Merge lp:~marcoceppi/charm-helpers/resource-get into lp:charm-helpers

[Marco Ceppi]

Adds support for resource-get

Support resource-get command

* Returns the path of the resource as provided by resource-get <resource>
* Returns False when resource is not available
* Raises NotImplementedError for all versions of Juju which resource-get is not available

[Adam Israel (aisrael)]

Hey Marco. This looks good to me. +1

review: Approve

=== modified file 'charmhelpers/core/hookenv.py'
--- charmhelpers/core/hookenv.py	2016-03-07 12:55:39 +0000
+++ charmhelpers/core/hookenv.py	2016-03-07 18:04:29 +0000
@@ -912,6 +912,24 @@
     subprocess.check_call(cmd)
 
 
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def resource_get(name):
+    """used to fetch the resource path of the given name.
+
+    <name> must match a name of defined resource in metadata.yaml
+
+    returns either a path or False if resource not available
+    """
+    if not name:
+        return False
+
+    cmd = ['resource-get', name]
+    try:
+        return subprocess.check_output(cmd).decode('UTF-8')
+    except subprocess.CalledProcessError:
+        return False
+
+
 @cached
 def juju_version():
     """Full version string (eg. '1.23.3.1-trusty-amd64')"""

=== modified file 'tests/core/test_hookenv.py'
--- tests/core/test_hookenv.py	2016-03-07 12:54:54 +0000
+++ tests/core/test_hookenv.py	2016-03-07 18:04:29 +0000
@@ -1160,6 +1160,21 @@
             self.assertEqual(hookenv.charm_dir(), '/var/empty')
 
     @patch('subprocess.check_output')
+    def test_resource_get_unsupported(self, check_output_):
+        check_output_.side_effect = OSError(2, 'resource-get')
+        self.assertRaises(NotImplementedError, hookenv.resource_get, 'foo')
+
+    @patch('subprocess.check_output')
+    def test_resource_get(self, check_output_):
+        check_output_.return_value = b'/tmp/file'
+        self.assertEqual(hookenv.resource_get('file'), '/tmp/file')
+        check_output_.side_effect = CalledProcessError(
+            1, '/foo/bin/resource-get',
+            'error: could not download resource: resource#foo/file not found')
+        self.assertFalse(hookenv.resource_get('no-file'))
+        self.assertFalse(hookenv.resource_get(None))
+
+    @patch('subprocess.check_output')
     def test_is_leader_unsupported(self, check_output_):
         check_output_.side_effect = OSError(2, 'is-leader')
         self.assertRaises(NotImplementedError, hookenv.is_leader)
@@ -1613,7 +1628,7 @@
 
     @patch('subprocess.check_output')
     def test_network_get_primary_unsupported(self, check_output):
-        '''Ensure that NotImplementedError is thrown when run on Juju < 2.0''' 
+        '''Ensure that NotImplementedError is thrown when run on Juju < 2.0'''
         check_output.side_effect = OSError(2, 'network-get')
         self.assertRaises(NotImplementedError, hookenv.network_get_primary_address,
                           'mybinding')