Is there a way to enforce a limit on batch requests in Apollo Server?

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Summary

The problem revolves around enforcing a limit on batch requests in Apollo Server, which by default has batch requests disabled. To tackle this, we need to understand how Apollo Server handles batch requests and where we can intervene to set a limit.

Root Cause

The root cause of the issue is that Apollo Server does not provide direct access to the original batch query in the GraphQLRequestContext when using requestDidStart. This makes it challenging to determine the size or length of the batch request directly. Key points include:

  • Apollo Server’s default behavior of disabling batch requests
  • The lack of direct access to the original batch query in GraphQLRequestContext
  • The need for an alternative approach to enforce batch request limits

Why This Happens in Real Systems

This issue arises in real systems because of the way Apollo Server is designed to handle GraphQL requests. By default, it disables batch requests for security and performance reasons. However, when batch requests are enabled, the server processes each request individually, making it difficult to access the batch query as a whole. Reasons include:

  • Security concerns related to batch requests
  • Performance optimization by processing requests individually
  • Design limitations in accessing batch query information

Real-World Impact

The real-world impact of not being able to enforce a limit on batch requests includes:

  • Security vulnerabilities due to potential abuse of batch requests
  • Performance issues if a large number of requests are batched together
  • Difficulty in debugging and managing batch requests without limits

Example or Code

const { ApolloServer } = require('apollo-server');

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req, res }) => ({ req, res }),
  subscriptions: {
    onConnect: (connectionParams, webSocket, context) => {
      // Potential point for custom logic
    },
  },
  // Potential custom middleware or plugins for batch request handling
});

server.listen().then(({ url }) => {
  console.log(`Server ready at ${url}`);
});

How Senior Engineers Fix It

Senior engineers fix this issue by implementing custom middleware or plugins that can intercept and analyze batch requests before they are processed by Apollo Server. This can involve:

  • Parsing the request body to determine the batch query size
  • Implementing rate limiting or request size limits
  • Using external libraries or tools designed for GraphQL batch request management

Why Juniors Miss It

Junior engineers might miss this solution because they:

  • Lack experience with custom middleware and plugin development for Apollo Server
  • Are not familiar with the security and performance implications of batch requests
  • Overlook the need for manual parsing and analysis of request bodies to enforce limits

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