Build fails on Docker with app initializer that does http request

[k-schneider]

Command

build

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

I have an Angular v19 app that is failing within a docker build due to prerendering (even though I don't have any prerendered routes). The build succeeds when ran directly on my Windows workstation.

Minimal Reproduction

I have a really simple app configuration service/provider that exposes environment variables to the client:

export const provideAppConfig = () =>
  provideAppInitializer(() => appConfigInitializer(inject(AppConfigService)));

function appConfigInitializer(appConfigService: AppConfigService) {
  return appConfigService.load();
}

@Injectable({
  providedIn: "root",
})
export class AppConfigService {
  private http = inject(HttpClient);
  value = signal<AppConfig>({});

  public async load(): Promise<void> {
    const config = await firstValueFrom(
      this.http.get<AppConfig>("/app-config"),
    );
    this.value.set(config);
  }

  public get(key: string): any {
    return this.value()[key];
  }
}

interface AppConfig {
  [key: string]: any;
}

And an express route that serves back json:

const route = Router();

/**
 * Returns any public environment variables that start with PUBLIC_NG_ for use in the Angular app
 */
route.get("/app-config", (req, res) => {
  const config: Record<string, any> = {};
  Object.keys(process.env).forEach((key) => {
    if (key.startsWith("PUBLIC_NG_")) {
      config[key] = process.env[key];
    }
  });
  res.json(config);
});

export default route;

The Dockerfile for reference is:

# Use Node.js for building the Angular SSR app
FROM node:22 AS builder

# Set the working directory
WORKDIR /app

# Copy package.json and install dependencies
COPY package*.json ./
RUN npm ci

# Copy all files and build the Angular SSR app
COPY . .
RUN npm run build

# Use a minimal Node.js image to run the SSR server
FROM node:22-alpine AS server

# Set the working directory
WORKDIR /app

# Copy the built app from the builder stage
COPY --from=builder /app/dist /app/dist
COPY --from=builder /app/package.json /app

# Install serve to serve the SSR app
RUN npm install -g serve

# Expose the SSR server port
EXPOSE 4000

# Command to run the SSR server
CMD ["npm", "run", "serve:ssr"]

Exception or Error

0.233 > ng build
0.233
0.541 ❯ Building...
0.944 (node:20) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
0.944 (Use `node --trace-warnings ...` to show where the warning was created)
4.862 ERROR vt {
4.862   headers: e {
4.862     headers: Map(0) {},
4.862     normalizedNames: Map(0) {},
4.862     lazyInit: undefined,
4.862     lazyUpdate: null
4.862   },
4.862   status: 0,
4.862   statusText: 'Unknown Error',
4.862   url: 'http://localhost:37773/app-config',
4.862   ok: false,
4.862   type: undefined,
4.862   name: 'HttpErrorResponse',
4.862   message: 'Http failure response for http://localhost:37773/app-config: 0 undefined',
4.862   error: TypeError: fetch failed
4.862       at node:internal/deps/undici/undici:13178:13
4.862       at a.invoke (file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:3:6715)
4.862       at l.run (file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:3:1985)
4.862       at file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:4:576
4.862       at a.invokeTask (file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:3:7341)
4.862       at l.runTask (file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:3:2628)
4.862       at R (file:///app/.angular/prerender-root/6d2a3b7b-b719-4cf2-96bb-7b6c75bc01a4/polyfills.server.mjs:3:9382)
4.862       at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
4.862     [cause]: Error: connect ECONNREFUSED 127.0.0.1:37773
4.862         at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1607:16) {
4.862       errno: -111,
4.862       code: 'ECONNREFUSED',
4.862       syscall: 'connect',
4.862       address: '127.0.0.1',
4.862       port: 37773
4.862     }
4.862   }
4.862 }

Your Environment

Angular CLI: 19.0.2
Node: 20.18.0
Package Manager: npm 10.8.2
OS: win32 x64

Angular: 19.0.1
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, platform-server
... router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1900.2
@angular-devkit/build-angular   19.0.2
@angular-devkit/core            19.0.2
@angular-devkit/schematics      19.0.2
@angular/cli                    19.0.2
@angular/ssr                    19.0.2
@schematics/angular             19.0.2
rxjs                            7.8.1
typescript                      5.6.3
zone.js                         0.15.0

Anything else relevant?

If I put a try/catch around the http request and suppress the error the build succeeds.

[alan-agius4]

Can you try to replace node_modules/@angular/build/src/utils/server-rendering/launch-server.js to the below and check if the problem persists?

"use strict";
/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.DEFAULT_URL = void 0;
exports.launchServer = launchServer;
const node_assert_1 = __importDefault(require("node:assert"));
const node_http_1 = require("node:http");
const load_esm_1 = require("../load-esm");
const load_esm_from_memory_1 = require("./load-esm-from-memory");
const utils_1 = require("./utils");
exports.DEFAULT_URL = new URL('http://ng-localhost/');
/**
 * Launches a server that handles local requests.
 *
 * @returns A promise that resolves to the URL of the running server.
 */
async function launchServer() {
    const { reqHandler } = await (0, load_esm_from_memory_1.loadEsmModuleFromMemory)('./server.mjs');
    const { createWebRequestFromNodeRequest, writeResponseToNodeResponse } = await (0, load_esm_1.loadEsmModule)('@angular/ssr/node');
    if (!(0, utils_1.isSsrNodeRequestHandler)(reqHandler) && !(0, utils_1.isSsrRequestHandler)(reqHandler)) {
        return exports.DEFAULT_URL;
    }
    const server = (0, node_http_1.createServer)((req, res) => {
        (async () => {
            // handle request
            if ((0, utils_1.isSsrNodeRequestHandler)(reqHandler)) {
                await reqHandler(req, res, (e) => {
                    throw e;
                });
            }
            else {
                const webRes = await reqHandler(createWebRequestFromNodeRequest(req));
                if (webRes) {
                    await writeResponseToNodeResponse(webRes, res);
                }
                else {
                    res.statusCode = 501;
                    res.end('Not Implemented.');
                }
            }
        })().catch((e) => {
            res.statusCode = 500;
            res.end('Internal Server Error.');
            // eslint-disable-next-line no-console
            console.error(e);
        });
    });
    server.unref();
    await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
    const serverAddress = server.address();
    (0, node_assert_1.default)(serverAddress, 'Server address should be defined.');
    (0, node_assert_1.default)(typeof serverAddress !== 'string', 'Server address should not be a string.');
    return new URL(`http://${serverAddress.address}:${serverAddress.port}/`);
}