SSR

Server-side rendering with the v3 Angular adapter — the ssr builder flag, what the schematic rewrites, and how initNodeFederation resolves shared dependencies in Node.

Native Federation v3 supports server-side rendering through a second package, @softarc/native-federation-node. It applies the same import map the browser gets, but as a Node module resolver hook, so a server bundle resolves @angular/core to the same file the browser would.

Enabling SSR

Add SSR to the project the normal Angular way first, then run the adapter's init schematic:

ng add @angular/ssr --project shell
ng g @angular-architects/native-federation:init --project shell --port 4200 --type dynamic-host

The schematic detects SSR by looking for an ssr option on the project's build target. When it finds one it:

• adds cors to package.json (the server has to allow the remotes' origins);
• sets ssr: true on the federation build target in angular.json;
• rewrites the server entry point, moving the original content to bootstrap-server.ts.

@softarc/native-federation-node is added to package.json by the schematic in every case, SSR or not.

What the schematic writes

The server entry becomes a small launcher that initializes federation before importing the real server:

// projects/shell/src/server.ts (generated, dynamic-host)
import { initNodeFederation } from '@softarc/native-federation-node';

console.log('Starting SSR for Shell');

(async () => {
  await initNodeFederation({
    remotesOrManifestUrl: '../browser/federation.manifest.json',
    relBundlePath: '../browser/',
  });

  await import('./bootstrap-server');
})();

For --type host the manifest path is replaced by the inlined remote map; for a remote, only relBundlePath is passed. The ordering requirement is the same as in the browser: the resolver has to be registered before any module that imports a shared package is evaluated, which is what the dynamic import('./bootstrap-server') guarantees.

bootstrap-server.ts is the original server file with three edits: cors is required through createRequire and applied to the Express app, the view engine is set to html, and the isMainModule(import.meta.url) guard is unwrapped so the server starts on import rather than only when run directly.

What initNodeFederation does

type InitNodeFederationOptions = {
  remotesOrManifestUrl: Record<string, string> | string;  // default {}
  relBundlePath: string;                                  // default '../browser'
  throwIfRemoteNotFound: boolean;                         // default false
  cacheTag?: string;
};

1. Reads the host's remoteEntry.json from <relBundlePath>/remoteEntry.json off the file system — not over HTTP — and turns it into root import-map entries prefixed with relBundlePath.
2. Loads the remotes. A string remotesOrManifestUrl is read as a local file, not fetched; an object is used as-is. Each remote's remoteEntry.json is then fetched over the network exactly as in the browser, so remote origins must be reachable from the server.
3. Merges both maps and writes them to node.importmap in the process's working directory.
4. Writes federation-resolver.mjs next to it and registers it with module.register().

From that point on, Node resolves bare specifiers through the generated map. The resolver reads node.importmap from the working directory; set IMPORT_MAP_PATH to point it elsewhere.

The ssr builder flag

ssr: true on the federation build target changes two things:

• The externals are handed to Angular as externalDependencies instead of through the esbuild externals plugin — the server build fails if they are supplied as plugin options.
• A launcher script, fstart.mjs, is written to dist/<project>/server/.

The flag is ignored while dev is on, so ng serve renders without federated SSR; the dev server still serves the browser artifacts as usual.

fstart.mjs

The generated launcher is an alternative to editing the server entry yourself. It calls initNodeFederation and then imports your server bundle:

cd dist/shell/server
node fstart.mjs --entry ./server.mjs --relBundlePath ../browser/ \
                --remotesOrManifestUrl ../browser/federation.manifest.json

Unknown switches or stray values print the usage and exit.

Limits on v3

Remote modules execute on the server through the resolver hook, but everything else about the v3 runtime applies: deduplication is exact-version only, there is no persistent cache, and the manifest is read once at startup. Nothing re-reads it while the server runs, so a redeployed remote needs a server restart.

Related

• Builder — where the ssr flag lives.
• Runtime → API Reference — processHostInfo, processRemoteInfos and mergeImportMaps, which initNodeFederation composes.
• SSR & Hydration — the general picture.