Apollo Server Query Complexity Plugin

The `apollo-server-plugin-query-complexity` package provides a plugin for `@apollo/server` to enforce query complexity limits, safeguarding against overly resource-intensive queries. It is currently at version 4.0.0, aligning with `@apollo/server` v4.x. This plugin differentiates itself by being fully compatible with GraphQL operation variables, a feature that standard `graphql-js` validation rules cannot directly access when integrated with Apollo Server. It leverages `graphql-query-complexity` for its core estimation logic, supporting various estimators like `directiveEstimator` and `simpleEstimator`, which allow developers to define complexity values directly within their schema or through default calculation rules. This mechanism is crucial for preventing denial-of-service attacks by ensuring server stability and fair resource allocation. The project appears actively maintained, with releases typically synchronized with major `@apollo/server` versions.