How to explicitly point my service account file in code

Question

In other Google Services such as Storage, BigQuery you can define what service account you are going to use in the JAVA code:

// You can specify a credential file by providing a path to GoogleCredentials.
// Otherwise credentials are read from the GOOGLE_APPLICATION_CREDENTIALS environment variable.
  GoogleCredentials credentials = GoogleCredentials.fromStream(new FileInputStream(jsonPath))
        .createScoped(Lists.newArrayList("https://www.googleapis.com/auth/cloud-platform"));
  Storage storage = StorageOptions.newBuilder().setCredentials(credentials).build().getService();

Using Google Secret Manager it seems not possibile. Why? The only way is to set an environment variable on VM?

I tried as suggested to use Credentials Provider

 GoogleCredentials credentials = ServiceAccountCredentials.fromStream(credentialsInputStream);
     CredentialsProvider credentialsProvider = FixedCredentialsProvider.create(credentials);
     SecretManagerServiceSettings settings = SecretManagerServiceSettings.newBuilder().setCredentialsProvider(credentialsProvider).build();
     client = SecretManagerServiceClient.create(settings);

but it doesn't work

Caused by: java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkArgument(ZLjava/lang/String;CLjava/lang/Object;)V
    at io.grpc.Metadata$Key.validateName(Metadata.java:742)
    at io.grpc.Metadata$Key.<init>(Metadata.java:750)
    at io.grpc.Metadata$Key.<init>(Metadata.java:668)
    at io.grpc.Metadata$AsciiKey.<init>(Metadata.java:959)
    at io.grpc.Metadata$AsciiKey.<init>(Metadata.java:954)
    at io.grpc.Metadata$Key.of(Metadata.java:705)
    at io.grpc.Metadata$Key.of(Metadata.java:701)
    at com.google.api.gax.grpc.GrpcHeaderInterceptor.<init>(GrpcHeaderInterceptor.java:60)
    at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.createSingleChannel(InstantiatingGrpcChannelProvider.java:239)
    at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.access$1600(InstantiatingGrpcChannelProvider.java:71)
    at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider$1.createSingleChannel(InstantiatingGrpcChannelProvider.java:210)
    at com.google.api.gax.grpc.ChannelPool.create(ChannelPool.java:72)
    at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.createChannel(InstantiatingGrpcChannelProvider.java:217)
    at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.getTransportChannel(InstantiatingGrpcChannelProvider.java:200)
    at com.google.api.gax.rpc.ClientContext.create(ClientContext.java:156)
    at com.google.cloud.secretmanager.v1.stub.GrpcSecretManagerServiceStub.create(GrpcSecretManagerServiceStub.java:237)
    at com.google.cloud.secretmanager.v1.stub.SecretManagerServiceStubSettings.createStub(SecretManagerServiceStubSettings.java:226)
    at com.google.cloud.secretmanager.v1.SecretManagerServiceClient.<init>(SecretManagerServiceClient.java:154)
    at com.google.cloud.secretmanager.v1.SecretManagerServiceClient.create(SecretManagerServiceClient.java:135)

because of an Exception in the class com.google.cloud.secretmanager.v1.SecretManagerServiceClient

/**
   * Constructs an instance of SecretManagerServiceClient, using the given settings. This is
   * protected so that it is easy to make a subclass, but otherwise, the static factory methods
   * should be preferred.
   */
  protected SecretManagerServiceClient(SecretManagerServiceSettings settings) throws IOException {
    this.settings = settings;
    this.stub = ((SecretManagerServiceStubSettings) settings.getStubSettings()).createStub();
  }

Answer 1

To customize credentials, you can create a custom secretManagerServiceSettings:

SecretManagerServiceSettings secretManagerServiceSettings =
    SecretManagerServiceSettings.newBuilder()
        .setCredentialsProvider(FixedCredentialsProvider.create(credentials))
        .build();

SecretManagerServiceClient client =
    SecretManagerServiceClient.create(secretManagerServiceSettings);