feat: use non-blocking disk read/writes (#1142)

Python's standard library read and writes are blocking IO.

This PR switches to use aiofiles which is asyncio native approach to
read/write to disk.

google/cloud/sql/connector/connection_info.py

@@ -17,9 +17,10 @@
 from dataclasses import dataclass
 import logging
 import ssl
-from tempfile import TemporaryDirectory
 from typing import Any, Dict, Optional, TYPE_CHECKING
 
+from aiofiles.tempfile import TemporaryDirectory
+
 from google.cloud.sql.connector.exceptions import CloudSQLIPTypeError
 from google.cloud.sql.connector.exceptions import TLSVersionError
 from google.cloud.sql.connector.utils import write_to_file
@@ -45,7 +46,7 @@ class ConnectionInfo:
     expiration: datetime.datetime
     context: Optional[ssl.SSLContext] = None
 
-    def create_ssl_context(self, enable_iam_auth: bool = False) -> ssl.SSLContext:
+    async def create_ssl_context(self, enable_iam_auth: bool = False) -> ssl.SSLContext:
         """Constructs a SSL/TLS context for the given connection info.
 
         Cache the SSL context to ensure we don't read from disk repeatedly when
@@ -83,8 +84,8 @@ def create_ssl_context(self, enable_iam_auth: bool = False) -> ssl.SSLContext:
         # tmpdir and its contents are automatically deleted after the CA cert
         # and ephemeral cert are loaded into the SSLcontext. The values
         # need to be written to files in order to be loaded by the SSLContext
-        with TemporaryDirectory() as tmpdir:
-            ca_filename, cert_filename, key_filename = write_to_file(
+        async with TemporaryDirectory() as tmpdir:
+            ca_filename, cert_filename, key_filename = await write_to_file(
                 tmpdir, self.server_ca_cert, self.client_cert, self.private_key
             )
             context.load_cert_chain(cert_filename, keyfile=key_filename)

google/cloud/sql/connector/connector.py

@@ -365,14 +365,14 @@ async def connect_async(
             if driver in ASYNC_DRIVERS:
                 return await connector(
                     ip_address,
-                    conn_info.create_ssl_context(enable_iam_auth),
+                    await conn_info.create_ssl_context(enable_iam_auth),
                     **kwargs,
                 )
             # synchronous drivers are blocking and run using executor
             connect_partial = partial(
                 connector,
                 ip_address,
-                conn_info.create_ssl_context(enable_iam_auth),
+                await conn_info.create_ssl_context(enable_iam_auth),
                 **kwargs,
             )
             return await self._loop.run_in_executor(None, connect_partial)

google/cloud/sql/connector/utils.py

@@ -13,8 +13,10 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+
 from typing import Tuple
 
+import aiofiles
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric import rsa
@@ -57,7 +59,7 @@ async def generate_keys() -> Tuple[bytes, str]:
     return priv_key, pub_key
 
 
-def write_to_file(
+async def write_to_file(
     dir_path: str, serverCaCert: str, ephemeralCert: str, priv_key: bytes
 ) -> Tuple[str, str, str]:
     """
@@ -68,12 +70,12 @@ def write_to_file(
     cert_filename = f"{dir_path}/cert.pem"
     key_filename = f"{dir_path}/priv.pem"
 
-    with open(ca_filename, "w+") as ca_out:
-        ca_out.write(serverCaCert)
-    with open(cert_filename, "w+") as ephemeral_out:
-        ephemeral_out.write(ephemeralCert)
-    with open(key_filename, "wb") as priv_out:
-        priv_out.write(priv_key)
+    async with aiofiles.open(ca_filename, "w+") as ca_out:
+        await ca_out.write(serverCaCert)
+    async with aiofiles.open(cert_filename, "w+") as ephemeral_out:
+        await ephemeral_out.write(ephemeralCert)
+    async with aiofiles.open(key_filename, "wb") as priv_out:
+        await priv_out.write(priv_key)
 
     return (ca_filename, cert_filename, key_filename)
 

requirements.txt

@@ -1,3 +1,4 @@
+aiofiles==24.1.0
 aiohttp==3.9.5
 cryptography==42.0.8
 Requests==2.32.3

setup.py

@@ -25,6 +25,7 @@
 )
 release_status = "Development Status :: 5 - Production/Stable"
 dependencies = [
+    "aiofiles",
     "aiohttp",
     "cryptography>=42.0.0",
     "Requests",

tests/unit/mocks.py

@@ -19,9 +19,9 @@
 import datetime
 import json
 import ssl
-from tempfile import TemporaryDirectory
 from typing import Any, Callable, Dict, Literal, Optional, Tuple
 
+from aiofiles.tempfile import TemporaryDirectory
 from aiohttp import web
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
@@ -203,8 +203,8 @@ async def create_ssl_context() -> ssl.SSLContext:
     # build default ssl.SSLContext
     context = ssl.create_default_context()
     # load ssl.SSLContext with certs
-    with TemporaryDirectory() as tmpdir:
-        ca_filename, cert_filename, key_filename = write_to_file(
+    async with TemporaryDirectory() as tmpdir:
+        ca_filename, cert_filename, key_filename = await write_to_file(
             tmpdir, server_ca_cert, ephemeral_cert, client_private
         )
         context.load_cert_chain(cert_filename, keyfile=key_filename)

tests/unit/test_instance.py

@@ -367,14 +367,14 @@ async def test_AutoIAMAuthNotSupportedError(fake_client: CloudSQLClient) -> None
         await cache._current
 
 
-def test_ConnectionInfo_caches_sslcontext() -> None:
+async def test_ConnectionInfo_caches_sslcontext() -> None:
     info = ConnectionInfo(
         "cert", "cert", "key".encode(), {}, "POSTGRES", datetime.datetime.now()
     )
     # context should default to None
     assert info.context is None
     # cache a 'context'
     info.context = "context"
-    # caling create_ssl_context should no-op with an existing 'context'
-    info.create_ssl_context()
+    # calling create_ssl_context should no-op with an existing 'context'
+    await info.create_ssl_context()
     assert info.context == "context"