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feat: reset connection when the DNS record changes #1241

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Merged
merged 18 commits into from
Mar 21, 2025
Merged

feat: reset connection when the DNS record changes #1241

merged 18 commits into from
Mar 21, 2025

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jackwotherspoon
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@jackwotherspoon jackwotherspoon commented Mar 3, 2025 •
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If the connector is configured with a domain name, when that domain name record changes to
resolve to a new instance, the connector should detect that change, close all connections to the old
instance, and create connections to the new instance.

import sqlalchemy
from google.cloud.sql.connector import Connector, DnsResolver

# using default failover period of 30 seconds
connector = Connector(resolver=DnsResolver)

# using custom failover period
# connector = Connector(resolver=DnsResolver, failover_period=60)

# establish connection using domain name
engine = sqlalchemy.create_engine(
    "postgresql+pg8000://",
    creator=lambda: connector.connect(
        "db.example.com",
        "pg8000",
        user="my-user",
        password="my-password",
        db="my-db",
        ip_type="public",  # can also be "private" or "psc"
    ),
)
with engine.connect() as conn:
      curr_time = conn.execute(sqlalchemy.text("SELECT NOW()")).fetchone()
      conn.commit()

If db.example.com fails over from my-project:us-central1:pg to my-project:us-central1:pg-replica then the connections will be closed and re-opened to new instance.

2025-03-20 14:07:05,504 [DEBUG]: ['db.example.com -> my-project:us-central1:pg']: Connecting to 34.172.89.123:3307
2025-03-20 14:07:16,137 [DEBUG]: ['db.example.com -> my-project:us-central1:pg-replica']: Connecting to 34.60.127.180:3307
2025-03-20 14:07:19,387 [DEBUG]: ['db.example.com -> my-project:us-central1:pg']: Cloud SQL instance changed from my-project:us-central1:pg to my-project:us-central1:pg-replica, closing all connections!
2025-03-20 14:07:19,387 [DEBUG]: ['db.example.com -> my-project:us-central1:pg']: Cancelled domain name polling task.
2025-03-20 14:07:19,387 [DEBUG]: ['db.example.com -> my-project:us-central1:pg']: Canceling connection info refresh operation tasks
2025-03-20 14:07:19,387 [DEBUG]: ['db.example.com -> my-project:us-central1:pg']: Scheduled refresh operation cancelled
2025-03-20 14:07:21,472 [DEBUG]: ['db.example.com -> my-project:us-central1:pg-replica']: Connecting to 34.60.127.180:3307

Closes #1169

@jackwotherspoon jackwotherspoon self-assigned this Mar 3, 2025
jackwotherspoon
jackwotherspoon commented Mar 3, 2025
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google/cloud/sql/connector/connection_name.py
Comment on lines +41 to +44
def get_connection_string(self) -> str:
"""Get the instance connection string for the Cloud SQL instance."""
return f"{self.project}:{self.region}:{self.instance_name}"

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This allows for a reliable way to get the instance connection name for a Cloud SQL instance whether the connector is connecting via domain name or instance connection name.

jackwotherspoon
jackwotherspoon commented Mar 20, 2025
View reviewed changes
google/cloud/sql/connector/connector.py

conn_name = await self._resolver.resolve(instance_connection_string)
if (str(conn_name), enable_iam_auth) in self._cache:
monitored_cache = self._cache[(str(conn_name), enable_iam_auth)]
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Update cache key to be str(conn_name) which will result in cache key either being :

domain name -> instance connection name or just instance connection name

@jackwotherspoon jackwotherspoon marked this pull request as ready for review March 20, 2025 15:24
@jackwotherspoon jackwotherspoon requested a review from a team as a code owner March 20, 2025 15:24
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Example of failover working:

2025-03-20 14:07:05,504 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg']: Connecting to 34.172.89.123:3307
2025-03-20 14:07:16,137 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg-replica']: Connecting to 34.60.127.180:3307
2025-03-20 14:07:19,387 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg']: Cloud SQL instance changed from my-project:us-central1:pg to my-project:us-central1:pg-replica, closing all connections!
2025-03-20 14:07:19,387 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg']: Cancelled domain name polling task.
2025-03-20 14:07:19,387 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg']: Canceling connection info refresh operation tasks
2025-03-20 14:07:19,387 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg']: Scheduled refresh operation cancelled
2025-03-20 14:07:21,472 [DEBUG]: ['prod-db.mycompany.example.com -> my-project:us-central1:pg-replica']: Connecting to 34.60.127.180:3307

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Code coverage drop from 94% to 93% is negligible

hessjcg
hessjcg reviewed Mar 20, 2025
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@jackwotherspoon jackwotherspoon requested a review from hessjcg March 20, 2025 20:10
hessjcg
hessjcg reviewed Mar 21, 2025
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@jackwotherspoon jackwotherspoon merged commit 1405f56 into main Mar 21, 2025
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@jackwotherspoon jackwotherspoon deleted the dns-reset-connection branch March 21, 2025 16:40
@release-please release-please bot mentioned this pull request Mar 20, 2025
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Automatically configure and fail-over connections using DNS
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