Support parsing ini files with no sections

Services such as Zookeeper and Kafka use ini files which do not
explicitly specify sections. This change supports merging ini
files with no sections, so that the configuration for these
services follows the example configuration provided for them
as closely as possible.

Closes-Bug: #1756101
Partially-Implements: blueprint monasca-roles
Change-Id: I1061729875e5545c7af7d80779f9c2124b6c7134

ansible/action_plugins/merge_configs.py

@@ -25,6 +25,8 @@ from six import StringIO
 
 from oslo_config import iniparser
 
+_ORPHAN_SECTION = 'TEMPORARY_ORPHAN_VARIABLE_SECTION'
+
 
 class OverrideConfigParser(iniparser.BaseParser):
 
@@ -34,6 +36,8 @@ class OverrideConfigParser(iniparser.BaseParser):
         self._cur_section = None
 
     def assignment(self, key, value):
+        if self._cur_section is None:
+            self.new_section(_ORPHAN_SECTION)
         cur_value = self._cur_section.get(key)
         if len(value) == 1 and value[0] == '':
             value = []
@@ -44,6 +48,7 @@ class OverrideConfigParser(iniparser.BaseParser):
 
     def parse(self, lineiter):
         self._cur_sections = collections.OrderedDict()
+        self._cur_section = None
         super(OverrideConfigParser, self).parse(lineiter)
 
         # merge _cur_sections into _sections
@@ -77,7 +82,8 @@ class OverrideConfigParser(iniparser.BaseParser):
                 write_key_value(key, values)
 
         for section in self._sections:
-            fp.write('[{}]\n'.format(section))
+            if section != _ORPHAN_SECTION:
+                fp.write('[{}]\n'.format(section))
             write_section(self._sections[section])
             fp.write('\n')
 

tests/test_merge_config.py

@@ -86,11 +86,68 @@ c_key2 = 1 2 3
 
 '''
 
+TESTA_NO_SECTIONS = '''key1 = a
+key2 = b
+
+'''
+
+TESTB_NO_SECTIONS = '''key3 = c
+
+'''
+
+# TESTA_NO_SECTIONS and TESTB_NO_SECTIONS combined
+TESTC_NO_SECTIONS = '''key1 = a
+key2 = b
+key3 = c
+
+'''
+
+TESTA_NO_DEFAULT_SECTION = '''key1 = a
+key2 = b
+
+[a]
+key1 = not_a
+
+[b]
+key3 = not_c
+
+'''
+
+TESTB_NO_DEFAULT_SECTION = '''key3 = c
+
+[b]
+key2 = not_b
+key3 = override
+
+'''
+
+# TESTA_NO_DEFAULT_SECTION and TESTB_NO_DEFAULT_SECTION combined
+TESTC_NO_DEFAULT_SECTION = '''key1 = a
+key2 = b
+key3 = c
+
+[a]
+key1 = not_a
+
+[b]
+key3 = override
+key2 = not_b
+
+'''
+
 
 class OverrideConfigParserTest(base.BaseTestCase):
 
     def test_read_write(self):
-        for ini in [TESTA, TESTB, TESTC]:
+        for ini in [TESTA,
+                    TESTB,
+                    TESTC,
+                    TESTA_NO_SECTIONS,
+                    TESTB_NO_SECTIONS,
+                    TESTC_NO_SECTIONS,
+                    TESTA_NO_DEFAULT_SECTION,
+                    TESTB_NO_DEFAULT_SECTION,
+                    TESTC_NO_DEFAULT_SECTION]:
             parser = merge_configs.OverrideConfigParser()
             parser.parse(StringIO(ini))
             output = StringIO()
@@ -106,3 +163,21 @@ class OverrideConfigParserTest(base.BaseTestCase):
         parser.write(output)
         self.assertEqual(TESTC, output.getvalue())
         output.close()
+
+    def test_merge_no_sections(self):
+        parser = merge_configs.OverrideConfigParser()
+        parser.parse(StringIO(TESTA_NO_SECTIONS))
+        parser.parse(StringIO(TESTB_NO_SECTIONS))
+        output = StringIO()
+        parser.write(output)
+        self.assertEqual(TESTC_NO_SECTIONS, output.getvalue())
+        output.close()
+
+    def test_merge_no_default_section(self):
+        parser = merge_configs.OverrideConfigParser()
+        parser.parse(StringIO(TESTA_NO_DEFAULT_SECTION))
+        parser.parse(StringIO(TESTB_NO_DEFAULT_SECTION))
+        output = StringIO()
+        parser.write(output)
+        self.assertEqual(TESTC_NO_DEFAULT_SECTION, output.getvalue())
+        output.close()