@smithy/middleware-endpoint

Custom Endpoint Resolution

This feature allows you to customize the endpoint resolution logic. In this example, the middleware modifies the request's hostname to a custom endpoint before passing it to the next middleware in the stack.

const { EndpointMiddleware } = require('@smithy/middleware-endpoint');
const { HttpRequest } = require('@smithy/protocol-http');

const customEndpointMiddleware = (next, context) => async (args) => {
  const request = args.request;
  if (HttpRequest.isInstance(request)) {
    request.hostname = 'custom-endpoint.example.com';
  }
  return next({ ...args, request });
};

// Usage in a client configuration
const client = new SomeAWSClient({
  region: 'us-west-2',
  middlewareStack: [customEndpointMiddleware]
});

Conditional Endpoint Resolution

This feature allows you to conditionally resolve endpoints based on the operation being performed. In this example, the middleware changes the endpoint only for the 'GetItem' operation.

const { EndpointMiddleware } = require('@smithy/middleware-endpoint');
const { HttpRequest } = require('@smithy/protocol-http');

const conditionalEndpointMiddleware = (next, context) => async (args) => {
  const request = args.request;
  if (HttpRequest.isInstance(request) && context.operationName === 'GetItem') {
    request.hostname = 'get-item-endpoint.example.com';
  }
  return next({ ...args, request });
};

// Usage in a client configuration
const client = new SomeAWSClient({
  region: 'us-west-2',
  middlewareStack: [conditionalEndpointMiddleware]
});