how to solve error SQL state 08S01?

Posted on January 22, 2020

Trying to work with kubernetes cluster and external mysql, but an error 08S01 connection failure raises when sending a request from a client. This rest service work correctly when working in a VPS without kubernetes, so, my guess is that there is a problem configuring kubernetes and mysql Any help will be appreciated

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Bobby

May 28, 2023

Hi there,

The SQL state error 08S01 corresponds to “Communication Link Failure”, and typically indicates an issue with the network connection to your MySQL server. When you’re deploying applications on a Kubernetes cluster, there are several common sources for this error:

Network Policy: Kubernetes network policies can prevent pods from communicating with each other or with external services. Make sure that your application’s pods have the necessary network policies to access your MySQL server.
Service Discovery: Are you correctly resolving the MySQL server’s address from within your Kubernetes cluster? You can test this by executing a nslookup or dig command from within one of your pods.
Firewall Rules: If your MySQL server is outside of your Kubernetes cluster, make sure that the server’s firewall allows incoming connections from the IP addresses of your Kubernetes nodes.
MySQL Server Configuration: The MySQL server must be configured to accept connections from the IP addresses of your Kubernetes nodes. Check the bind-address configuration in your MySQL server settings. If it’s set to 127.0.0.1 (the default in many cases), it will only accept connections from the same machine. Change it to 0.0.0.0 to accept connections from any IP, or list the specific IPs allowed to connect.
Incorrect Connection Parameters: Double-check your MySQL hostname, port, username, password, and database name to ensure they’re correct.

You can debug further by trying to establish a connection from within one of your Kubernetes pods directly using the mysql client, using the same parameters as your application:

kubectl exec -it [your-pod-name] -- /bin/bash mysql -h [your-mysql-hostname] -P [your-mysql-port] -u [your-mysql-username] -p

If you are able to connect, it means the problem likely lies within your application’s configuration or code. If not, the issue is more likely with your Kubernetes or MySQL server configuration.

Best,

Bobby