Use /info to check if SLO is enabled

The functional tests have some hokey detection of SLO support that
pre-dates the /info API, but we can do better now.

Also moved the SLO check up inside the setUp method so that skipping
the SLO tests should be somewhat faster now.

Change-Id: I645718b459d794a9a97770f7162934558c94f3e8

test/functional/swift_test_client.py

@@ -208,7 +208,11 @@ class Connection(object):
 
     def make_request(self, method, path=[], data='', hdrs={}, parms={},
                      cfg={}):
-        path = self.make_path(path, cfg=cfg)
+        if not cfg.get('verbatim_path'):
+            # Set verbatim_path=True to make a request to exactly the given
+            # path, not storage path + given path. Useful for
+            # non-account/container/object requests.
+            path = self.make_path(path, cfg=cfg)
         headers = self.make_headers(hdrs, cfg=cfg)
         if isinstance(parms, dict) and parms:
             quote = urllib.quote

test/functional/tests.py

@@ -1744,6 +1744,24 @@ class TestSloEnv(object):
     def setUp(cls):
         cls.conn = Connection(config)
         cls.conn.authenticate()
+
+        if cls.slo_enabled is None:
+            status = cls.conn.make_request('GET', '/info',
+                                           cfg={'verbatim_path': True})
+            if not (200 <= status <= 299):
+                # Can't tell if SLO is enabled or not since we're running
+                # against an old cluster, so let's skip the tests instead of
+                # possibly having spurious failures.
+                cls.slo_enabled = False
+            else:
+                # Don't bother looking for ValueError here. If something is
+                # responding to a GET /info request with invalid JSON, then
+                # the cluster is broken and a test failure will let us know.
+                cluster_info = json.loads(cls.conn.response.read())
+                cls.slo_enabled = 'slo' in cluster_info
+            if not cls.slo_enabled:
+                return
+
         cls.account = Account(cls.conn, config.get('account',
                                                    config['username']))
         cls.account.delete_containers()
@@ -1753,28 +1771,6 @@ class TestSloEnv(object):
         if not cls.container.create():
             raise ResponseError(cls.conn.response)
 
-        # TODO(seriously, anyone can do this): make this use the /info API once
-        # it lands, both for detection of SLO and for minimum segment size
-        if cls.slo_enabled is None:
-            test_file = cls.container.file(".test-slo")
-            try:
-                # If SLO is enabled, this'll raise an error since
-                # X-Static-Large-Object is a reserved header.
-                #
-                # If SLO is not enabled, then this will get the usual 2xx
-                # response.
-                test_file.write(
-                    "some contents",
-                    hdrs={'X-Static-Large-Object': 'true'})
-            except ResponseError as err:
-                if err.status == 400:
-                    cls.slo_enabled = True
-                else:
-                    raise
-            else:
-                cls.slo_enabled = False
-                return
-
         seg_info = {}
         for letter, size in (('a', 1024 * 1024),
                              ('b', 1024 * 1024),