Flags to skip launching the emulator for `run-android`

Describe the Feature

In the current version, an emulator will be launched when we run react-native run-android ... and there is no way to skip launching it.

In my project, the use case of run-android is to run different gradle tasks like the following which doesn’t need the emulator at all.

$ react-native run-android --tasks clean,assembleRelease,uploadRelease

However, the emulator will be launched for every run of run-android and I have to close it again and again.

This is actually a dilemma that we can definitely use the original gradle cli. In this case, we need to run the jetifier on our own and this is not the optimal scenario.

Possible Implementations

Support a new flag, e.g. --no-emulator and add a condition at https://github.com/react-native-community/cli/blob/a5d837543dad8b3f40b4d2449963542e5d3abefe/packages/platform-android/src/commands/runAndroid/runOnAllDevices.ts#L39

Related Issues

n/a

[mauscoelho]

This can also help some CI like Bitrise, today when you run with the purpose of generating an apk you will get an error

$ react-native run-android --variant=release

Execution failed for task ':app:installRelease'.
> com.android.builder.testing.api.DeviceException: No connected devices!

We could avoid it using

$ react-native build-android --variant=release

[cortinico]

If anyone has an android device plugged in

That’s a workaround. The solution to this issue can’t be just “plug an android device”.

What I think we need is having build-android and build-ios that share their backend with run-* commands, but without starting Metro instance and booting up a simulator. We also need the --mode flag mentioned in #179.

+1 for this approach