PYCBC-1712: Use server default for replicaNumber when creating bucket

Changes
=======

- Change num_replicas default from 0 to None in CreateBucketSettings
- When num_replicas is unspecified, SDK now defers to server default (typically 1 replica)
- Add check_multi_node fixture to bucket management tests to skip on single-node clusters
- Add test_bucket_create_zero_replicas test that explicitly sets num_replicas=0 for single-node coverage
- Apply same changes to acouchbase and txcouchbase test suites

This is a breaking change from the perspective that buckets created without
specifying num_replicas will now have 1 replica (server default) instead of 0.

Change-Id: Idf3ae4b78b478fa4d52c30019081947bec79a5ac
Reviewed-on: https://review.couchbase.org/c/couchbase-python-client/+/238229
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Jared Casey <jared.casey@couchbase.com>

Author: anirudhlakhotia

acouchbase/tests/bucketmgmt_t.py

@@ -78,6 +78,15 @@ def check_custom_conflict_resolution_supported(self, cb_env):
     def check_non_deduped_history_supported(self, cb_env):
         cb_env.check_if_feature_supported('non_deduped_history')
 
+    @pytest.fixture(scope="class")
+    def num_nodes(self, cb_env):
+        return len(cb_env.cluster._cluster_info.nodes)
+
+    @pytest.fixture(scope="class")
+    def check_multi_node(self, num_nodes):
+        if num_nodes == 1:
+            pytest.skip("Test only for clusters with more than a single node.")
+
     @pytest.fixture()
     def test_bucket(self, test_buckets):
         return choice(test_buckets)
@@ -97,6 +106,7 @@ async def purge_buckets(self, cb_env, test_buckets):
         await cb_env.purge_buckets(test_buckets)
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create(self, cb_env, test_bucket):
@@ -112,6 +122,20 @@ async def test_bucket_create(self, cb_env, test_bucket):
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
+    async def test_bucket_create_zero_replicas(self, cb_env, test_bucket):
+        await cb_env.bm.create_bucket(
+            CreateBucketSettings(
+                name=test_bucket,
+                bucket_type=BucketType.COUCHBASE,
+                ram_quota_mb=100,
+                num_replicas=0))
+        bucket = await cb_env.try_n_times(10, 1, cb_env.bm.get_bucket, test_bucket)
+        assert bucket.get("num_replicas") == 0
+
+    @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
+    @pytest.mark.usefixtures("purge_buckets")
+    @pytest.mark.asyncio
     async def test_bucket_create_replica_index_true(self, cb_env, test_bucket):
         await cb_env.bm.create_bucket(
             CreateBucketSettings(
@@ -124,6 +148,7 @@ async def test_bucket_create_replica_index_true(self, cb_env, test_bucket):
         assert bucket.replica_index is True
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create_replica_index_false(self, cb_env, test_bucket):
@@ -138,6 +163,7 @@ async def test_bucket_create_replica_index_false(self, cb_env, test_bucket):
         assert bucket.replica_index is False
 
     @pytest.mark.usefixtures("check_bucket_min_durability_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create_durability(self, cb_env, test_bucket):
@@ -150,6 +176,7 @@ async def test_bucket_create_durability(self, cb_env, test_bucket):
         assert bucket["minimum_durability_level"] == min_durability
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create_fail(self, cb_env, test_bucket):
@@ -162,6 +189,7 @@ async def test_bucket_create_fail(self, cb_env, test_bucket):
             await cb_env.bm.create_bucket(settings)
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.asyncio
     async def test_bucket_drop_fail(self, cb_env, test_bucket):
         settings = CreateBucketSettings(
@@ -174,6 +202,7 @@ async def test_bucket_drop_fail(self, cb_env, test_bucket):
             await cb_env.bm.drop_bucket(test_bucket)
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_list(self, cb_env, test_buckets):
@@ -189,6 +218,7 @@ async def test_bucket_list(self, cb_env, test_buckets):
             set(map(lambda b: b.name, buckets)))
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_cluster_sees_bucket(self, cb_env, test_bucket):
@@ -203,6 +233,7 @@ async def test_cluster_sees_bucket(self, cb_env, test_bucket):
         await cb_env.try_n_times(10, 1, b.on_connect)
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_change_expiry(self, cb_env, test_bucket):
@@ -226,6 +257,7 @@ async def get_bucket_expiry_equal(name, expiry):
         await cb_env.try_n_times(10, 3, get_bucket_expiry_equal, test_bucket, timedelta(seconds=500))
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_flush(self, cb_env, test_bucket):
@@ -241,6 +273,7 @@ async def test_bucket_flush(self, cb_env, test_bucket):
         await cb_env.try_n_times(10, 3, cb_env.bm.flush_bucket, bucket.name)
 
     @pytest.mark.usefixtures("check_bucket_mgmt_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_flush_fail(self, cb_env, test_bucket):
@@ -257,6 +290,7 @@ async def test_bucket_flush_fail(self, cb_env, test_bucket):
             await cb_env.bm.flush_bucket(test_bucket)
 
     @pytest.mark.usefixtures("check_bucket_storage_backend_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_backend_default(self, cb_env, test_bucket):
@@ -273,6 +307,7 @@ async def test_bucket_backend_default(self, cb_env, test_bucket):
             assert bucket.storage_backend == StorageBackend.COUCHSTORE
 
     @pytest.mark.usefixtures("check_bucket_storage_backend_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_backend_magma(self, cb_env, test_bucket):
@@ -287,6 +322,7 @@ async def test_bucket_backend_magma(self, cb_env, test_bucket):
         assert bucket.storage_backend == StorageBackend.MAGMA
 
     @pytest.mark.usefixtures("check_bucket_storage_backend_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_backend_couchstore(self, cb_env, test_bucket):
@@ -301,6 +337,7 @@ async def test_bucket_backend_couchstore(self, cb_env, test_bucket):
         assert bucket.storage_backend == StorageBackend.COUCHSTORE
 
     @pytest.mark.usefixtures("check_bucket_storage_backend_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_backend_ephemeral(self, cb_env, test_bucket):
@@ -315,6 +352,7 @@ async def test_bucket_backend_ephemeral(self, cb_env, test_bucket):
         assert bucket.storage_backend == StorageBackend.UNDEFINED
 
     @pytest.mark.usefixtures("check_custom_conflict_resolution_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_custom_conflict_resolution(self, cb_env, test_bucket):
@@ -338,6 +376,7 @@ async def test_bucket_custom_conflict_resolution(self, cb_env, test_bucket):
                         flush_enabled=False))
 
     @pytest.mark.usefixtures("check_non_deduped_history_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create_history_retention(self, cb_env, test_bucket):
@@ -358,6 +397,7 @@ async def test_bucket_create_history_retention(self, cb_env, test_bucket):
         assert bucket.history_retention_duration == timedelta(days=1)
 
     @pytest.mark.usefixtures("check_non_deduped_history_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_create_history_retention_unsupported(self, cb_env, test_bucket):
@@ -375,6 +415,7 @@ async def test_bucket_create_history_retention_unsupported(self, cb_env, test_bu
             )
 
     @pytest.mark.usefixtures("check_non_deduped_history_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_update_history_retention(self, cb_env, test_bucket):
@@ -409,6 +450,7 @@ async def test_bucket_update_history_retention(self, cb_env, test_bucket):
         assert bucket.history_retention_duration == timedelta(minutes=10)
 
     @pytest.mark.usefixtures("check_non_deduped_history_supported")
+    @pytest.mark.usefixtures("check_multi_node")
     @pytest.mark.usefixtures("purge_buckets")
     @pytest.mark.asyncio
     async def test_bucket_update_history_retention_unsupported(self, cb_env, test_bucket):

couchbase/management/logic/buckets_logic.py

@@ -350,8 +350,7 @@ class BucketSettings(dict):
                                ParamTransform("flushEnabled", Identity(bool))),
         BidirectionalTransform("num_replicas",
                                ParamTransform("numReplicas", Identity(int)),
-                               ParamTransform("numReplicas", Identity(int)),
-                               default=0),
+                               ParamTransform("numReplicas", Identity(int))),
         BidirectionalTransform("ram_quota_mb",
                                ParamTransform("ramQuotaMB", Identity(int)),
                                ParamTransform("ramQuotaMB", Identity(int))),
@@ -418,7 +417,7 @@ def __init__(self,
                  name=None,  # type: str
                  flush_enabled=None,  # type: bool
                  ram_quota_mb=None,  # type: int
-                 num_replicas=0,  # type: int
+                 num_replicas=None,  # type: Optional[int]
                  replica_index=None,  # type: bool
                  bucket_type=None,  # type: BucketType
                  eviction_policy=None,  # type: EvictionPolicyType
@@ -458,7 +457,7 @@ def flush_enabled(self) -> bool:
 
     @property
     def num_replicas(self):
-        # type: (...) -> int
+        # type: (...) -> Optional[int]
         """NumReplicas (int) - The number of replicas for documents."""
         return self.get('replica_number')
 
@@ -572,7 +571,7 @@ def __init__(self,  # nosec
                  name=None,  # type: str
                  flush_enabled=False,  # type: bool
                  ram_quota_mb=None,  # type: int
-                 num_replicas=0,  # type: int
+                 num_replicas=None,  # type: Optional[int]
                  replica_index=None,  # type: bool
                  bucket_type=None,  # type: BucketType
                  eviction_policy=None,  # type: EvictionPolicyType
@@ -594,7 +593,8 @@ def __init__(self,  # nosec
         :param name: name of the bucket
         :param flush_enabled: whether flush is enabled
         :param ram_quota_mb: raw quota in megabytes
-        :param num_replicas: number of replicas
+        :param num_replicas: number of replicas. If not specified (None), the server's default
+            replica count will be used (typically 1).
         :param replica_index: whether this is a replica index
         :param bucket_type: type of bucket
         :param eviction_policy: policy for eviction