feat(options): added options for follow redirects with max body length and max redirects

src/configuration.ts

@@ -5,4 +5,14 @@ export function verifyConfig<TReq, TRes>(options: Options<TReq, TRes>): void {
   if (!options.target && !options.router) {
     throw new Error(ERRORS.ERR_CONFIG_FACTORY_TARGET_MISSING);
   }
+  if (options.followRedirects && options.followRedirectsOpts) {
+    if (
+      (options.followRedirectsOpts.maxRedirects !== undefined &&
+        options.followRedirectsOpts.maxRedirects <= 0) ||
+      (options.followRedirectsOpts.maxBodyLength !== undefined &&
+        options.followRedirectsOpts.maxBodyLength <= 0)
+    ) {
+      throw new Error(ERRORS.ERR_FOLLOW_REDIRECT_INVALID_OPTIONS);
+    }
+  }
 }

src/errors.ts

@@ -3,4 +3,5 @@ export enum ERRORS {
   ERR_CONTEXT_MATCHER_GENERIC = '[HPM] Invalid context. Expecting something like: "/api" or ["/api", "/ajax"]',
   ERR_CONTEXT_MATCHER_INVALID_ARRAY = '[HPM] Invalid pathFilter. Expecting something like: ["/api", "/ajax"] or ["/api/**", "!**.html"]',
   ERR_PATH_REWRITER_CONFIG = '[HPM] Invalid pathRewrite config. Expecting object with pathRewrite config or a rewrite function',
+  ERR_FOLLOW_REDIRECT_INVALID_OPTIONS = '[HPM] Invalid followRedirectsOpts config',
 }

src/http-proxy-middleware.ts

@@ -29,6 +29,8 @@ export class HttpProxyMiddleware<TReq, TRes> {
 
     this.pathRewriter = PathRewriter.createPathRewriter(this.proxyOptions.pathRewrite); // returns undefined when "pathRewrite" is not provided
 
+    this.setFollowRedirectsOptions(options);
+
     // https://github.com/chimurai/http-proxy-middleware/issues/19
     // expose function to upgrade externally
     this.middleware.upgrade = (req, socket, head) => {
@@ -84,6 +86,30 @@ export class HttpProxyMiddleware<TReq, TRes> {
     });
   }
 
+  /**
+   Sets follow-redirects module global options used internally by http-proxy. When followRedirects is true, http-proxy uses the http and https agents of the follow-redirects module https://github.com/http-party/node-http-proxy/blob/9b96cd725127a024dabebec6c7ea8c807272223d/lib/http-proxy/passes/web-incoming.js#L105
+  */
+  private setFollowRedirectsOptions = (options: Options<TReq, TRes>) => {
+    if (!options.followRedirectsOpts) {
+      return;
+    }
+    // eslint-disable-next-line @typescript-eslint/no-var-requires
+    const followRedirects = require('follow-redirects'); // Since there is no way to access the module from http-proxy and also given that http-proxy is unmaintained.
+    if (!followRedirects) {
+      return;
+    }
+    // Sets follow-redirects global options according to https://github.com/follow-redirects/follow-redirects?tab=readme-ov-file#global-options
+    // This is a workaround, the options are set globally, ideally follow redirect options should be set through the http-proxy.
+    if (options.followRedirectsOpts.maxRedirects) {
+      followRedirects.maxRedirects = options.followRedirectsOpts.maxRedirects;
+      debug('set followRedirects.maxRedirects globally', followRedirects.maxRedirects);
+    }
+    if (options.followRedirectsOpts.maxBodyLength) {
+      followRedirects.maxBodyLength = options.followRedirectsOpts.maxBodyLength;
+      debug('set followRedirects.maxBodyLength globally', followRedirects.maxBodyLength);
+    }
+  };
+
   private catchUpgradeRequest = (server: https.Server) => {
     if (!this.wsInternalSubscribed) {
       debug('subscribing to server upgrade event');

src/types.ts

@@ -139,4 +139,15 @@ export interface Options<TReq = http.IncomingMessage, TRes = http.ServerResponse
    * @since v3.0.0
    */
   logger?: Logger | any;
+
+  /**
+   * Configures options for follow-redirects when followRedirects is true.
+   * @property {number} [maxRedirects] - The maximum number of redirects to follow.
+   * @property {number} [maxBodyLength] - The maximum allowed size of the response body in bytes.
+   * @see {@link https://github.com/follow-redirects/follow-redirects?tab=readme-ov-file#global-options}
+   */
+  followRedirectsOpts?: {
+    maxRedirects?: number;
+    maxBodyLength?: number;
+  };
 }