support local.conf files with no [[local]] section yet

Previously if we tried to added content to a local.conf file without a
local section, we actually inserted that content in the wrong place at
the end of the file. This fixes that, with unit tests.

Change-Id: Ib886d78ce5f3718def784db59ba9abf41bdb0e7b

devstack/dsconf.py

@@ -175,6 +175,12 @@ class LocalConf(object):
                 if in_section:
                     yield line
 
+    def _has_local_section(self):
+        for group in self.groups():
+            if group == ("local", "localrc"):
+                return True
+        return False
+
     def extract(self, group, conf, target):
         ini_file = IniFile(target)
         for section, name, value in self._conf(group, conf):
@@ -186,9 +192,28 @@ class LocalConf(object):
                 f.write(line)
 
     def _at_insert_point_local(self, name, func):
+        """Run function when we are at the right insertion point in file.
+
+        This lets us process an arbitrary file and insert content at
+        the correct point. It has a few different state flags that we
+        are looking for.
+
+        Does this file have a local section at all? If not, we need to
+        write one early in the file (this means we work with an empty
+        file, as well as a file that has only post-config sections.
+
+        Are we currently in a local section, if so, we need to write
+        out content to the end, because items added to local always
+        have to be added at the end.
+
+        Did we write out the work that we expected? If so, just blast
+        all lines to the end of the file.
+
+        """
         temp = tempfile.NamedTemporaryFile(mode='r')
         shutil.copyfile(self.fname, temp.name)
-        in_meta = False
+        in_local = False
+        has_local = self._has_local_section()
         done = False
         with open(self.fname, "w+") as writer:
             with open(temp.name) as reader:
@@ -198,11 +223,17 @@ class LocalConf(object):
                         continue
 
                     if re.match(re.escape("[[local|localrc]]"), line):
-                        in_meta = True
-                    elif in_meta and re.match(re.escape("[["), line):
+                        in_local = True
+                    elif in_local and re.match(re.escape("[["), line):
                         func(writer, None)
                         done = True
-                        in_meta = False
+                        in_local = False
+                    elif not has_local and re.match(re.escape("[["), line):
+                        writer.write("[[local|localrc]]\n")
+                        func(writer, None)
+                        done = True
+                        in_local = False
+                        has_local = True
 
                     # otherwise, just write what we found
                     writer.write(line)

devstack/tests/test_localconf_set_local.py

@@ -35,6 +35,15 @@ global_physnet_mtu=1450
 compute = auto
 """
 
+BASIC_NO_LOCAL = """
+[[post-config|$NEUTRON_CONF]]
+[DEFAULT]
+global_physnet_mtu=1450
+[[post-config|$NOVA_CONF]]
+[upgrade_levels]
+compute = auto
+"""
+
 RESULT1 = """
 [[local|localrc]]
 a=b
@@ -78,6 +87,18 @@ global_physnet_mtu=1450
 compute = auto
 """
 
+RESULT_NO_LOCAL = """
+[[local|localrc]]
+a=b
+c=d
+[[post-config|$NEUTRON_CONF]]
+[DEFAULT]
+global_physnet_mtu=1450
+[[post-config|$NOVA_CONF]]
+[upgrade_levels]
+compute = auto
+"""
+
 
 class TestLcSet(testtools.TestCase):
 
@@ -117,3 +138,21 @@ class TestLcSet(testtools.TestCase):
         with open(self._path) as f:
             content = f.read()
             self.assertEqual(content, RESULT3)
+
+
+class TestNoLocal(testtools.TestCase):
+
+    def setUp(self):
+        super(TestNoLocal, self).setUp()
+        self._path = self.useFixture(fixtures.TempDir()).path
+        self._path += "/local.conf"
+        with open(self._path, "w") as f:
+            f.write(BASIC_NO_LOCAL)
+
+    def test_set_new(self):
+        conf = dsconf.LocalConf(self._path)
+        conf.set_local("a=b")
+        conf.set_local("c=d")
+        with open(self._path) as f:
+            content = f.read()
+            self.assertEqual(content, RESULT_NO_LOCAL)