|,
+    "arch": %|ARCH?{"%{ARCH}"}:{null}|,
+    "sigmd5": %|SIGMD5?{"%{SIGMD5}"}:{null}|
+    \},
+    """
+
+    cmd = [
+        "rpm",
+        "-qa",
+        "--root", tree,
+        "--qf=" + query
+    ]
+
+    res = subprocess.run(cmd, stdout=subprocess.PIPE,
+                         check=True, encoding="utf-8")
+
+    raw = res.stdout.strip()
+    jsdata = '{"packages": [' + raw[:-1] + "]}"
+    return json.loads(jsdata)
+
+
 def main(tree, sources, options):
     packages = packages_from_legacy(options.get("packages", []))
     checksums = [p["checksum"] for p in packages]
@@ -154,6 +181,10 @@ def main(tree, sources, options):
     with contextlib.suppress(FileNotFoundError):
         os.unlink(f"{tree}/var/lib/systemd/random-seed")
 
+    # generate the metadata
+    md = generate_package_metadata(tree)
+    api.metadata(md)
+
     return 0