osbuild: move osrelease parser into ./util

Reduce the clutter in our pipeline implementation and move the
os-release parser into ./osbuild/util/.

osbuild/pipeline.py

@@ -10,6 +10,7 @@ from . import buildroot
 from . import objectstore
 from . import remoteloop
 from . import sources
+from .util import osrelease
 
 
 RESET = "\033[0m"
@@ -367,38 +368,6 @@ class Pipeline:
         return results
 
 
-def describe_os(*paths):
-    """Read the Operating System Description from `os-release`
-
-    This creates a string describing the running operating-system name and
-    version. It reads the information from the path array provided as `paths`.
-    The first available file takes precedence. It must be formatted according
-    to the rules in `os-release(5)`.
-
-    The returned string uses the format `${ID}${VERSION_ID}` with all dots
-    stripped.
-    """
-    osrelease = {}
-
-    path = next((p for p in paths if os.path.exists(p)), None)
-    if path:
-        with open(path) as f:
-            for line in f:
-                line = line.strip()
-                if not line:
-                    continue
-                if line[0] == "#":
-                    continue
-                key, value = line.split("=", 1)
-                osrelease[key] = value.strip('"')
-
-    # Fetch `ID` and `VERSION_ID`. Defaults are defined in `os-release(5)`.
-    osrelease_id = osrelease.get("ID", "linux")
-    osrelease_version_id = osrelease.get("VERSION_ID", "")
-
-    return osrelease_id + osrelease_version_id.replace(".", "")
-
-
 def load_build(description, sources_options):
     pipeline = description.get("pipeline")
     if pipeline:
@@ -414,7 +383,7 @@ def load(description, sources_options):
     if build:
         build_pipeline, runner = load_build(build, sources_options)
     else:
-        build_pipeline, runner = None, "org.osbuild." + describe_os("/etc/os-release", "/usr/lib/os-release")
+        build_pipeline, runner = None, "org.osbuild." + osrelease.describe_os("/etc/os-release", "/usr/lib/os-release")
 
     pipeline = Pipeline(runner, build_pipeline)
 

osbuild/util/osrelease.py

@@ -0,0 +1,51 @@
+"""OS-Release Information
+
+This module implements handlers for the `/etc/os-release` type of files. The
+related documentation can be found in `os-release(5)`.
+"""
+
+import os
+
+
+def parse_files(*paths):
+    """Read Operating System Information from `os-release`
+
+    This creates a dictionary with information describing the running operating
+    system. It reads the information from the path array provided as `paths`.
+    The first available file takes precedence. It must be formatted according
+    to the rules in `os-release(5)`.
+    """
+    osrelease = {}
+
+    path = next((p for p in paths if os.path.exists(p)), None)
+    if path:
+        with open(path) as f:
+            for line in f:
+                line = line.strip()
+                if not line:
+                    continue
+                if line[0] == "#":
+                    continue
+                key, value = line.split("=", 1)
+                osrelease[key] = value.strip('"')
+
+    return osrelease
+
+
+def describe_os(*paths):
+    """Read the Operating System Description from `os-release`
+
+    This creates a string describing the running operating-system name and
+    version. It uses `parse_files()` underneath to acquire the requested
+    information.
+
+    The returned string uses the format `${ID}${VERSION_ID}` with all dots
+    stripped.
+    """
+    osrelease = parse_files(*paths)
+
+    # Fetch `ID` and `VERSION_ID`. Defaults are defined in `os-release(5)`.
+    osrelease_id = osrelease.get("ID", "linux")
+    osrelease_version_id = osrelease.get("VERSION_ID", "")
+
+    return osrelease_id + osrelease_version_id.replace(".", "")

test/test_osrelease.py

@@ -1,12 +1,12 @@
 import os
 import unittest
 
-import osbuild
+from osbuild.util import osrelease
 
 class TestOSRelease(unittest.TestCase):
     def test_non_existant(self):
         """Verify default os-release value, if no files are given."""
-        self.assertEqual(osbuild.pipeline.describe_os(), "linux")
+        self.assertEqual(osrelease.describe_os(), "linux")
 
     def test_describe_os(self):
         """Test host os detection. test/os-release contains the os-release files
@@ -14,4 +14,4 @@ class TestOSRelease(unittest.TestCase):
         """
         for entry in os.scandir("test/os-release"):
             with self.subTest(entry.name):
-                self.assertEqual(osbuild.pipeline.describe_os(entry.path), entry.name)
+                self.assertEqual(osrelease.describe_os(entry.path), entry.name)