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server.ts
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/**
* *** NOTE ON IMPORTING FROM ANGULAR AND NGUNIVERSAL IN THIS FILE ***
*
* If your application uses third-party dependencies, you'll need to
* either use Webpack or the Angular CLI's `bundleDependencies` feature
* in order to adequately package them for use on the server without a
* node_modules directory.
*
* However, due to the nature of the CLI's `bundleDependencies`, importing
* Angular in this file will create a different instance of Angular than
* the version in the compiled application code. This leads to unavoidable
* conflicts. Therefore, please do not explicitly import from @angular or
* @nguniversal in this file. You can export any needed resources
* from your application's main.server.ts file, as seen below with the
* import for `ngExpressEngine`.
*/
import 'zone.js/node';
import 'reflect-metadata';
/* eslint-disable import/no-namespace */
import * as morgan from 'morgan';
import * as express from 'express';
import * as ejs from 'ejs';
import * as compression from 'compression';
import * as expressStaticGzip from 'express-static-gzip';
/* eslint-enable import/no-namespace */
import axios from 'axios';
import LRU from 'lru-cache';
import isbot from 'isbot';
import { createCertificate } from 'pem';
import { createServer } from 'https';
import { json } from 'body-parser';
import { createHttpTerminator } from 'http-terminator';
import { readFileSync } from 'fs';
import { join } from 'path';
import { enableProdMode } from '@angular/core';
import { environment } from './src/environments/environment';
import { createProxyMiddleware } from 'http-proxy-middleware';
import { hasValue } from './src/app/shared/empty.util';
import { UIServerConfig } from './src/config/ui-server-config.interface';
import bootstrap from './src/main.server';
import { buildAppConfig } from './src/config/config.server';
import {
APP_CONFIG,
AppConfig,
} from './src/config/app-config.interface';
import { extendEnvironmentWithAppConfig } from './src/config/config.util';
import { logStartupMessage } from './startup-message';
import { TOKENITEM } from './src/app/core/auth/models/auth-token-info.model';
import { CommonEngine } from '@angular/ssr';
import { APP_BASE_HREF } from '@angular/common';
import {
REQUEST,
RESPONSE,
} from './src/express.tokens';
/*
* Set path for the browser application's dist folder
*/
const DIST_FOLDER = join(process.cwd(), 'dist/browser');
// Set path fir IIIF viewer.
const IIIF_VIEWER = join(process.cwd(), 'dist/iiif');
const indexHtml = join(DIST_FOLDER, 'index.html');
const cookieParser = require('cookie-parser');
const appConfig: AppConfig = buildAppConfig(join(DIST_FOLDER, 'assets/config.json'));
// cache of SSR pages for known bots, only enabled in production mode
let botCache: LRU<string, any>;
// cache of SSR pages for anonymous users. Disabled by default, and only available in production mode
let anonymousCache: LRU<string, any>;
// extend environment with app config for server
extendEnvironmentWithAppConfig(environment, appConfig);
// The Express app is exported so that it can be used by serverless Functions.
export function app() {
const router = express.Router();
/*
* Create a new express application
*/
const server = express();
// Tell Express to trust X-FORWARDED-* headers from proxies
// See https://expressjs.com/en/guide/behind-proxies.html
server.set('trust proxy', environment.ui.useProxies);
/*
* If production mode is enabled in the environment file:
* - Enable Angular's production mode
* - Initialize caching of SSR rendered pages (if enabled in config.yml)
* - Enable compression for SSR responses. See [compression](https://github.com/expressjs/compression)
*/
if (environment.production) {
enableProdMode();
initCache();
server.use(compression({
// only compress responses we've marked as SSR
// otherwise, this middleware may compress files we've chosen not to compress via compression-webpack-plugin
filter: (_, res) => res.locals.ssr,
}));
}
/*
* Enable request logging
* See [morgan](https://github.com/expressjs/morgan)
*/
server.use(morgan('dev'));
/*
* Add cookie parser middleware
* See [cookie-parser](https://github.com/expressjs/cookie-parser)
*/
server.use(cookieParser());
/*
* Add JSON parser for request bodies
* See [body-parser](https://github.com/expressjs/body-parser)
*/
server.use(json());
server.engine('ejs', ejs.renderFile);
/*
* Register the view engines for html and ejs
*/
server.set('view engine', 'html');
server.set('view engine', 'ejs');
/**
* Serve the robots.txt ejs template, filling in the origin variable
*/
server.get('/robots.txt', (req, res) => {
res.setHeader('content-type', 'text/plain');
res.render('assets/robots.txt.ejs', {
'origin': req.protocol + '://' + req.headers.host,
});
});
/*
* Set views folder path to directory where template files are stored
*/
server.set('views', DIST_FOLDER);
/**
* Proxy the sitemaps
*/
router.use('/sitemap**', createProxyMiddleware({
target: `${environment.rest.baseUrl}/sitemaps`,
pathRewrite: path => path.replace(environment.ui.nameSpace, '/'),
changeOrigin: true,
}));
/**
* Proxy the linksets
*/
router.use('/signposting**', createProxyMiddleware({
target: `${environment.rest.baseUrl}`,
pathRewrite: path => path.replace(environment.ui.nameSpace, '/'),
changeOrigin: true,
}));
/**
* Checks if the rateLimiter property is present
* When it is present, the rateLimiter will be enabled. When it is undefined, the rateLimiter will be disabled.
*/
if (hasValue((environment.ui as UIServerConfig).rateLimiter)) {
const RateLimit = require('express-rate-limit');
const limiter = new RateLimit({
windowMs: (environment.ui as UIServerConfig).rateLimiter.windowMs,
max: (environment.ui as UIServerConfig).rateLimiter.max,
});
server.use(limiter);
}
/*
* Serve static resources (images, i18n messages, …)
* Handle pre-compressed files with [express-static-gzip](https://github.com/tkoenig89/express-static-gzip)
*/
router.get('*.*', addCacheControl, expressStaticGzip(DIST_FOLDER, {
index: false,
enableBrotli: true,
orderPreference: ['br', 'gzip'],
}));
/*
* Fallthrough to the IIIF viewer (must be included in the build).
*/
router.use('/iiif', express.static(IIIF_VIEWER, { index: false }));
/**
* Checking server status
*/
server.get('/app/health', healthCheck);
/**
* Default sending all incoming requests to ngApp() function, after first checking for a cached
* copy of the page (see cacheCheck())
*/
router.get('*', cacheCheck, ngApp);
server.use(environment.ui.nameSpace, router);
return server;
}
/*
* The callback function to serve server side angular
*/
function ngApp(req, res, next) {
if (environment.ssr.enabled) {
// Render the page to user via SSR (server side rendering)
serverSideRender(req, res, next);
} else {
// If preboot is disabled, just serve the client
console.log('Universal off, serving for direct client-side rendering (CSR)');
clientSideRender(req, res);
}
}
/**
* Render page content on server side using Angular SSR. By default this page content is
* returned to the user.
* @param req current request
* @param res current response
* @param next the next function
* @param sendToUser if true (default), send the rendered content to the user.
* If false, then only save this rendered content to the in-memory cache (to refresh cache).
*/
function serverSideRender(req, res, next, sendToUser: boolean = true) {
const { protocol, originalUrl, baseUrl, headers } = req;
const commonEngine = new CommonEngine({ enablePerformanceProfiler: environment.ssr.enablePerformanceProfiler });
// Render the page via SSR (server side rendering)
commonEngine
.render({
bootstrap,
documentFilePath: indexHtml,
inlineCriticalCss: environment.ssr.inlineCriticalCss,
url: `${protocol}://${headers.host}${originalUrl}`,
publicPath: DIST_FOLDER,
providers: [
{ provide: APP_BASE_HREF, useValue: baseUrl },
{
provide: REQUEST,
useValue: req,
},
{
provide: RESPONSE,
useValue: res,
},
{
provide: APP_CONFIG,
useValue: environment,
},
],
})
.then((html) => {
if (hasValue(html)) {
// save server side rendered page to cache (if any are enabled)
saveToCache(req, html);
if (sendToUser) {
res.locals.ssr = true; // mark response as SSR (enables text compression)
// send rendered page to user
res.send(html);
}
}
})
.catch((err) => {
if (hasValue(err) && err.code === 'ERR_HTTP_HEADERS_SENT') {
// When this error occurs we can't fall back to CSR because the response has already been
// sent. These errors occur for various reasons in universal, not all of which are in our
// control to solve.
console.warn('Warning [ERR_HTTP_HEADERS_SENT]: Tried to set headers after they were sent to the client');
} else {
console.warn('Error in server-side rendering (SSR)');
if (hasValue(err)) {
console.warn('Error details : ', err);
}
if (sendToUser) {
console.warn('Falling back to serving direct client-side rendering (CSR).');
clientSideRender(req, res);
}
}
next(err);
});
}
/**
* Send back response to user to trigger direct client-side rendering (CSR)
* @param req current request
* @param res current response
*/
function clientSideRender(req, res) {
res.sendFile(indexHtml);
}
/*
* Adds a Cache-Control HTTP header to the response.
* The cache control value can be configured in the config.*.yml file
* Defaults to max-age=604,800 seconds (1 week)
*/
function addCacheControl(req, res, next) {
// instruct browser to revalidate
res.header('Cache-Control', environment.cache.control || 'max-age=604800');
next();
}
/*
* Initialize server-side caching of pages rendered via SSR.
*/
function initCache() {
if (botCacheEnabled()) {
// Initialize a new "least-recently-used" item cache (where least recently used pages are removed first)
// See https://www.npmjs.com/package/lru-cache
// When enabled, each page defaults to expiring after 1 day (defined in default-app-config.ts)
botCache = new LRU( {
max: environment.cache.serverSide.botCache.max,
ttl: environment.cache.serverSide.botCache.timeToLive,
allowStale: environment.cache.serverSide.botCache.allowStale,
});
}
if (anonymousCacheEnabled()) {
// NOTE: While caches may share SSR pages, this cache must be kept separately because the timeToLive
// may expire pages more frequently.
// When enabled, each page defaults to expiring after 10 seconds (defined in default-app-config.ts)
// to minimize anonymous users seeing out-of-date content
anonymousCache = new LRU( {
max: environment.cache.serverSide.anonymousCache.max,
ttl: environment.cache.serverSide.anonymousCache.timeToLive,
allowStale: environment.cache.serverSide.anonymousCache.allowStale,
});
}
}
/**
* Return whether bot-specific server side caching is enabled in configuration.
*/
function botCacheEnabled(): boolean {
// Caching is only enabled if SSR is enabled AND
// "max" pages to cache is greater than zero
return environment.ssr.enabled && environment.cache.serverSide.botCache.max && (environment.cache.serverSide.botCache.max > 0);
}
/**
* Return whether anonymous user server side caching is enabled in configuration.
*/
function anonymousCacheEnabled(): boolean {
// Caching is only enabled if SSR is enabled AND
// "max" pages to cache is greater than zero
return environment.ssr.enabled && environment.cache.serverSide.anonymousCache.max && (environment.cache.serverSide.anonymousCache.max > 0);
}
/**
* Check if the currently requested page is in our server-side, in-memory cache.
* Caching is ONLY done for SSR requests. Pages are cached base on their path (e.g. /home or /search?query=test)
*/
function cacheCheck(req, res, next) {
// Cached copy of page (if found)
let cachedCopy;
// If the bot cache is enabled and this request looks like a bot, check the bot cache for a cached page.
if (botCacheEnabled() && isbot(req.get('user-agent'))) {
cachedCopy = checkCacheForRequest('bot', botCache, req, res, next);
} else if (anonymousCacheEnabled() && !isUserAuthenticated(req)) {
cachedCopy = checkCacheForRequest('anonymous', anonymousCache, req, res, next);
}
// If cached copy exists, return it to the user.
if (cachedCopy && cachedCopy.page) {
if (cachedCopy.headers) {
Object.keys(cachedCopy.headers).forEach((header) => {
if (cachedCopy.headers[header]) {
if (environment.cache.serverSide.debug) {
console.log(`Restore cached ${header} header`);
}
res.setHeader(header, cachedCopy.headers[header]);
}
});
}
res.locals.ssr = true; // mark response as SSR-generated (enables text compression)
res.send(cachedCopy.page);
// Tell Express to skip all other handlers for this path
// This ensures we don't try to re-render the page since we've already returned the cached copy
next('router');
} else {
// If nothing found in cache, just continue with next handler
// (This should send the request on to the handler that rerenders the page via SSR
next();
}
}
/**
* Checks if the current request (i.e. page) is found in the given cache. If it is found,
* the cached copy is returned. When found, this method also triggers a re-render via
* SSR if the cached copy is now expired (i.e. timeToLive has passed for this cached copy).
* @param cacheName name of cache (just useful for debug logging)
* @param cache LRU cache to check
* @param req current request to look for in the cache
* @param res current response
* @param next the next function
* @returns cached copy (if found) or undefined (if not found)
*/
function checkCacheForRequest(cacheName: string, cache: LRU<string, any>, req, res, next): any {
// Get the cache key for this request
const key = getCacheKey(req);
// Check if this page is in our cache
const cachedCopy = cache.get(key);
if (cachedCopy) {
if (environment.cache.serverSide.debug) { console.log(`CACHE HIT FOR ${key} in ${cacheName} cache`); }
// Check if cached copy is expired (If expired, the key will now be gone from cache)
// NOTE: This will only occur when "allowStale=true", as it means the "get(key)" above returned a stale value.
if (!cache.has(key)) {
if (environment.cache.serverSide.debug) { console.log(`CACHE EXPIRED FOR ${key} in ${cacheName} cache. Re-rendering...`); }
// Update cached copy by rerendering server-side
// NOTE: In this scenario the currently cached copy will be returned to the current user.
// This re-render is performed behind the scenes to update cached copy for next user.
serverSideRender(req, res, next, false);
}
} else {
if (environment.cache.serverSide.debug) { console.log(`CACHE MISS FOR ${key} in ${cacheName} cache.`); }
}
// return page from cache
return cachedCopy;
}
/**
* Create a cache key from the current request.
* The cache key is the URL path (NOTE: this key will also include any querystring params).
* E.g. "/home" or "/search?query=test"
* @param req current request
* @returns cache key to use for this page
*/
function getCacheKey(req): string {
// NOTE: this will return the URL path *without* any baseUrl
return req.url;
}
/**
* Save page to server side cache(s), if enabled. If caching is not enabled or a user is authenticated, this is a noop
* If multiple caches are enabled, the page will be saved to any caches where it does not yet exist (or is expired).
* (This minimizes the number of times we need to run SSR on the same page.)
* @param req current page request
* @param page page data to save to cache
*/
function saveToCache(req, page: any) {
// Only cache if no one is currently authenticated. This means ONLY public pages can be cached.
// NOTE: It's not safe to save page data to the cache when a user is authenticated. In that situation,
// the page may include sensitive or user-specific materials. As the cache is shared across all users, it can only contain public info.
if (!isUserAuthenticated(req)) {
const key = getCacheKey(req);
// Avoid caching "/reload/[random]" paths (these are hard refreshes after logout)
if (key.startsWith('/reload')) { return; }
// Avoid caching not successful responses (status code different from 2XX status)
if (hasNotSucceeded(req.res.statusCode)) { return; }
// Retrieve response headers to save, if any
const headers = retrieveHeaders(req.res);
// If bot cache is enabled, save it to that cache if it doesn't exist or is expired
// (NOTE: has() will return false if page is expired in cache)
if (botCacheEnabled() && !botCache.has(key)) {
botCache.set(key, { page, headers });
if (environment.cache.serverSide.debug) { console.log(`CACHE SAVE FOR ${key} in bot cache.`); }
}
// If anonymous cache is enabled, save it to that cache if it doesn't exist or is expired
if (anonymousCacheEnabled() && !anonymousCache.has(key)) {
anonymousCache.set(key, { page, headers });
if (environment.cache.serverSide.debug) { console.log(`CACHE SAVE FOR ${key} in anonymous cache.`); }
}
}
}
/**
* Check if status code is different from 2XX
* @param statusCode
*/
function hasNotSucceeded(statusCode) {
const rgx = new RegExp(/^20+/);
return !rgx.test(statusCode);
}
function retrieveHeaders(response) {
const headers = Object.create({});
if (Array.isArray(environment.cache.serverSide.headers) && environment.cache.serverSide.headers.length > 0) {
environment.cache.serverSide.headers.forEach((header) => {
if (response.hasHeader(header)) {
if (environment.cache.serverSide.debug) {
console.log(`Save ${header} header to cache`);
}
headers[header] = response.getHeader(header);
}
});
}
return headers;
}
/**
* Whether a user is authenticated or not
*/
function isUserAuthenticated(req): boolean {
// Check whether our DSpace authentication Cookie exists or not
return req.cookies[TOKENITEM];
}
/*
* Callback function for when the server has started
*/
function serverStarted() {
console.log(`[${new Date().toTimeString()}] Listening at ${environment.ui.baseUrl}`);
}
/*
* Create an HTTPS server with the configured port and host
* @param keys SSL credentials
*/
function createHttpsServer(keys) {
const listener = createServer({
key: keys.serviceKey,
cert: keys.certificate,
}, app()).listen(environment.ui.port, environment.ui.host, () => {
serverStarted();
});
// Graceful shutdown when signalled
const terminator = createHttpTerminator({ server: listener });
process.on('SIGINT', () => {
void (async ()=> {
console.debug('Closing HTTPS server on signal');
await terminator.terminate().catch(e => { console.error(e); });
console.debug('HTTPS server closed');
})();
});
}
/**
* Create an HTTP server with the configured port and host.
*/
function run() {
const port = environment.ui.port || 4000;
const host = environment.ui.host || '/';
// Start up the Node server
const server = app();
const listener = server.listen(port, host, () => {
serverStarted();
});
// Graceful shutdown when signalled
const terminator = createHttpTerminator({ server: listener });
process.on('SIGINT', () => {
void (async () => {
console.debug('Closing HTTP server on signal');
await terminator.terminate().catch(e => { console.error(e); });
console.debug('HTTP server closed.');return undefined;
})();
});
}
function start() {
logStartupMessage(environment);
/*
* If SSL is enabled
* - Read credentials from configuration files
* - Call script to start an HTTPS server with these credentials
* When SSL is disabled
* - Start an HTTP server on the configured port and host
*/
if (environment.ui.ssl) {
let serviceKey;
try {
serviceKey = readFileSync('./config/ssl/key.pem');
} catch (e) {
console.warn('Service key not found at ./config/ssl/key.pem');
}
let certificate;
try {
certificate = readFileSync('./config/ssl/cert.pem');
} catch (e) {
console.warn('Certificate not found at ./config/ssl/key.pem');
}
if (serviceKey && certificate) {
createHttpsServer({
serviceKey: serviceKey,
certificate: certificate,
});
} else {
console.warn('Disabling certificate validation and proceeding with a self-signed certificate. If this is a production server, it is recommended that you configure a valid certificate instead.');
process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0'; // lgtm[js/disabling-certificate-validation]
createCertificate({
days: 1,
selfSigned: true,
}, (error, keys) => {
createHttpsServer(keys);
});
}
} else {
run();
}
}
/*
* The callback function to serve health check requests
*/
function healthCheck(req, res) {
const baseUrl = `${environment.rest.baseUrl}${environment.actuators.endpointPath}`;
axios.get(baseUrl)
.then((response) => {
res.status(response.status).send(response.data);
})
.catch((error) => {
res.status(error.response.status).send({
error: error.message,
});
});
}
// Webpack will replace 'require' with '__webpack_require__'
// '__non_webpack_require__' is a proxy to Node 'require'
// The below code is to ensure that the server is run only when not requiring the bundle.
declare const __non_webpack_require__: NodeRequire;
const mainModule = __non_webpack_require__.main;
const moduleFilename = (mainModule && mainModule.filename) || '';
if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
start();
}
export * from './src/main.server';