Скачать или смотреть How to Resolve cloud-sql-proxy Connection Issues with mysql on GCP

Discover how to fix connection failures between `cloud-sql-proxy` and `mysql` when working with Google Cloud SQL.
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Troubleshooting cloud-sql-proxy Connection Issues with MySQL on Google Cloud SQL

Connecting to a Google Cloud SQL instance can be seamless with the help of cloud-sql-proxy, but sometimes you may encounter roadblocks. One common issue arises when the mysql client seems unable to connect, while other methods like telnet work perfectly. In this post, we will explore the reasons behind this issue and provide you with a clear solution.

The Problem

A user has reported difficulty connecting to their GCP Cloud SQL instance using the mysql client, despite successfully starting the cloud-sql-proxy. The proxy appears to be running correctly, as it listens on the expected host and port, but attempts to connect using the mysql client fail with the following error:

[[See Video to Reveal this Text or Code Snippet]]

Interestingly, the user found that connecting via telnet to the same address worked without any issues, leading to confusion.

Understanding the Connection Mechanics

The key to solving this problem lies in understanding how Docker handles network connections. In this particular case, the user was utilizing a Docker container to run the mysql client, which altered the way network connections were processed.

Docker Networking Basics

By default, Docker containers run in isolation and have their own virtual network interface. When a user specifies 127.0.0.1 to connect to the MySQL server, the request is routed to the local interface of the container rather than to the host machine where the cloud-sql-proxy is running.

The Solution

To resolve the connection issue, a simple adjustment to the Docker run command can make all the difference:

Initial Setup: Initially, the user was running the mysql client using the following script:

[[See Video to Reveal this Text or Code Snippet]]

Identifying the Issue: Since the cloud-sql-proxy listens on 127.0.0.1 of the host machine, the command needs to route this request correctly. By default, Docker was trying to connect to the 127.0.0.1 of the container itself.

Adjusting the Docker Command: To fix this, adding the --network=host flag to the Docker run command allows the container to access the host's network directly:

[[See Video to Reveal this Text or Code Snippet]]

By using --network=host, the mysql command still specifies -h 127.0.0.1, but this time it connects to the host's network interface where the cloud-sql-proxy is running successfully.

Conclusion

Network misrouting caused the initial confusion when trying to connect to a Google Cloud SQL instance using mysql via Docker. By adjusting the way Docker interacts with the host network, the user was able to establish the desired connections seamlessly.

If you ever find yourself dealing with similar connection issues, consider the networking setup of your container and how it interacts with your local machine.

Additional Tips

Always verify which binaries are being used in scripts, as wrappers to Docker can lead to unexpected behavior.

Consult Docker documentation for more insights on networking modes, as choosing the correct mode can simplify many network-related problems.

By following this guide, you should be able to overcome similar connection woes and ensure that your workflow remains uninterrupted.