Cognito Error during Android plugin registration: The client tried to add a plugin after calling configure.

[alextekartik]

Describe the bug

In some specific Android restart scenario AuthCognito plugin fails to register (typically the second time).

To Reproduce

Unfortunately I don't a small project to reproduce. But basically, there is a crash when:

• Having amplify_auth_cognito 0.0.1-dev.6
• Launch and login using AWS Cognito and flutter example
• exiting the Android application using Back (not killing the application)
• starting the application again from the android launcher (not the IDE)

Expected behavior

Pluging Registration ok. When plugin registration fails, we end up with a Missing Plugin Exception (that could happen on other plug).

Screenshots

I had to override GeneratedPluginRegistrant.registerWith to catch the logs in MainActivity.configureFlutterEngine with something like that

        String name = "AuthCognito";
        try {
            Log.e("StableApp", "registering " + name);
            flutterEngine.getPlugins().add(new com.amazonaws.amplify.amplify_auth_cognito.AuthCognito());
        } catch (Exception e) {
            Log.e("StableApp", "Error " + name, e);
        }

Logs:

    AmplifyException{message=The client tried to add a plugin after calling configure()., cause=null, recoverySuggestion=Plugins may not be added or removed after configure(...) is called.}
        at com.amplifyframework.core.Amplify.updatePluginRegistry(Amplify.java:195)
        at com.amplifyframework.core.Amplify.addPlugin(Amplify.java:175)
        at com.amazonaws.amplify.amplify_auth_cognito.AuthCognito.onAttachedToEngine(AuthCognito.kt:92)
        at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.add(FlutterEngineConnectionRegistry.java:143)
        at com.example.stable_app.StableAppPluginRegistrant.registerWith(StableAppPluginRegistrant.java:29)
        at com.example.stable_app.MainActivity.configureFlutterEngine(MainActivity.kt:10)
        at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach(FlutterActivityAndFragmentDelegate.java:180)
        at io.flutter.embedding.android.FlutterActivity.onCreate(FlutterActivity.java:409)

There are also some additiontial logs during Code initialization:

2021-01-19 15:44:59.408 29375-29375/? E/StableApp: registering AmplifyCore
2021-01-19 15:44:59.411 29375-29375/? W/System.err: java.io.FileNotFoundException: /jacoco.exec: open failed: EROFS (Read-only file system)
2021-01-19 15:44:59.411 29375-29375/? W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:496)
2021-01-19 15:44:59.411 29375-29375/? W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:235)
2021-01-19 15:44:59.411 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.output.FileOutput.openFile(FileOutput.java:67)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.output.FileOutput.startup(FileOutput.java:49)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.Agent.startup(Agent.java:122)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.Agent.getInstance(Agent.java:50)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.Offline.<clinit>(Offline.java:31)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at org.jacoco.agent.rt.internal_8ff85ea.Offline.getProbes(Offline.java:51)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at com.amazonaws.amplify.amplify_core.Core.$jacocoInit(Unknown Source:13)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at com.amazonaws.amplify.amplify_core.Core.<clinit>(Unknown Source:0)
2021-01-19 15:44:59.412 29375-29375/? W/System.err:     at com.example.stable_app.StableAppPluginRegistrant.registerWith(StableAppPluginRegistrant.java:22)

Platform

Amplify Flutter current supports iOS and Android. This issue is reproducible in (check all that apply):
[x] Android
[ ] iOS (not tested)

Smartphone (please complete the following information):

• Emulator API 29

Additional context

• I notice this issue first in release mode.
• All other plugins (path_provider, sqflite register correctly)
• If you kill the app and restart the app, it works fine. Quitting with back does not kill the java world and restarting again here cause the issue again.
• Sorry for not having a better description...

[fjnoyp]

Hi @alextekartik please see this issue: #99

This seems like an issue where the back button causes the FlutterActivity to be destroyed in Android instead of sending it to background. There are some workarounds mentioned here https://stackoverflow.com/questions/55539302/sending-your-application-to-background-when-back-button-is-pressed-in-flutter that can be used by the applications such as

https://medium.com/stuart-engineering/%EF%B8%8F-the-tricky-task-of-keeping-flutter-running-on-android-2d51bbc60882
https://www.programmersought.com/article/3839440802/

[alextekartik]

Thanks @fjnoyp for the info.

Pressing back is a common task, and killing the FlutterActivity can happen in low memory situation (which is hard to reproduce so pressing back is a way to mimic what would happen). Other plugins deal with the situation on the native side (i.e. the issue only happens with the cognito plugin for the 10+ plugins I have). If you get a Missing plugin exception on issue #99, it is just because the registration fails which could be solved on the native side.

[fjnoyp]

Thanks for that insight @alextekartik I'll investigate what you said.

[Amplifiyer]

This is fixed in #345 which will be part of next release. You would have to still catch the exception AmplifyAlreadyConfiguredException from Amplify.configure()