From fcb3d0f96f83fe18fe04e984fd4440b3b78c64b7 Mon Sep 17 00:00:00 2001
From: Dan Prince <dprince@redhat.com>
Date: Tue, 16 Dec 2014 09:42:24 -0500
Subject: [PATCH] Output useful JSON data

If you use os-apply-config to slice out a JSON blob on the command
line you'll get back a string formatted dump of a python
dictionary (or list). Ideally we would print out proper JSON text
so that other tooling (jq, etc) can post process things in a
useful manner.

This patch updates apply_config so that if an output key is
detected to be a dict or a list it is printed to stdout
in a JSON format.

Change-Id: Ibc8b21cd6922b8664ca71e9e6009c8573ea9d107
---
 os_apply_config/apply_config.py            |  5 ++++-
 os_apply_config/tests/test_apply_config.py | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/os_apply_config/apply_config.py b/os_apply_config/apply_config.py
index 5c28494..ab69b94 100755
--- a/os_apply_config/apply_config.py
+++ b/os_apply_config/apply_config.py
@@ -102,7 +102,10 @@ def print_key(
                 raise exc.ConfigException(
                     'key %s does not exist in %s' % (key, config_path))
     value_types.ensure_type(str(config), type_name)
-    print(str(config))
+    if isinstance(config, (dict, list)):
+        print(json.dumps(config))
+    else:
+        print(str(config))
 
 
 def write_file(path, obj):
diff --git a/os_apply_config/tests/test_apply_config.py b/os_apply_config/tests/test_apply_config.py
index c5a03cb..87b7b2e 100644
--- a/os_apply_config/tests/test_apply_config.py
+++ b/os_apply_config/tests/test_apply_config.py
@@ -112,6 +112,24 @@ class TestRunOSConfigApplier(testtools.TestCase):
                          self.stdout.read().strip())
         self.assertEqual('', self.logger.output)
 
+    def test_print_key_json_dict(self):
+        self.assertEqual(0, apply_config.main(
+            ['os-apply-config.py', '--metadata', self.path, '--key',
+             'database', '--type', 'raw']))
+        self.stdout.seek(0)
+        self.assertEqual(CONFIG['database'],
+                         json.loads(self.stdout.read().strip()))
+        self.assertEqual('', self.logger.output)
+
+    def test_print_key_json_list(self):
+        self.assertEqual(0, apply_config.main(
+            ['os-apply-config.py', '--metadata', self.path, '--key',
+             'l', '--type', 'raw']))
+        self.stdout.seek(0)
+        self.assertEqual(CONFIG['l'],
+                         json.loads(self.stdout.read().strip()))
+        self.assertEqual('', self.logger.output)
+
     def test_print_non_string_key(self):
         self.assertEqual(0, apply_config.main(
             ['os-apply-config.py', '--metadata', self.path, '--key',