Angular-cli: ng build --watch does not generate ngsw pwa workers.

[axos88]

🐞 Bug report

ng build --watch does not generate ngsw-worker.js, and siblings.

Command (mark with an x)

• [ ] new
• [x] build
• [ ] serve
• [ ] test
• [ ] e2e
• [ ] generate
• [ ] add
• [ ] update
• [ ] lint
• [ ] xi18n
• [ ] run
• [ ] config
• [ ] help
• [ ] version
• [ ] doc

Is this a regression?

Not sure. Had the same problem with angular 8, figured out it was the watch flag only after i upgraded to 9.

Description

ng build --watch --prod: no ngsw-worker & siblings under dist/project
ng build --watch --prod: ngsw-worker & siblings are generated under dist/project

🔬 Minimal Reproduction

new new foo
cd foo
ng add @angular/pwa
ng build --watch --prod

🌍 Your Environment

     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/


Angular CLI: 9.0.1
Node: 10.17.0
OS: linux x64

Angular: 9.0.0
... animations, common, compiler, compiler-cli, core, forms
... language-service, localize, platform-browser
... platform-browser-dynamic, router, service-worker
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.900.1
@angular-devkit/build-angular     0.900.1
@angular-devkit/build-optimizer   0.900.1
@angular-devkit/build-webpack     0.900.1
@angular-devkit/core              9.0.1
@angular-devkit/schematics        9.0.1
@angular/cli                      9.0.1
@ngtools/webpack                  9.0.1
@schematics/angular               9.0.1
@schematics/update                0.900.1
rxjs                              6.5.4
typescript                        3.7.5
webpack                           4.41.2

[alan-agius4]

This is actually by design. Maybe @clydin would know the exactly details why under watch these are not generated though.

[axos88]

Well, I just pulled my remaining hairs out by design then...

At least a warning and an option to turn this off would be great, because I am usually working with ng build --watch running in the background, and spent hours trying to figure out why they don't get generated

[dgp1130]

Talked with @clydin today and it seems that ng build --watch currently does not build service workers because ng serve does not build service workers because we don't currently have a good means of running a PWA locally (there are a few requirements, such as SSL, that are hard to satisfy locally).

As a result, this seems to be mostly an oversight. We don't see any reason ng build --watch _shouldn't_ build a service worker, it's only ng serve where that doesn't work out. In fact, applications may want to use ng build --watch and then serve it with a custom stack to manually fulfill those PWA requirements.

Most likely somewhere in the CLI we are checking if (!buildOptions.watch) { buildServiceWorker(); } when we should be doing if (buildCommand !== 'serve') { buildServiceWorker(); }.

This is just a bug we'll need to look into more.

[axos88]

https://stackoverflow.com/a/34161385
"There's an exception to the HTTPS requirement in place to facilitate local development: if you access your page and service worker script via http://localhost[:port], or via http://127.x.y.z[:port], then service workers should be enabled without any further actions."

So serving a PWA locally shouldn't be a problem anymore, and also there may be more complicated setups where there is a valid certificate in place, for example I am using ng serve to serve PWA locally. I have an SSL certificate for a domain I own, and set up port forwarding for that host to my locally served application. I am using this for development only of course, and would benefit from ng serve --watch building the PWA files to be served.

[dgp1130]

Should also look into ng serve building the service worker as well as ng build --watch per #10483.

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