### Understand the alert

This alert triggers when the rate of rate-limited RPC (Remote Procedure Call) requests made by a Consul server within the specified datacenter has exceeded a certain threshold. If you receive this alert, it means that your Consul server is experiencing an increased number of rate-limited RPC requests, which may affect its performance and availability.

### What is Consul?

Consul is a service mesh solution used for service discovery, configuration, and segmentation. It provides a distributed platform to build robust, scalable, and secured services while simplifying network infrastructure.

### What are RPC requests?

Remote Procedure Call (RPC) is a protocol that allows a computer to execute a procedure on another computer across a network. In the context of Consul, RPC requests are used for communication between Consul servers and clients.

### Troubleshoot the alert

1. Check the Consul server logs for any relevant error messages or warnings. These logs can provide valuable information on the cause of the increased RPC requests.

   ```
   journalctl -u consul
   ```

2. Monitor the Consul server's resource usage, such as CPU and memory utilization, to ensure that it is not running out of resources. High resource usage may cause an increase in rate-limited RPC requests.

   ```
   top -o +%CPU
   ```

3. Analyze the Consul client's usage patterns and identify any misconfigured services or clients contributing to the increased RPC requests. Identify any services that may be sending a high number of requests per second or are not appropriately rate-limited.

4. Review the Consul rate-limiting configurations to ensure that they are set appropriately based on the expected workload. Adjust the rate limits if necessary to better accommodate the workload.

5. If the issue persists, consider scaling up the Consul server resources or deploying more Consul servers to handle increased traffic and prevent performance issues.

### Useful resources

1. [Consul Official Documentation](https://www.consul.io/docs/)
2. [Consul Rate Limiting Guide](https://developer.hashicorp.com/consul/docs/agent/limits)
3. [Understanding Remote Procedure Calls (RPC)](https://www.smashingmagazine.com/2016/09/understanding-rest-and-rpc-for-http-apis/)
4. [Troubleshooting Consul](https://developer.hashicorp.com/consul/tutorials/datacenter-operations/troubleshooting)
