Make sure flutter attach can work on android/ios device/simulator debug/profile without parameters

[xster]

Internal: b/117557861

@dnfield, I opened an issue for tracking

[xster]

Related #31872

[xster]

@dnfield, you were looking at Android mDNS but I forgot where that conversation ended.

[jonahwilliams]

For this to work entirely without parameters we'd need to add the capability to broadcast whether we're in debug/profile mode too

[xster]

Can you elaborate? Is this just for us to be able to provide a nicer message than can't connect on release mode?

[jonahwilliams]

The service protocols for hot reload/restart don't exist in profile mode since it is AOT, but we don't know how to fallback gracefully so we rely on the user to suggest with --profile. We could add that capability, but then we run the risk of not exiting if we fail to connect to a debug build

[dnfield]

I don't think Android mDNS will work. Unlike on iOS, there's no networking bridge set up to use - except on the emulator, where multicast packets are documented as not being supported. We'd need a different solution for Android.

[jonahwilliams]

We could create a secondary daemon which is always scanning logs and tracking open/closed dart observatories. Then attach talks to this daemon instead of log scanning.

[jonahwilliams]

This is similar to the attach monitor idea from @xster

[xster]

@jmagman: perhaps a 'starter project' to consider once you're done with explorations

[xster]

Might be related to the profile points above. Customer's reporting:

Waiting for a connection from Flutter on SM G9600...
Done.
Error -32603 received from application: Internal error
Error initializing DevFS: JSON-RPC error -32603 (internal error): Internal error

on Android