Merge "etcd3gw: Discover API version automatically"

releasenotes/notes/etcd3gw-api-version-discovery-3e9943c73fae48d4.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    The ``etcd3gw`` driver now automatically discovers available etcd API
+    version and determines the api path. The driver detects the appropriate api
+    path before sending its first request, and the path is reused for its
+    subsequent requests. Services may need to be restarted after its backend
+    etcd server is upgraded, so that the new api path is detected.
+    The detection is skipped if the coordination backend url contains
+    the ``api_version`` query parameter or the ``ETCD3GW_API_PATH``
+    environment is set.

setup.cfg

@@ -48,7 +48,7 @@ consul =
 etcd =
   requests>=2.10.0 # Apache-2.0
 etcd3gw =
-  etcd3gw!=0.2.6,>=0.1.0 # Apache-2.0
+  etcd3gw!=0.2.6,>=2.3.0 # Apache-2.0
 zake =
   zake>=0.1.6 # Apache-2.0
 redis =

tooz/drivers/etcd3gw.py

@@ -181,7 +181,7 @@ class Etcd3Driver(coordination.CoordinationDriverCachedRunWatchers,
     ==================  =======
     Name                Default
     ==================  =======
-    api_version         v3
+    api_version         None
     ca_cert             None
     cert_key            None
     cert_cert           None
@@ -200,9 +200,6 @@ class Etcd3Driver(coordination.CoordinationDriverCachedRunWatchers,
     #: Default port used if none provided (4001 or 2379 are the common ones).
     DEFAULT_PORT = 2379
 
-    #: Default api version if none provided
-    DEFAULT_API_VERSION = "v3"
-
     GROUP_PREFIX = b"tooz/groups/"
 
     def __init__(self, member_id, parsed_url, options):
@@ -215,14 +212,18 @@ class Etcd3Driver(coordination.CoordinationDriverCachedRunWatchers,
         cert_key = options.get('cert_key')
         cert_cert = options.get('cert_cert')
         timeout = int(options.get('timeout', self.DEFAULT_TIMEOUT))
-        api_version = options.get("api_version", self.DEFAULT_API_VERSION)
+        api_version = options.get("api_version")
+        if api_version:
+            api_path = "/" + api_version + "/"
+        else:
+            api_path = None
         self.client = etcd3gw.client(host=host,
                                      port=port,
                                      protocol=protocol,
                                      ca_cert=ca_cert,
                                      cert_key=cert_key,
                                      cert_cert=cert_cert,
-                                     api_path="/" + api_version + "/",
+                                     api_path=api_path,
                                      timeout=timeout)
         self.lock_timeout = int(options.get('lock_timeout', timeout))
         self.membership_timeout = int(options.get(

tooz/tests/drivers/test_etcd3gw.py

@@ -34,8 +34,7 @@ class TestEtcd3Gw(testcase.TestCase):
                'ca_cert': None,
                'cert_key': None,
                'cert_cert': None,
-               'api_path': (
-                   "/" + etcd3gw_driver.Etcd3Driver.DEFAULT_API_VERSION + "/"),
+               'api_path': None,
                'timeout': etcd3gw_driver.Etcd3Driver.DEFAULT_TIMEOUT},
               {'coord_url': ('etcd3+https://my_host:666?ca_cert=/my/ca_cert&'
                              'cert_key=/my/cert_key&cert_cert=/my/cert_cert&'