What configuration language does Envoy utilize?

Envoy utilizes YAML as its configuration language because YAML is designed to be human-readable and easy to write, making it particularly suitable for configurations. It allows for a clean and hierarchical structure, which is very helpful for defining complex configurations like those used in Envoy to manage services, routing, listeners, clusters, and more.

The syntax of YAML increases clarity and minimizes the chances of errors during configuration, which is essential when dealing with intricate systems like service proxies. Additionally, YAML supports advanced data structures like lists and dictionaries, which are often necessary for nuanced configurations. Thus, using YAML allows developers to maintain their configurations more intuitively.

Other choices like XML and JSON also serve as configuration formats but may not provide the same level of ease in readability and editing. HTML, being primarily a markup language for web content, is not suitable for configuration purposes.