Envoy is an open-source edge and service proxy designed for cloud-native applications. It is used to manage network traffic, providing features like load balancing, service discovery, and observability. Envoy is often deployed as a sidecar in service mesh architectures, enhancing the communication between microservices.
When using Envoy, you might encounter a situation where requests are being delayed or dropped. This is often accompanied by error messages indicating that the upstream server is overloaded. This symptom suggests that the server handling the requests cannot process the incoming load efficiently.
The root cause of an overloaded upstream server is typically due to insufficient resources to handle the volume of requests. This can occur because of increased traffic, inefficient resource allocation, or suboptimal server performance. Envoy, acting as a proxy, can only forward requests as fast as the upstream server can handle them.
To address the issue of an overloaded upstream server, consider the following steps:
One of the most effective solutions is to scale the upstream server horizontally or vertically:
Improving the performance of the upstream server can help it handle more requests efficiently:
To prevent overwhelming the upstream server, implement rate limiting at the Envoy level. This can be configured in Envoy's configuration file:
rate_limits:
- stage: 0
actions:
- type: "request_headers"
header_name: "x-user-id"
For detailed configuration options, refer to the Envoy Rate Limit Filter documentation.
By scaling the upstream server, optimizing its performance, and implementing rate limiting, you can effectively manage and resolve the issue of an overloaded upstream server in Envoy. Regular monitoring and proactive resource management are key to maintaining a robust and responsive service architecture.
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