FEATURE: Add a parameter to 'list host attr' to separate the display …

…of common and distinct attributes.

'stack list host attr display=[all|common|distinct] [hosts...] [attr=<attr>]' changes which attributes are displayed.

display=all will display all attributes for each host, grouped by host.  This is the default, traditional behavior.

display=common will display only attributes which are identical for each host, under the name '_common_'.

display=distinct will display only attributes which are *not* identical for each host.

common/src/stack/command/stack/commands/list/attr/__init__.py

@@ -215,13 +215,14 @@ def addHostAttrs(self, attributes):
 
 	def run(self, params, args):
 
-		(glob, shadow, scope, resolve, var, const) = self.fillParams([ 
+		(glob, shadow, scope, resolve, var, const, display) = self.fillParams([ 
 			('attr',   None),
 			('shadow', True),
 			('scope',  'global'),
 			('resolve', None),
 			('var', True),
-			('const', True)
+			('const', True),
+			('display', 'all'),
 		])
 
 		shadow	= self.str2bool(shadow)
@@ -327,7 +328,6 @@ def run(self, params, args):
 				# Mix in any const attributes
 				lookup[s]['const'](attributes[s])
 
-
 		targets = sorted(lookup[scope]['fn'](args))
 
 		if resolve and scope == 'host':
@@ -362,7 +362,24 @@ def run(self, params, args):
 					matches[key] = attributes[scope][o][key]
 				attributes[scope][o] = matches
 
-
+		if display != 'all' and scope == 'host':
+			host_attrs = {
+				host: {k: str(v[0]) for k,v in attributes['host'][host].items()}
+				for host in attributes['host'] if host in targets
+			}
+
+			common_attrs = set.intersection(*(set(d.items()) for d in host_attrs.values()))
+			filtered_attrs = {}
+
+			if display == 'common':
+				filtered_attrs['_common_'] = dict((k,(v, None, None)) for k,v in common_attrs)
+				targets = ['_common_']
+			elif display == 'distinct':
+				for host in host_attrs:
+					host_pairs = set(d for d in host_attrs[host].items())
+					filtered_attrs[host] = dict((k,attributes['host'][host][k]) for k,v in host_pairs.difference(common_attrs))
+
+			attributes['host'] = filtered_attrs
 
 		self.beginOutput()
 

common/src/stack/command/stack/commands/list/host/attr/__init__.py

@@ -26,6 +26,20 @@ class Command(stack.commands.list.host.command):
 	be listed.
 	</param>
 
+	<param type='string' name='display'>
+	Control which attributes are displayed for the provided
+	hosts.
+
+	'all' will display all attributes for each host, grouped
+	by host.  This is the default.
+
+	'common' will display only attributes which are identical
+	for every host.
+
+	'distinct' will display only attributes which are not
+	identical for every host.
+	</param>
+
 	<example cmd='list host attr backend-0-0'>
 	List the attributes for backend-0-0.
 	</example>

test-framework/test-suites/integration/tests/list/test_list_host_attr.py

@@ -0,0 +1,129 @@
+import json
+from operator import itemgetter
+from itertools import groupby
+
+class TestListHostAttr:
+	def test_invalid(self, host):
+		result = host.run('stack list host attr test')
+		assert result.rc == 255
+		assert result.stderr.startswith('error - ')
+
+	def test_no_args_frontend_only(self, host):
+		result = host.run('stack list host attr output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		# with no other hosts in the db, these commands produce identical output
+		result = host.run('stack list host attr localhost output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) == attr_obj
+
+		# test appliance selector, too
+		result = host.run('stack list host attr a:frontend output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) == attr_obj
+
+		# there should be exactly one host
+		assert len({row['host'] for row in attr_obj}) == 1
+
+	def test_with_backend(self, host, add_host):
+		result = host.run('stack list host attr output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		# with other hosts in the db, this will be different
+		result = host.run('stack list host attr localhost output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) != attr_obj
+
+		# test appliance selector, too
+		result = host.run('stack list host attr a:frontend output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) != attr_obj
+
+		# both selectors should work together, though
+		result = host.run('stack list host attr a:frontend a:backend output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) == attr_obj
+
+		# both hostnames specified should be the same as none by default
+		result = host.run('stack list host attr localhost backend-0-0 output-format=json')
+		assert result.rc == 0
+		json.loads(result.stdout) == attr_obj
+
+		# there should be exactly two hosts
+		assert len({row['host'] for row in attr_obj}) == 2
+
+	def test_common_with_only_frontend(self, host):
+		result = host.run('stack list host attr display=common output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		# there should be one "host" called '_common_'
+		assert len({row['host'] for row in attr_obj}) == 1
+		assert attr_obj[0]['host'] == '_common_'
+
+	def test_distinct_with_multiple_hosts(self, host, add_host):
+		result = host.run('stack list host attr display=distinct output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		host_attrs = {
+			k: {i['attr']: i['value'] for i in v}
+			for k, v in groupby(attr_obj, itemgetter('host'))
+		}
+
+		# don't hardcode FE hostname
+		fe_hostname = [h for h in host_attrs if h != 'backend-0-0'].pop()
+		assert len(host_attrs) == 2
+		assert {'backend-0-0', fe_hostname} == set(host_attrs)
+
+		# some keys will only be in common (by default)
+		assert 'Kickstart_PrivateRootPassword' not in host_attrs[fe_hostname]
+		assert 'Kickstart_PrivateRootPassword' not in host_attrs['backend-0-0']
+		# some keys will always be distinct
+		assert 'hostname' in host_attrs['backend-0-0']
+		# backend doesn't have a hostaddr here
+		assert 'hostaddr' in host_attrs[fe_hostname]
+
+		result = host.run('stack add host attr backend-0-0 attr=foo value=bar')
+		assert result.rc == 0
+
+		result = host.run('stack list host attr display=distinct output-format=json')
+		assert result.rc == 0
+		new_attr_obj = json.loads(result.stdout)
+
+		new_host_attrs = {
+			k: {i['attr']: i['value'] for i in v}
+			for k, v in groupby(new_attr_obj, itemgetter('host'))
+		}
+
+		assert len(new_host_attrs['backend-0-0']) == len(host_attrs['backend-0-0']) + 1
+		assert len(new_host_attrs[fe_hostname]) == len(host_attrs[fe_hostname])
+
+		result = host.run('stack list host attr display=common output-format=json')
+		assert result.rc == 0
+		common_attr_obj = json.loads(result.stdout)
+
+		common_host_attrs = {
+			k: {i['attr']: i['value'] for i in v}
+			for k, v in groupby(common_attr_obj, itemgetter('host'))
+		}
+
+		# the set of common attrs and distinct attrs should never overlap
+		assert set(common_host_attrs['_common_']).isdisjoint(new_host_attrs['backend-0-0'])
+
+	def test_common_with_multiple_hosts_single_attr_param(self, host, add_host):
+		result = host.run('stack list host attr display=distinct attr=hostname output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		# only two hosts, no common attrs here
+		assert len({row['host'] for row in attr_obj}) == 2
+
+		result = host.run('stack list host attr display=common attr=box output-format=json')
+		assert result.rc == 0
+		attr_obj = json.loads(result.stdout)
+
+		# by default these will resolve to the same, so only common will be listed
+		assert {row['host'] for row in attr_obj} == {'_common_'}