feat: support native asyncpg connection pools

This changed is analogous to CloudSQL's change:
GoogleCloudPlatform/cloud-sql-python-connector#1182

README.md

@@ -251,6 +251,42 @@ currently supports the following asyncio database drivers:
 
 [asyncio]: https://docs.python.org/3/library/asyncio.html
 
+#### Asyncpg Connection Pool
+
+```python
+import asyncpg
+from google.cloud.alloydb.connector import AsyncConnector
+
+async def main():
+    # initialize Connector object for connections to AlloyDB
+    connector = AsyncConnector()
+
+    # creation function to generate asyncpg connections as the 'connect' arg
+    async def getconn(instance_connection_name, **kwargs) -> asyncpg.Connection:
+        return await connector.connect(
+            instance_connection_name,
+            "asyncpg",
+            user="my-user",
+            password="my-password",
+            db="my-db",
+        )
+
+    # initialize connection pool
+    pool = await asyncpg.create_pool(
+        "projects/<YOUR_PROJECT>/locations/<YOUR_REGION>/clusters/<YOUR_CLUSTER>/instances/<YOUR_INSTANCE>",
+        connect=getconn,
+    )
+
+    # acquire connection and query AlloyDB database
+    async with pool.acquire() as conn:
+        res = await conn.fetch("SELECT NOW()")
+
+    # close Connector
+    await connector.close()
+```
+
+#### SQLAlchemy Async Engine
+
 ```python
 import asyncpg
 
@@ -260,7 +296,7 @@ from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine
 from google.cloud.alloydb.connector import AsyncConnector
 
 async def init_connection_pool(connector: AsyncConnector) -> AsyncEngine:
-    # initialize Connector object for connections to AlloyDB
+    # creation function to generate asyncpg connections as 'async_creator' arg
     async def getconn() -> asyncpg.Connection:
         conn: asyncpg.Connection = await connector.connect(
             "projects/<YOUR_PROJECT>/locations/<YOUR_REGION>/clusters/<YOUR_CLUSTER>/instances/<YOUR_INSTANCE>",
@@ -311,6 +347,39 @@ visit the [official documentation][asyncpg-docs].
 The `AsyncConnector` also may be used as an async context manager, removing the
 need for explicit calls to `connector.close()` to cleanup resources.
 
+#### Asyncpg Connection Pool
+
+```python
+import asyncpg
+from google.cloud.alloydb.connector import AsyncConnector
+
+async def main():
+    # initialize AsyncConnector object for connections to AlloyDB
+    async with AsyncConnector() as connector:
+
+        # creation function to generate asyncpg connections as the 'connect' arg
+        async def getconn(instance_connection_name, **kwargs) -> asyncpg.Connection:
+            return await connector.connect(
+                instance_connection_name,
+                "asyncpg",
+                user="my-user",
+                password="my-password",
+                db="my-db",
+            )
+
+        # create connection pool
+        pool = await asyncpg.create_pool(
+            "projects/<YOUR_PROJECT>/locations/<YOUR_REGION>/clusters/<YOUR_CLUSTER>/instances/<YOUR_INSTANCE>",
+            connect=getconn,
+        )
+
+        # acquire connection and query AlloyDB database
+        async with pool.acquire() as conn:
+            res = await conn.fetch("SELECT NOW()")
+```
+
+#### SQLAlchemy Async Engine
+
 ```python
 import asyncio
 import asyncpg
@@ -321,17 +390,17 @@ from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine
 from google.cloud.alloydb.connector import AsyncConnector
 
 async def init_connection_pool(connector: AsyncConnector) -> AsyncEngine:
-    # initialize Connector object for connections to AlloyDB
+    # creation function to generate asyncpg connections as 'async_creator' arg
     async def getconn() -> asyncpg.Connection:
-            conn: asyncpg.Connection = await connector.connect(
-                "projects/<YOUR_PROJECT>/locations/<YOUR_REGION>/clusters/<YOUR_CLUSTER>/instances/<YOUR_INSTANCE>",
-                "asyncpg",
-                user="my-user",
-                password="my-password",
-                db="my-db-name"
-                # ... additional database driver args
-            )
-            return conn
+        conn: asyncpg.Connection = await connector.connect(
+            "projects/<YOUR_PROJECT>/locations/<YOUR_REGION>/clusters/<YOUR_CLUSTER>/instances/<YOUR_INSTANCE>",
+            "asyncpg",
+            user="my-user",
+            password="my-password",
+            db="my-db-name"
+            # ... additional database driver args
+        )
+        return conn
 
     # The AlloyDB Python Connector can be used along with SQLAlchemy using the
     # 'async_creator' argument to 'create_async_engine'

setup.py

@@ -77,7 +77,7 @@
     install_requires=dependencies,
     extras_require={
         "pg8000": ["pg8000>=1.31.1"],
-        "asyncpg": ["asyncpg>=0.29.0"],
+        "asyncpg": ["asyncpg>=0.30.0"],
     },
     python_requires=">=3.9",
     include_package_data=True,

tests/system/test_asyncpg_connection.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import os
-from typing import Tuple
+from typing import Any, Tuple
 
 # [START alloydb_sqlalchemy_connect_async_connector]
 import asyncpg
@@ -88,7 +88,65 @@ async def getconn() -> asyncpg.Connection:
 # [END alloydb_sqlalchemy_connect_async_connector]
 
 
-async def test_connection_with_asyncpg() -> None:
+async def create_asyncpg_pool(
+    instance_connection_name: str,
+    user: str,
+    password: str,
+    db: str,
+    refresh_strategy: str = "background",
+) -> tuple[asyncpg.Pool, AsyncConnector]:
+    """Creates a native asyncpg connection pool for an AlloyDB instance and
+    returns the pool and the connector. Callers are responsible for closing the
+    pool and the connector.
+
+    A sample invocation looks like:
+
+        pool, connector = await create_asyncpg_pool(
+            inst_conn_name,
+            user,
+            password,
+            db,
+        )
+        async with pool.acquire() as conn:
+            hello = await conn.fetch("SELECT 'Hello World!'")
+            # do something with query result
+            await connector.close()
+
+    Args:
+        instance_connection_name (str):
+            The instance connection name specifies the instance relative to the
+            project and region. For example: "my-project:my-region:my-instance"
+        user (str):
+            The database user name, e.g., postgres
+        password (str):
+            The database user's password, e.g., secret-password
+        db (str):
+            The name of the database, e.g., mydb
+        refresh_strategy (Optional[str]):
+            Refresh strategy for the Cloud SQL Connector. Can be one of "lazy"
+            or "background". For serverless environments use "lazy" to avoid
+            errors resulting from CPU being throttled.
+    """
+    connector = AsyncConnector(refresh_strategy=refresh_strategy)
+
+    async def getconn(
+        instance_connection_name: str, **kwargs: Any
+    ) -> asyncpg.Connection:
+        conn: asyncpg.Connection = await connector.connect(
+            instance_connection_name,
+            "asyncpg",
+            user=user,
+            password=password,
+            db=db,
+        )
+        return conn
+
+    # create native asyncpg pool (requires asyncpg version >=0.30.0)
+    pool = await asyncpg.create_pool(instance_connection_name, connect=getconn)
+    return pool, connector
+
+
+async def test_sqlalchemy_connection_with_asyncpg() -> None:
     """Basic test to get time from database."""
     inst_uri = os.environ["ALLOYDB_INSTANCE_URI"]
     user = os.environ["ALLOYDB_USER"]
@@ -104,7 +162,7 @@ async def test_connection_with_asyncpg() -> None:
     await connector.close()
 
 
-async def test_lazy_connection_with_asyncpg() -> None:
+async def test_lazy_sqlalchemy_connection_with_asyncpg() -> None:
     """Basic test to get time from database."""
     inst_uri = os.environ["ALLOYDB_INSTANCE_URI"]
     user = os.environ["ALLOYDB_USER"]
@@ -120,3 +178,37 @@ async def test_lazy_connection_with_asyncpg() -> None:
         assert res[0] == 1
 
     await connector.close()
+
+
+async def test_connection_with_asyncpg() -> None:
+    """Basic test to get time from database."""
+    inst_uri = os.environ["ALLOYDB_INSTANCE_URI"]
+    user = os.environ["ALLOYDB_USER"]
+    password = os.environ["ALLOYDB_PASS"]
+    db = os.environ["ALLOYDB_DB"]
+
+    pool, connector = await create_asyncpg_pool(inst_uri, user, password, db)
+
+    async with pool.acquire() as conn:
+        res = await conn.fetch("SELECT 1")
+        assert res[0][0] == 1
+
+    await connector.close()
+
+
+async def test_lazy_connection_with_asyncpg() -> None:
+    """Basic test to get time from database."""
+    inst_uri = os.environ["ALLOYDB_INSTANCE_URI"]
+    user = os.environ["ALLOYDB_USER"]
+    password = os.environ["ALLOYDB_PASS"]
+    db = os.environ["ALLOYDB_DB"]
+
+    pool, connector = await create_asyncpg_pool(
+        inst_uri, user, password, db, "lazy"
+    )
+
+    async with pool.acquire() as conn:
+        res = await conn.fetch("SELECT 1")
+        assert res[0][0] == 1
+
+    await connector.close()