add utility to inject hostname into localhost URLs for node18 compat

README.md

@@ -208,7 +208,7 @@ custom:
 
 ## Change Log
 
-* v1.1.2: Unify construction of target endpoint URL, add support for configuring `$AWS_ENDPOINT_URL`
+* v1.1.2: Unify construction of target endpoint URL, add support for configuring `AWS_ENDPOINT_URL`
 * v1.1.1: Fix layer deployment if `mountCode` is enabled by always packaging and deploying
 * v1.1.0: Fix SSM environment variables resolving issues with serverless v3, change default for `BUCKET_MARKER_LOCAL` to `hot-reload`
 * v1.0.6: Add `BUCKET_MARKER_LOCAL` configuration for customizing S3 bucket for lambda mount and [Hot Reloading](https://docs.localstack.cloud/user-guide/tools/lambda-tools/hot-reloading/).

src/index.js

@@ -759,19 +759,34 @@ class LocalstackPlugin {
 
   getServiceURL(hostname) {
     if (process.env.AWS_ENDPOINT_URL) {
-      return process.env.AWS_ENDPOINT_URL;
+      return injectHostnameIntoLocalhostURL(process.env.AWS_ENDPOINT_URL, hostname);
     }
     hostname = hostname || 'localhost';
     const proto = TRUE_VALUES.includes(process.env.USE_SSL) ? 'https' : 'http';
     const port = this.getEdgePort();
-    if (proto === 'https' && `${port}` === '443') {
-      // little hack here - required to remove the default HTTPS port 443, as otherwise
-      // routing for some platforms and ephemeral instances (e.g., on namespace.so) fails
+    // little hack here - required to remove the default HTTPS port 443, as otherwise
+    // routing for some platforms and ephemeral instances (e.g., on namespace.so) fails
+    const isDefaultPort =
+      (proto === 'http' && `${port}` === '80') ||
+      (proto === 'https' && `${port}` === '443');
+    if (isDefaultPort) {
       return `${proto}://${hostname}`;
     }
     return `${proto}://${hostname}:${port}`;
   }
 
+  /**
+   * If the given `endpointURL` points to `localhost`, then inject the given `hostname` into the URL
+   * and return it. This helps fix IPv6 issues with node v18+ (see also getConnectHostname() above)
+   */
+  injectHostnameIntoLocalhostURL(endpointURL, hostname) {
+    const url = new URL(endpointURL);
+    if (hostname && url.hostname === 'localhost') {
+      url.hostname = hostname;
+    }
+    return url.href;
+  }
+
   log(msg) {
     if (this.serverless.cli) {
       this.serverless.cli.log.call(this.serverless.cli, msg);