Added memcache.conf option

Change-Id: Idfcb97421a5c1476b776acef94c7b997dab55aa9

etc/memcache.conf-sample

@@ -0,0 +1,5 @@
+[memcache]
+# You can use this single conf file instead of having memcache_servers set in
+# several other conf files under [filter:cache] for example. You can specify
+# multiple servers separated with commas, as in: 10.1.2.3:11211,10.1.2.4:11211
+# memcache_servers = 127.0.0.1:11211

etc/proxy-server.conf-sample

@@ -104,8 +104,10 @@ use = egg:swift#memcache
 # set log_facility = LOG_LOCAL0
 # set log_level = INFO
 # set log_headers = False
-# Default for memcache_servers is below, but you can specify multiple servers
-# with the format: 10.1.2.3:11211,10.1.2.4:11211
+# Default for memcache_servers is to try to read the property from
+# memcache.conf (see memcache.conf-sample) or lacking that file, it will
+# default to the value below. You can specify multiple servers separated with
+# commas, as in: 10.1.2.3:11211,10.1.2.4:11211
 # memcache_servers = 127.0.0.1:11211
 
 [filter:ratelimit]

swift/common/middleware/memcache.py

@@ -13,6 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
+from ConfigParser import ConfigParser, NoSectionError, NoOptionError
+
 from swift.common.memcached import MemcacheRing
 
 
@@ -23,9 +26,21 @@ class MemcacheMiddleware(object):
 
     def __init__(self, app, conf):
         self.app = app
-        self.memcache = MemcacheRing([s.strip() for s in
-            conf.get('memcache_servers', '127.0.0.1:11211').split(',')
-            if s.strip()])
+        self.memcache_servers = conf.get('memcache_servers')
+        if not self.memcache_servers:
+            path = os.path.join(conf.get('swift_dir', '/etc/swift'),
+                                'memcache.conf')
+            memcache_conf = ConfigParser()
+            if memcache_conf.read(path):
+                try:
+                    self.memcache_servers = \
+                        memcache_conf.get('memcache', 'memcache_servers')
+                except (NoSectionError, NoOptionError):
+                    pass
+        if not self.memcache_servers:
+            self.memcache_servers = '127.0.0.1:11211'
+        self.memcache = MemcacheRing(
+            [s.strip() for s in self.memcache_servers.split(',') if s.strip()])
 
     def __call__(self, env, start_response):
         env['swift.cache'] = self.memcache

test/unit/common/middleware/test_memcache.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import unittest
+from ConfigParser import NoSectionError, NoOptionError
 
 from webob import Request
 
@@ -24,6 +25,34 @@ class FakeApp(object):
     def __call__(self, env, start_response):
         return env
 
+
+class ExcConfigParser(object):
+
+    def read(self, path):
+        raise Exception('read called with %r' % path)
+
+
+class EmptyConfigParser(object):
+
+    def read(self, path):
+        return False
+
+
+class SetConfigParser(object):
+
+    def read(self, path):
+        return True
+
+    def get(self, section, option):
+        if section == 'memcache':
+            if option == 'memcache_servers':
+                return '1.2.3.4:5'
+            else:
+                raise NoOptionError(option)
+        else:
+            raise NoSectionError(option)
+
+
 def start_response(*args):
     pass
 
@@ -38,5 +67,60 @@ class TestCacheMiddleware(unittest.TestCase):
         self.assertTrue('swift.cache' in resp)
         self.assertTrue(isinstance(resp['swift.cache'], MemcacheRing))
 
+    def test_conf_default_read(self):
+        orig_parser = memcache.ConfigParser
+        memcache.ConfigParser = ExcConfigParser
+        exc = None
+        try:
+            app = memcache.MemcacheMiddleware(FakeApp(), {})
+        except Exception, err:
+            exc = err
+        finally:
+            memcache.ConfigParser = orig_parser
+        self.assertEquals(str(exc),
+            "read called with '/etc/swift/memcache.conf'")
+
+    def test_conf_set_no_read(self):
+        orig_parser = memcache.ConfigParser
+        memcache.ConfigParser = ExcConfigParser
+        exc = None
+        try:
+            app = memcache.MemcacheMiddleware(
+                    FakeApp(), {'memcache_servers': '1.2.3.4:5'})
+        except Exception, err:
+            exc = err
+        finally:
+            memcache.ConfigParser = orig_parser
+        self.assertEquals(exc, None)
+
+    def test_conf_default(self):
+        orig_parser = memcache.ConfigParser
+        memcache.ConfigParser = EmptyConfigParser
+        try:
+            app = memcache.MemcacheMiddleware(FakeApp(), {})
+        finally:
+            memcache.ConfigParser = orig_parser
+        self.assertEquals(app.memcache_servers, '127.0.0.1:11211')
+
+    def test_conf_from_extra_conf(self):
+        orig_parser = memcache.ConfigParser
+        memcache.ConfigParser = SetConfigParser
+        try:
+            app = memcache.MemcacheMiddleware(FakeApp(), {})
+        finally:
+            memcache.ConfigParser = orig_parser
+        self.assertEquals(app.memcache_servers, '1.2.3.4:5')
+
+    def test_conf_from_inline_conf(self):
+        orig_parser = memcache.ConfigParser
+        memcache.ConfigParser = SetConfigParser
+        try:
+            app = memcache.MemcacheMiddleware(
+                    FakeApp(), {'memcache_servers': '6.7.8.9:10'})
+        finally:
+            memcache.ConfigParser = orig_parser
+        self.assertEquals(app.memcache_servers, '6.7.8.9:10')
+
+
 if __name__ == '__main__':
     unittest.main()