osbuild: assemblers are pipelines now

Convert the assembler phase of the main pipeline in the old format
into a new Pipeline that as the assembler as a stage, where the
input of that stage is the main pipeline. This removes the need of
having "assemblers" as special concepts and thus the corresponding
code in `Pipeline` is removed. The new assembler pipeline is marked
as exported, but the pipeline that builds the tree is not anymore.
Adapt the `describe` and `output` functions of the `v1` format to
handle the assembler pipeline. Also change the tests accordingly.

NB: The id reported for the assembler via `--inspect` and the result
will change as a result of this, since the assembler stage is now
the first and only stage of a new pipeline and thus has no base
anymore.

test/mod/test_fmt_v1.py

@@ -62,7 +62,6 @@ class TestFormatV1(unittest.TestCase):
         storedir = pathlib.Path(tmpdir, "store")
         monitor = NullMonitor(sys.stderr.fileno())
         libdir = os.path.abspath(os.curdir)
-        print(libdir)
         store = ObjectStore(storedir)
         outdir = pathlib.Path(tmpdir, "out")
         outdir.mkdir()
@@ -94,7 +93,7 @@ class TestFormatV1(unittest.TestCase):
         # Load a pipeline and check the resulting manifest
         def check_stage(have: osbuild.Stage, want: Dict):
             self.assertEqual(have.name, want["name"])
-            self.assertEqual(have.options, want["options"])
+            self.assertEqual(have.options, want.get("options", {}))
 
         index = osbuild.meta.Index(os.curdir)
 
@@ -108,7 +107,7 @@ class TestFormatV1(unittest.TestCase):
 
         # We have to have two build pipelines and a main pipeline
         self.assertTrue(manifest.pipelines)
-        self.assertTrue(len(manifest.pipelines) == 3)
+        self.assertTrue(len(manifest.pipelines) == 4)
 
         # access the individual pipelines via their names
 
@@ -131,17 +130,19 @@ class TestFormatV1(unittest.TestCase):
 
         runner = build["runner"]
 
-        # main pipeline is the next one
+        # the main, aka 'tree', pipeline
         pl = manifest["tree"]
         have = pl.stages[0]
         want = description["pipeline"]["stages"][0]
         self.assertEqual(pl.runner, runner)
         check_stage(have, want)
 
-        # the assembler
-        have = pl.assembler
+        # the assembler pipeline
+        pl = manifest["assembler"]
+        have = pl.stages[0]
         want = description["pipeline"]["assembler"]
-        self.assertEqual(have.name, want["name"])
+        self.assertEqual(pl.runner, runner)
+        check_stage(have, want)
 
 
     def test_describe(self):

test/mod/test_monitor.py

@@ -38,10 +38,6 @@ class TapeMonitor(osbuild.monitor.BaseMonitor):
         self.counter["stages"] += 1
         self.stages.add(stage.id)
 
-    def assembler(self, assembler: osbuild.Stage):
-        self.counter["assembler"] += 1
-        self.asm = assembler.id
-
     def result(self, result: osbuild.pipeline.BuildResult):
         self.counter["result"] += 1
         self.results.add(result.id)
@@ -63,8 +59,6 @@ class TestMonitor(unittest.TestCase):
         pipeline.add_stage(info, {
             "isthisthereallife": False
         })
-        info = index.get_module_info("Assembler", "org.osbuild.noop")
-        pipeline.set_assembler(info)
 
         with tempfile.TemporaryDirectory() as tmpdir:
             storedir = os.path.join(tmpdir, "store")
@@ -84,7 +78,6 @@ class TestMonitor(unittest.TestCase):
 
             assert res
             self.assertIn(pipeline.stages[0].id, log)
-            self.assertIn(pipeline.assembler.id, log)
             self.assertIn("isthisthereallife", log)
 
     @unittest.skipUnless(test.TestBase.can_bind_mount(), "root-only")
@@ -101,8 +94,6 @@ class TestMonitor(unittest.TestCase):
         pipeline.add_stage(noop_info, {
             "isthisjustfantasy": True
         })
-        info = index.get_module_info("Assembler", "org.osbuild.noop")
-        pipeline.set_assembler(info)
 
         with tempfile.TemporaryDirectory() as tmpdir:
             storedir = os.path.join(tmpdir, "store")
@@ -119,10 +110,8 @@ class TestMonitor(unittest.TestCase):
         self.assertEqual(tape.counter["begin"], 1)
         self.assertEqual(tape.counter["finish"], 1)
         self.assertEqual(tape.counter["stages"], 2)
-        self.assertEqual(tape.counter["assembler"], 1)
         self.assertEqual(tape.counter["stages"], 2)
-        self.assertEqual(tape.counter["result"], 3)
+        self.assertEqual(tape.counter["result"], 2)
         self.assertIn(pipeline.stages[0].id, tape.stages)
-        self.assertIn(pipeline.assembler.id, tape.asm)
         self.assertIn("isthisthereallife", tape.output)
         self.assertIn("isthisjustfantasy", tape.output)