CODEWITHSUNDEEP
angularangular-cli
david.emilsson
david.emilsson

Reputation: 2331

Angular CLI build using base-href and deploy-url to access assets on CDN

The background

I'm using Angular CLI to build a project (with multiple apps). I want to publish the apps on separate sub-paths on my domain, like example.com/apps/app1/.

If I set the --base-href parameter to /apps/app1/ it solves any issues regarding the router, and it will load the assets (JS, CSS, and images etc) just fine.

If I use the Location service, I can use

this.location.prepareExternalUrl('/assets/data/data.json')

to resolve dynamically loaded assets (they will resolve to /apps/app1/assets/data/data.json).

So far so good. But I now want to serve the app assets through a CDN, such as cdn.example.com, while hosting the app itself on the original URL example.com/apps/app1/`. So now I build the app using:

 ng build -prod --app app1 --base-href "/apps/app1/" --deploy-url "http://cdn.example.com/app-assets/apps/app1/"

This time, I apply both the --base-href and --deploy-url parameters. It works great in that it uses the base-href to help the Router resolve the URL and it loads the js and CSS files from the CDN. It also resolves the image URL references in the CSS files using the CDN URL.

The problem

When loading images or data from the assets folder dynamically (in a service or template), I can't find a good way for it to resolve the URLs using the deploy-url configuration.

If I use the Location service, it still uses the base-href to resolve URLs, so

this.location.prepareExternalUrl('/assets/data/data.json')

will still resolve to /apps/app1/assets/data/data.json instead of http://cdn.example.com/app-assets/apps/app1/assets/data/data.json.

I would have expected it to use the deploy-url value if one is defined, especially since that would be a general solution that would work when hosting the files on the same domain and when hosting the files on an external domain.

The question

Is there a way to resolve the asset URLs considering both the base-href and the deploy-url parameters?

Ideally an official Angular function like Location.prepareExternalUrl, but if I can get the base-href and deploy-url parameters from Angular in some way, I could build my own service for it.

I would not want to define the URLs in the environment config since:

  1. It would require specific environment configs per app
  2. It creates a potential conflict with the values that are supplied when building the app.

Upvotes: 43

Views: 23300

Answers (5)

Valera Tumash
Valera Tumash

Reputation: 641

Angular 14.2+ (2022)

You can use NgOptimizedImage directive to load images from CDN URL. The most basic set-up using environments files with different URL for different environments is below:

// app.module.ts
import { NgOptimizedImage } from '@angular/common';
...
providers: [{
    provide: IMAGE_LOADER,
    useValue: (config: ImageLoaderConfig) => {
      return `${environment.imageURL}${config.src}`;
    },
}],
...

// component.html
<img ngSrc="assets/images/image.svg" width="100" height="100"/>

Upvotes: 0

Andre Elrico
Andre Elrico

Reputation: 11490

Here is how I solve this "BS"-problem. When your app is for e.g. hosted under www.domain.de/hehe.

  1. in angular.json add "deployUrl": "./",
  2. in src/index.html inside <head> add/update <base href="./">
  3. throughout your app you will use relative paths for assets and whatnot: <img src="./assets/img/pictureOfMyCrazyWife.png">
  4. just run ng build or ng build --prod conveniently.

with those simple steps you have a general setup. So it will work no matter if its www.domain.de/hehe, www.domain.de/hehe2, www.domain.de/ or www.domain.de/lol

Upvotes: 4

DevMike
DevMike

Reputation: 1821

I ran into this exact same situation, and as you outlined in The Background, building with both the base-href and deploy-url set does work in that we're able to serve up our css and js files from a CDN while hosting the application on another server.

As a solution to dynamically loaded assets in our templates, we wrote an API that delivers environment variables for this purpose which delivers the appropriate URLs needed per deployment.

Upvotes: 0

Marcin Majkowski
Marcin Majkowski

Reputation: 420

To access --deploy-url value at application runtime, create deploy-url.ts with:

export const DEPLOY_URL = new InjectionToken<string>('deployUrl');

And use this snippet in your main.ts file:

const deployUrl = (function() {
  const scripts = document.getElementsByTagName('script');
  const index = scripts.length - 1;
  const mainScript = scripts[index];
  return mainScript.src.replace(/main.*?\.js$/, '');
})();

const DEPLOY_URL_PROVIDER = {
  provide: DEPLOY_URL,
  useValue: deployUrl,
};

platformBrowserDynamic([DEPLOY_URL_PROVIDER])
  .bootstrapModule(AppModule)
  .catch(err => console.error(err));

The idea is to get the url of currently executed Javascript file, which is main.js (or main.hash.js if outputHashing is enabled) and strip filename from it. Then in your services inject --deploy-url value with @Inject(DEPLOY_URL) deployUrl: string as a constructor parameter.

Upvotes: 8

fernando
fernando

Reputation: 717

Here is how I have done for few projects.

Set the APP_BASE_HREF using a dynamic value set by server E.g. Cookie and SPA reads it on init. getBaseUrl function simply read a cookie value.

{ provide: APP_BASE_HREF, useFactory: () => getBaseUrl() }

Set the deployUrl as part of your CI process. You need to set the BUILD and VERSION dynamically. This can be done by using a simple shell script. 

https://my-cloud.cloudfront.net/my-app/{BUILD}/{VERSION}/

Upvotes: -2

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