배경

• Gradle 8로 업데이트하고 FirebaseInstallationServiceClient 관련해서 Crashlytics에 급격하게 리포트가 되기 시작했다.

로그

• 재현은 되지 않아서 Crashlytics 로그에만 의존했다.

Fatal Exception: java.lang.AbstractMethodError: abstract method "H.c H.c.G(int)"
       at com.google.firebase.installations.remote.FirebaseInstallationServiceClient.readGenerateAuthTokenResponse(FirebaseInstallationServiceClient.java:90)
       at com.google.firebase.installations.remote.FirebaseInstallationServiceClient.b(FirebaseInstallationServiceClient.java:94)
       at com.google.firebase.installations.FirebaseInstallations.fetchAuthTokenFromServer(FirebaseInstallations.java:31)
       at com.google.firebase.installations.FirebaseInstallations.doNetworkCallIfNecessary(FirebaseInstallations.java:66)
       at com.google.firebase.installations.FirebaseInstallations.lambda$doRegistrationOrRefresh$3(FirebaseInstallations.java:66)
       at com.google.firebase.concurrent.SequentialExecutor$1.run(SequentialExecutor.java:9)
       at com.google.firebase.concurrent.SequentialExecutor$QueueWorker.workOnQueue(SequentialExecutor.java:1)
       at com.google.firebase.concurrent.SequentialExecutor$QueueWorker.run(SequentialExecutor.java:13)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:644)
       at com.google.firebase.concurrent.CustomThreadFactory.lambda$newThread$0(CustomThreadFactory.java:13)
       at com.google.firebase.concurrent.CustomThreadFactory$$ExternalSyntheticLambda0.run(R8$$SyntheticClass:15)
       at java.lang.Thread.run(Thread.java:1012)

• 로그를 보니 난독화 이슈로 보인다.

원인

• Gradle 8 버전으로 업데이트되면서, FirebaseInstallationServiceClient 코드에 난독화가 되어 메서드를 찾지 못했다.
  • Gradle 8버전으로 올리게 되면, 기본적으로 fullMode가 활성화된다.
  • 간단하게 이야기하자면, 난독화를 좀 더 적극적으로 진행한다고 이해하면 된다.
  • 이로 인해, 기존에는 난독화가 되지 않았던 부분들이 난독화되는 경우가 발생한다.

대책

• proguard rule에 FirebaseInstallationServiceClient와 관련된 코드들을 추가했다.

-keep class com.google.firebase.installations.** { *; }
-keep interface com.google.firebase.installations.** { *; }

참고

• ref. Breaking changes: build option default values
• ref. R8 full mode
• ref. https://github.com/firebase/firebase-android-sdk/issues/3507