Merge ~cjwatson/ols-charm-deps:resource-warnings into ols-charm-deps:master

[Colin Watson]

Fix ResourceWarnings on Python 3

Python 3 tends to produce warnings for code along the lines of open(...).read(). Use context manager forms instead.

[Guillermo Gonzalez (verterok)]

+1

review: Approve

diff --git a/layer/ols-pg/lib/ols/postgres.py b/layer/ols-pg/lib/ols/postgres.py
index 98f9da3..55bd3a4 100644
--- a/layer/ols-pg/lib/ols/postgres.py
+++ b/layer/ols-pg/lib/ols/postgres.py
@@ -12,7 +12,8 @@ from ols import base
 
 def db_relations(only_admin=False):
     databases = layer.options().get('ols-pg', {}).get('databases', {})
-    metadata = yaml.safe_load(open('metadata.yaml').read())
+    with open('metadata.yaml') as metadata_file:
+        metadata = yaml.safe_load(metadata_file.read())
     requires = metadata.get('requires', {})
     relations = {}
 
diff --git a/layer/ols/actions/show-config b/layer/ols/actions/show-config
index 140b0b4..5ea46c2 100755
--- a/layer/ols/actions/show-config
+++ b/layer/ols/actions/show-config
@@ -17,6 +17,7 @@ for name, path in ols.base.service_paths().items():
         continue
     if os.path.isfile(path):
         contents[name + 'path'] = path
-        contents[name] = open(path).read()
+        with open(path) as f:
+            contents[name] = f.read()
 
 hookenv.action_set(contents)
diff --git a/layer/ols/reactive/ols.py b/layer/ols/reactive/ols.py
index ef0a0ed..dcc9b01 100644
--- a/layer/ols/reactive/ols.py
+++ b/layer/ols/reactive/ols.py
@@ -34,7 +34,8 @@ def install_service():
                        'Service installed, but not configured.')
     version_info = os.path.join(code_dir(), 'version-info.txt')
     if os.path.exists(version_info):
-        hookenv.application_version_set(open(version_info).read().strip())
+        with open(version_info) as version_file:
+            hookenv.application_version_set(version_file.read().strip())
     set_state('ols.service.installed')
 
 
diff --git a/layer/ols/unit_tests/test_ols.py b/layer/ols/unit_tests/test_ols.py
index 3676aae..3693574 100644
--- a/layer/ols/unit_tests/test_ols.py
+++ b/layer/ols/unit_tests/test_ols.py
@@ -359,7 +359,8 @@ class RenderTest(TestCase):
 
         changed = render.render('test.tmpl', target, context)
         self.assertTrue(changed)
-        output = open(target, 'r').read()
+        with open(target) as f:
+            output = f.read()
         self.assertEqual(output, 'bar')
         self.assertFalse(os.path.exists(target + '.tmp'))
 
@@ -372,7 +373,8 @@ class RenderTest(TestCase):
 
         changed = render.render('test.tmpl', target, context)
         self.assertTrue(changed)
-        output = open(target, 'r').read()
+        with open(target) as f:
+            output = f.read()
         self.assertEqual(output, 'bar')
         self.assertFalse(os.path.exists(target + '.tmp'))