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Deployment

This page describes techniques for deploying your Angular application to a remote server.

Simplest deployment possible

For the simplest deployment, build for development and copy the output directory to a web server.

  1. Start with the development build

    ng build
  1. Copy everything within the output folder (dist/ by default) to a folder on the server.
  1. If you copy the files into a server sub-folder, append the build flag, --base-href and set the <base href> appropriately.

    For example, if the index.html is on the server at /my/app/index.html, set the base href to <base href="/my/app/"> like this.

    ng build --base-href=/my/app/

    You'll see that the <base href> is set properly in the generated dist/index.html. If you copy to the server's root directory, omit this step and leave the <base href> alone. Learn more about the role of <base href> below.

  1. Configure the server to redirect requests for missing files to index.html. Learn more about server-side redirects below.

This is not a production deployment. It's not optimized and it won't be fast for users. It might be good enough for sharing your progress and ideas internally with managers, teammates, and other stakeholders.

Optimize for production

Although deploying directly from the development environment works, you can generate an optimized build with additional CLI command line flags, starting with --prod.

Build with --prod

ng build --prod

The --prod meta-flag engages the following optimization features.

  • Ahead-of-Time (AOT) Compilation: pre-compiles Angular component templates.
  • Production mode: deploys the production environment which enables production mode.
  • Bundling: concatenates your many application and library files into a few bundles.
  • Minification: removes excess whitespace, comments, and optional tokens.
  • Uglification: rewrites code to use short, cryptic variable and function names.
  • Dead code elimination: removes unreferenced modules and much unused code.

The remaining copy deployment steps are the same as before.

You may further reduce bundle sizes by adding the build-optimizer flag.

ng build --prod --build-optimizer

See the CLI Documentation for details about available build options and what they do.

Enable production mode

Angular apps run in development mode by default, as you can see by the following message on the browser console:

Angular is running in the development mode. Call enableProdMode() to enable the production mode.

Switching to production mode can make it run faster by disabling development specific checks such as the dual change detection cycles.

Building for production (or appending the --environment=prod flag) enables production mode Look at the CLI-generated main.ts to see how this works.

Lazy loading

You can dramatically reduce launch time by only loading the application modules that absolutely must be present when the app starts.

Configure the Angular Router to defer loading of all other modules (and their associated code), either by waiting until the app has launched or by lazy loading them on demand.

Don't eagerly import something from a lazy loaded module

It's a common mistake. You've arranged to lazy load a module. But you unintentionally import it, with a JavaScript import statement, in a file that's eagerly loaded when the app starts, a file such as the root AppModule. If you do that, the module will be loaded immediately.

The bundling configuration must take lazy loading into consideration. Because lazy loaded modules aren't imported in JavaScript (as just noted), bundlers exclude them by default. Bundlers don't know about the router configuration and won't create separate bundles for lazy loaded modules. You have to create these bundles manually.

The CLI runs the Angular Ahead-of-Time Webpack Plugin which automatically recognizes lazy loaded NgModules and creates separate bundles for them.

Measure performance

You can make better decisions about what to optimize and how when you have a clear and accurate understanding of what's making the application slow. The cause may not be what you think it is. You can waste a lot of time and money optimizing something that has no tangible benefit or even makes the app slower. You should measure the app's actual behavior when running in the environments that are important to you.

The Chrome DevTools Network Performance page is a good place to start learning about measuring performance.

The WebPageTest tool is another good choice that can also help verify that your deployment was successful.

Inspect the bundles

The source-map-explorer tool is a great way to inspect the generated JavaScript bundles after a production build.

Install source-map-explorer:

npm install source-map-explorer --save-dev

Build your app for production including the source maps

ng build --prod --sourcemaps

List the generated bundles in the dist/ folder.

ls dist/*.bundle.js

Run the explorer to generate a graphical representation of one of the bundles. The following example displays the graph for the main bundle.

node_modules/.bin/source-map-explorer dist/main.*.bundle.js

The source-map-explorer analyzes the source map generated with the bundle and draws a map of all dependencies, showing exactly which classes are included in the bundle.

Here's the output for the main bundle of the QuickStart.

quickstart sourcemap explorer

The base tag

The HTML <base href="..."/> specifies a base path for resolving relative URLs to assets such as images, scripts, and style sheets. For example, given the <base href="/my/app/">, the browser resolves a URL such as some/place/foo.jpg into a server request for my/app/some/place/foo.jpg. During navigation, the Angular router uses the base href as the base path to component, template, and module files.

See also the APP_BASE_HREF alternative.

In development, you typically start the server in the folder that holds index.html. That's the root folder and you'd add <base href="/"> near the top of index.html because / is the root of the app.

But on the shared or production server, you might serve the app from a subfolder. For example, when the URL to load the app is something like http://www.mysite.com/my/app/, the subfolder is my/app/ and you should add <base href="/my/app/"> to the server version of the index.html.

When the base tag is mis-configured, the app fails to load and the browser console displays 404 - Not Found errors for the missing files. Look at where it tried to find those files and adjust the base tag appropriately.

build vs. serve

You'll probably prefer ng build for deployments.

The ng build command is intended for building the app and deploying the build artifacts elsewhere. The ng serve command is intended for fast, local, iterative development.

Both ng build and ng serve clear the output folder before they build the project. The ng build command writes generated build artifacts to the output folder. The ng serve command does not. It serves build artifacts from memory instead for a faster development experience.

The output folder is dist/ by default. To output to a different folder, change the outDir in .angular-cli.json.

The ng serve command builds, watches, and serves the application from a local CLI development server.

The ng build command generates output files just once and does not serve them. The ng build --watch command will regenerate output files when source files change. This --watch flag is useful if you're building during development and are automatically re-deploying changes to another server.

See the CLI build topic for more details and options.

Server configuration

This section covers changes you may have make to the server or to files deployed to the server.

Routed apps must fallback to index.html

Angular apps are perfect candidates for serving with a simple static HTML server. You don't need a server-side engine to dynamically compose application pages because Angular does that on the client-side.

If the app uses the Angular router, you must configure the server to return the application's host page (index.html) when asked for a file that it does not have.

A routed application should support "deep links". A deep link is a URL that specifies a path to a component inside the app. For example, http://www.mysite.com/heroes/42 is a deep link to the hero detail page that displays the hero with id: 42.

There is no issue when the user navigates to that URL from within a running client. The Angular router interprets the URL and routes to that page and hero.

But clicking a link in an email, entering it in the browser address bar, or merely refreshing the browser while on the hero detail page — all of these actions are handled by the browser itself, outside the running application. The browser makes a direct request to the server for that URL, bypassing the router.

A static server routinely returns index.html when it receives a request for http://www.mysite.com/. But it rejects http://www.mysite.com/heroes/42 and returns a 404 - Not Found error unless it is configured to return index.html instead.

Fallback configuration examples

There is no single configuration that works for every server. The following sections describe configurations for some of the most popular servers. The list is by no means exhaustive, but should provide you with a good starting point.

Development servers

  • Webpack-Dev-Server: setup the historyApiFallback entry in the dev server options as follows:

    historyApiFallback: {
          disableDotRule: true,
          htmlAcceptHeaders: ['text/html', 'application/xhtml+xml']
        }

Production servers

  • IIS: add a rewrite rule to web.config, similar to the one shown here:

    <system.webServer>
          <rewrite>
            <rules>
              <rule name="Angular Routes" stopProcessing="true">
                <match url=".*" />
                <conditions logicalGrouping="MatchAll">
                  <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                  <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                </conditions>
                <action type="Rewrite" url="/src/" />
              </rule>
            </rules>
          </rewrite>
        </system.webServer>

Requesting services from a different server (CORS)

Angular developers may encounter a cross-origin resource sharing error when making a service request (typically a data service request) to a server other than the application's own host server. Browsers forbid such requests unless the server permits them explicitly.

There isn't anything the client application can do about these errors. The server must be configured to accept the application's requests. Read about how to enable CORS for specific servers at enable-cors.org.

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https://angular.io/guide/deployment