[annoyance] SPA development webserver starts twice when vite takes longer to start

[laingsimon]

Not sure if this is caused by the SPA app within dotnet or npm start. It is also possible, with a slow start, that the browser - Chrome - refreshes the page causing the backend to relaunch the server.

Either way the npm or spa dotnet app should prevent a double launch of the dev server

If possible, it would be useful for the spa app to launch npm start in a background window

courage_scores/CourageScores/CourageScores.csproj

Lines 11 to 12 in 0713d27

	<SpaProxyServerUrl>https://localhost:44426</SpaProxyServerUrl>
	<SpaProxyLaunchCommand>npm start</SpaProxyLaunchCommand>

Nuget Package: Microsoft.AspNetCore.SpaProxy

• src: https://github.com/dotnet/aspnetcore/tree/main/src/Middleware/Spa/SpaProxy

[laingsimon]

This could be vitejs or the dotnet core spa app, difficult to tell. It doesn't happen all the time, so suspect it is related to a slower than normal launch after a fresh build or branch switch

[laingsimon]

A change to this line would allow the window to open in the background/minimised

https://github.com/dotnet/aspnetcore/blob/708f27145d0f0fbb2910e7645f9c545c36838c45/src/Middleware/Spa/SpaProxy/src/SpaProxyLaunchManager.cs#L196

[laingsimon]

There is some unnecessary duplication in the SPA proxy launch manager:

IsSpaProxyRunning can call directly onto the ProbeSpaDevelopmentServerUrl (after creating a HttpClient). The methods are identical otherwise.

[laingsimon]

Suspected cause:

• SpaProxyStartupFilter calls StartInBackground (via StartIfNotRunning)
  • The proxy back-end is started (via npm start)
  • The proxy back-end takes longer than expected (due to creating a cert, or for other reasons)
• SpaProxyStartupFilter.Configure is called again (assumed)
  • IsSpaProxyRunning returns false (the proxy back-end doesn't respond with a HTTP 200-OK to the request)
  • The SpaProxyStartupFilter calls StartInBackground again - causing another instance of the back-end to be created
  • See note 1

---

Note 1:
At this point the first process is orphaned, as the reference to it _spaProcess is rewritten to the details of the second process

---

Suggested changes:

1. If _spaProcess is set to an instance, either:
   1. Terminate it before starting a new proxy back-end
   2. Wait for the process to exit before starting a new proxy back-end
   3. Defer to the existing process, i.e. dont create a new process
   4. Control this behaviour via a configuration switch (to retain existing behaviour if anyone requires it)
2. Add new config settings:
   1. SubsequentStartMethod: ReLaunch (default, start another process) | Restart (kill and start another process) | WaitForFirst (trust the first process will get there eventually)
   2. WindowStyle: Normal (allow the os to position the window) | Minimized (minimize the process if the os allows it)
   3. Use this configuration to allow the proxy back-end console window to be minimised (hidden) by default

[laingsimon]

See changes here: dotnet/aspnetcore#55375

[laingsimon]

Suggestion rejected by aspnet core developers. Remaining options are to:

• run a pre-start script
• stop using the spaproxy (not sure what other options there are)