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server.cors

  • Type: boolean | import('cors').CorsOptions
const defaultAllowedOrigins =
  /^https?:\/\/(?:(?:[^:]+\.)?localhost|127\.0\.0\.1|\[::1\])(?::\d+)?$/;

const defaultOptions = {
  // Default allowed:
  // - localhost
  // - 127.0.0.1
  // - [::1]
  origin: defaultAllowedOrigins,
};
  • Version: >= 1.1.11

Configure CORS options for the dev server or preview server, based on the cors middleware.

  • object：Enable CORS with the specified options.
  • true：Enable CORS with default options (allow all origins, not recommended).
  • false：Disable CORS.
WARNING

Using cors: true or cors.origin: '*' exposes your dev server to all origins, potentially compromising your source code security. It is recommended to use origin option to specify an allowlist of trusted origins instead.

Example

  • Enable CORS for a specific origin:
rsbuild.config.ts
export default {
  server: {
    cors: {
      // Configures the `Access-Control-Allow-Origin` CORS response header
      origin: 'https://example.com',
    },
  },
};
  • Keep the default origin config of Rsbuild and add additional origins:
rsbuild.config.ts
// `defaultAllowedOrigins` is the default origin value of Rsbuild
import { defaultAllowedOrigins } from '@rsbuild/core';

export default {
  server: {
    cors: {
      origin: [defaultAllowedOrigins, 'https://example.com'],
    },
  },
};
  • Only enable CORS for the dev server:
rsbuild.config.ts
const isDev = process.env.NODE_ENV === 'development';

export default {
  server: {
    cors: isDev ? { origin: 'https://example.com' } : false,
  },
};
  • Disable CORS:
rsbuild.config.ts
export default {
  server: {
    cors: false,
  },
};
  • Enable CORS for all origins (not recommended):
rsbuild.config.ts
export default {
  server: {
    // Equivalent to `{ origin: '*' }`
    cors: true,
  },
};

Options

The cors option can be an object, which is the same as the cors middleware options.

The default configuration is the equivalent of:

const defaultOptions = {
  origin: '*',
  methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
  preflightContinue: false,
  optionsSuccessStatus: 204,
};

origin

  • Type:
type StaticOrigin =
  | boolean
  | string
  | RegExp
  | Array<boolean | string | RegExp>;

type CustomOrigin = (
  requestOrigin: string | undefined,
  callback: (err: Error | null, origin?: StaticOrigin) => void,
) => void;

type Origin = StaticOrigin | CustomOrigin;

The origin option is used to configure the Access-Control-Allow-Origin header:

rsbuild.config.ts
export default {
  server: {
    cors: {
      origin: 'https://example.com',
    },
  },
};

Specify multiple allowed origins using an array:

rsbuild.config.ts
export default {
  server: {
    cors: {
      origin: [
        /^https?:\/\/(?:(?:[^:]+\.)?localhost|127\.0\.0\.1|\[::1\])(?::\d+)?$/,
        'https://example.com',
      ],
    },
  },
};

Use a regular expression to allow all matching origins:

rsbuild.config.ts
export default {
  server: {
    cors: {
      origin: /\.example\.com$/,
    },
  },
};

Setting origin to a function allows you to dynamically determine the allowed origin, the function receives two parameters:

  • origin：The origin of the incoming request, undefined if no origin is present.
  • callback：A function to set the allowed origin.
rsbuild.config.ts
export default {
  server: {
    cors: {
      origin: (origin, callback) => {
        // loadMyOrigins is an example call to load a list of origins
        loadMyOrigins((error, origins) => {
          callback(error, origins);
        });
      },
    },
  },
};