I'm trying to create a Function App to be triggered by blob storage events, and would like to retrieve the file metadata fields to use as parameters to file processing logic.
But when I declare @BlobTrigger in a BlobClient blobClient, raises the exception below. If I change to String content (or byte[]) the trigger works as expected.
I tried to remove gson as a indirect dependency in pom.xml, also tried to declare jackson to be the default serialized, but no success.
I managed to create by hand the blobClient and reach the file metadata, but I think that's not the right approach.
Am I missing something ?
Thanks in advance
Reference: Azure Blob storage trigger for Azure Functions
Code snippet:
@FunctionName("processBlob")
public void run(
@BlobTrigger(name = "content", path = "%GATEWAY_CONTAINER_NAME%%GATEWAY_SOURCE_FOLDER%/{fileName}", connection = "SourceBlogStorageConnStr", dataType = "binary") BlobClient blobClient,
@BindingName("fileName") String fileName,
ExecutionContext ctx) {
ctx.getLogger().info("Size = " + blobClient.getProperties().getBlobSize());
ctx.getLogger().info("Filename = " + fileName);
ctx.getLogger().info("Metadata = " + blobClient.getProperties().getMetadata().entrySet());
}
Output:
Executing 'Functions.processBlob' (Reason='New blob detected(LogsAndContainerScan): my_blob_storage/my_folder/my_file.csv', Id=bb2845c7-9d8c-4ecd-b6e0-21b42b73a345)
[2025-07-09T20:58:04.183Z] Trigger Details: MessageId: 28459ab1-e4de-4c2d-9bfb-901df92c32de, DequeueCount: 1, InsertedOn: 2025-07-09T20:58:03.000+00:00, BlobCreated: 2025-07-09T17:55:50.000+00:00, BlobLastModified: 2025-07-09T20:58:02.000+00:00
[2025-07-09T20:58:04.209Z] Executed 'Functions.processBlob' (Failed, Id=bb2845c7-9d8c-4ecd-b6e0-21b42b73a345, Duration=30ms)
[2025-07-09T20:58:04.209Z] System.Private.CoreLib: Exception while executing function: Functions.processBlob. System.Private.CoreLib: Result: Failure
[2025-07-09T20:58:04.209Z] Exception: IllegalArgumentException: Class com.azure.storage.blob.specialized.BlockBlobClient declares multiple JSON fields named 'client'; conflict is caused by fields com.azure.storage.blob.specialized.BlockBlobClient#client and com.azure.storage.blob.specialized.BlobClientBase#client
[2025-07-09T20:58:04.209Z] See https://github.com/google/gson/blob/main/Troubleshooting.md#duplicate-fields
[2025-07-09T20:58:04.210Z] Stack: java.lang.IllegalArgumentException: Class com.azure.storage.blob.specialized.BlockBlobClient declares multiple JSON fields named 'client'; conflict is caused by fields com.azure.storage.blob.specialized.BlockBlobClient#client and com.azure.storage.blob.specialized.BlobClientBase#client
[2025-07-09T20:58:04.210Z] See https://github.com/google/gson/blob/main/Troubleshooting.md#duplicate-fields
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createDuplicateFieldException(ReflectiveTypeAdapterFactory.java:313)
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:409)
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:161)
[2025-07-09T20:58:04.210Z] at com.google.gson.Gson.getAdapter(Gson.java:628)
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:201)
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:395)
[2025-07-09T20:58:04.210Z] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:161)
[2025-07-09T20:58:04.210Z] at com.google.gson.Gson.getAdapter(Gson.java:628)
[2025-07-09T20:58:04.211Z] at com.google.gson.Gson.fromJson(Gson.java:1360)
[2025-07-09T20:58:04.211Z] at com.google.gson.Gson.fromJson(Gson.java:1262)
[2025-07-09T20:58:04.211Z] at com.google.gson.Gson.fromJson(Gson.java:1171)
[2025-07-09T20:58:04.211Z] at com.google.gson.Gson.fromJson(Gson.java:1137)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.DataOperations.convertFromJson(DataOperations.java:158)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.DataOperations.apply(DataOperations.java:114)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.DataSource.computeByType(DataSource.java:56)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.RpcStringDataSource.computeByType(RpcStringDataSource.java:5)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.DataSource.computeByName(DataSource.java:42)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.RpcStringDataSource.computeByName(RpcStringDataSource.java:5)
[2025-07-09T20:58:04.211Z] at com.microsoft.azure.functions.worker.binding.BindingDataStore.getDataByName(BindingDataStore.java:66)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.binding.ExecutionContextDataSource.getBindingData(ExecutionContextDataSource.java:181)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolve(ParameterResolver.java:44)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolveArguments(ParameterResolver.java:22)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.broker.EnhancedJavaMethodExecutorImpl.execute(EnhancedJavaMethodExecutorImpl.java:20)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.chain.FunctionExecutionMiddleware.invoke(FunctionExecutionMiddleware.java:19)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.chain.InvocationChain.doNext(InvocationChain.java:21)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.broker.JavaFunctionBroker.invokeMethod(JavaFunctionBroker.java:195)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:34)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:10)
[2025-07-09T20:58:04.212Z] at com.microsoft.azure.functions.worker.handler.MessageHandler.handle(MessageHandler.java:44)
[2025-07-09T20:58:04.213Z] at com.microsoft.azure.functions.worker.JavaWorkerClient$StreamingMessagePeer.lambda$onNext$0(JavaWorkerClient.java:94)
[2025-07-09T20:58:04.213Z] at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
[2025-07-09T20:58:04.213Z] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[2025-07-09T20:58:04.213Z] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[2025-07-09T20:58:04.213Z] at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[2025-07-09T20:58:04.213Z] at java.base/java.lang.Thread.run(Thread.java:840)
This works:
@FunctionName("processBlob")
public void run(
@BlobTrigger(name = "content", path = "%GATEWAY_CONTAINER_NAME%%GATEWAY_SOURCE_FOLDER%/{fileName}", connection = "SourceBlogStorageConnStr", dataType = "string") String content,
@BindingName("fileName") String fileName,
ExecutionContext ctx) {
BlobServiceClient blobServiceClient = new BlobServiceClientBuilder()
.connectionString(System.getenv("GATEWAY_CONN_STRING"))
.buildClient();
BlobContainerClient containerClient = blobServiceClient
.getBlobContainerClient(
System.getenv("GATEWAY_CONTAINER_NAME") + System.getenv("GATEWAY_SOURCE_FOLDER"));
BlobClient blobClient = containerClient.getBlobClient(fileName);
ctx.getLogger().info("Size = " + blobClient.getProperties().getBlobSize());
ctx.getLogger().info("Filename = " + fileName);
ctx.getLogger().info("Metadata = " + blobClient.getProperties().getMetadata().entrySet());
}
[2025-07-09T21:37:02.435Z] Executing 'Functions.processBlob' (Reason='New blob detected(LogsAndContainerScan): my_blob_storage/my_folder/my_file.csv', Id=bb2845c7-9d8c-4ecd-b6e0-21b42b73a345)
[2025-07-09T21:37:02.435Z] Trigger Details: MessageId: 4726d7c3-558e-4d52-81f1-88fda86286c6, DequeueCount: 1, InsertedOn: 2025-07-09T21:37:02.000+00:00, BlobCreated: 2025-07-09T17:55:50.000+00:00, BlobLastModified: 2025-07-09T21:37:01.000+00:00
[2025-07-09T21:37:02.608Z] SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
[2025-07-09T21:37:02.609Z] SLF4J: Defaulting to no-operation (NOP) logger implementation
[2025-07-09T21:37:02.609Z] SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[2025-07-09T21:37:08.580Z] Size = 1236484
[2025-07-09T21:37:08.581Z] Filename = my_file.csv
[2025-07-09T21:37:08.581Z] Metadata = [Metadata3=value, Metadata4=value, Metadata5=value, Metadata1=value, Metadata2=value]
[2025-07-09T21:37:08.581Z] Function "processBlob" (Id: 1dc69e2a-682e-47ca-9805-2094f1ab1cf5) invoked by Java Worker
[2025-07-09T21:37:08.591Z] Executed 'Functions.processBlob' (Succeeded, Id=1dc69e2a-682e-47ca-9805-2094f1ab1cf5, Duration=6196ms)
I managed to obtain the expected behavior, just missing SDK parameters required configuration described in a different page, in Requirements.
Set the JAVA_ENABLE_SDK_TYPES app setting to true to enable SDK types.
azure-functions-maven-plugin (or Gradle plug-in) version 1.38.0 or a higher version.