What purpose do Envoy filters serve?

Envoy filters serve the critical function of processing requests and responses that pass through the proxy. This capability allows Envoy to intercept and manipulate these data packets at various stages, enabling a multitude of functionalities such as logging, authentication, routing, and modifying headers or payloads.

Filters are a powerful feature that gives developers and operators the ability to implement custom behavior within the data path without requiring any changes to the core Envoy proxy itself. For instance, one might use filters to implement security protocols, add tracing information, or even perform transformations on the request and response bodies. This flexibility makes filters integral to deploying microservices architectures, as they allow for nuanced control over how each service interacts with one another.

The other options, while they describe important capabilities of a proxy in general, do not accurately depict the specific purpose of Envoy filters. Terminating connections, load balancing, and encrypting data are functionalities that may involve the use of filters, but they do not define what filters are primarily designed to accomplish within the Envoy architecture. Filters are not limited to these tasks but are versatile tools tailored for request and response processing.