Compute LRO exceptions drop structured operation error details

[Gezi-lzq]

Description

When a Compute Engine long-running operation completes with status: DONE and an operation-level error, the Java client exception produced by OperationFuture.get() appears to keep only httpErrorStatusCode / httpErrorMessage in the exception message. Structured details under operation.error.errors[] are not included, which can discard the actionable provider error.

Example operation payload shape:

status: DONE
error.errors[0].code: INVALID_USAGE
error.errors[0].message: No attached disk found with device name '<deviceName>'
httpErrorStatusCode: 400
httpErrorMessage: BAD REQUEST

The thrown exception message becomes similar to:

com.google.api.gax.rpc.InvalidArgumentException: Operation with name "..." failed with status = HttpJsonStatusCode{statusCode=INVALID_ARGUMENT} and message = BAD REQUEST

The important detail INVALID_USAGE: No attached disk found with device name ... is not present in the exception message.

Why this matters

For Compute operations such as InstancesClient.detachDiskAsync(...).get(), BAD REQUEST / INVALID_ARGUMENT is too generic for operators and applications to distinguish idempotent conditions from real invalid input. The structured operation error contains the actionable reason, but it is not surfaced by the default exception path.

Code path observed

Current generated Compute client code seems to build the REST LRO snapshot from only the HTTP error status/message:

• InstancesClient.detachDiskAsync(...) calls detachDiskOperationCallable().futureCall(request):
  

  google-cloud-java/java-compute/google-cloud-compute/src/main/java/com/google/cloud/compute/v1/InstancesClient.java

  Lines 2489 to 2531 in 58e50fc

  	public final OperationFuture<Operation, Operation> detachDiskAsync(
  	String project, String zone, String instance, String deviceName) {
  	DetachDiskInstanceRequest request =
  	DetachDiskInstanceRequest.newBuilder()
  	.setProject(project)
  	.setZone(zone)
  	.setInstance(instance)
  	.setDeviceName(deviceName)
  	.build();
  	return detachDiskAsync(request);
  	}
  	// AUTO-GENERATED DOCUMENTATION AND METHOD.
  	/**
  	* Detaches a disk from an instance.
  	*
  	* <p>Sample code:
  	*
  	* <pre>{@code
  	* // This snippet has been automatically generated and should be regarded as a code template only.
  	* // It will require modifications to work:
  	* // - It may require correct/in-range values for request initialization.
  	* // - It may require specifying regional endpoints when creating the service client as shown in
  	* // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
  	* try (InstancesClient instancesClient = InstancesClient.create()) {
  	* DetachDiskInstanceRequest request =
  	* DetachDiskInstanceRequest.newBuilder()
  	* .setDeviceName("deviceName780988929")
  	* .setInstance("instance555127957")
  	* .setProject("project-309310695")
  	* .setRequestId("requestId693933066")
  	* .setZone("zone3744684")
  	* .build();
  	* Operation response = instancesClient.detachDiskAsync(request).get();
  	* }
  	* }</pre>
  	*
  	* @param request The request object containing all of the parameters for the API call.
  	* @throws com.google.api.gax.rpc.ApiException if the remote call fails
  	*/
  	public final OperationFuture<Operation, Operation> detachDiskAsync(
  	DetachDiskInstanceRequest request) {
  	return detachDiskOperationCallable().futureCall(request);

• HttpJsonInstancesStub detach disk operation snapshot uses only response.getHttpErrorStatusCode() and response.getHttpErrorMessage():
  

  google-cloud-java/java-compute/google-cloud-compute/src/main/java/com/google/cloud/compute/v1/stub/HttpJsonInstancesStub.java

  Lines 671 to 682 in 58e50fc

  	.setOperationSnapshotFactory(
  	(DetachDiskInstanceRequest request, Operation response) -> {
  	StringBuilder opName = new StringBuilder(response.getName());
  	opName.append(":").append(request.getProject());
  	opName.append(":").append(request.getZone());
  	return HttpJsonOperationSnapshot.newBuilder()
  	.setName(opName.toString())
  	.setMetadata(response)
  	.setDone(Status.DONE.equals(response.getStatus()))
  	.setResponse(response)
  	.setError(response.getHttpErrorStatusCode(), response.getHttpErrorMessage())
  	.build();

• InstancesStubSettings wires this into ProtoOperationTransformers.ResponseTransformer.create(Operation.class):
  

  google-cloud-java/java-compute/google-cloud-compute/src/main/java/com/google/cloud/compute/v1/stub/InstancesStubSettings.java

  Lines 2294 to 2305 in 58e50fc

  	builder
  	.detachDiskOperationSettings()
  	.setInitialCallSettings(
  	UnaryCallSettings
  	.<DetachDiskInstanceRequest, OperationSnapshot>newUnaryCallSettingsBuilder()
  	.setRetryableCodes(RETRYABLE_CODE_DEFINITIONS.get("no_retry_1_codes"))
  	.setRetrySettings(RETRY_PARAM_DEFINITIONS.get("no_retry_1_params"))
  	.build())
  	.setResponseTransformer(
  	ProtoOperationTransformers.ResponseTransformer.create(Operation.class))
  	.setMetadataTransformer(
  	ProtoOperationTransformers.MetadataTransformer.create(Operation.class))

In gax, the response transformer creates the exception message from operationSnapshot.getErrorCode() and operationSnapshot.getErrorMessage() only:

• https://github.com/googleapis/sdk-platform-java/blob/febe86f1ea4f0b5e6d8454024ed499adb7dc9328/gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/ProtoOperationTransformers.java#L52-L65

HTTP 400 is then mapped to INVALID_ARGUMENT, and ApiExceptionFactory maps that to InvalidArgumentException:

• https://github.com/googleapis/sdk-platform-java/blob/febe86f1ea4f0b5e6d8454024ed499adb7dc9328/gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonStatusCode.java#L96-L103
• https://github.com/googleapis/sdk-platform-java/blob/febe86f1ea4f0b5e6d8454024ed499adb7dc9328/gax-java/gax/src/main/java/com/google/api/gax/rpc/ApiExceptionFactory.java#L44-L53

Expected behavior

When the operation response contains structured error details, the thrown exception should expose or preserve them. For example, the exception message or an accessible error detail field should include something like:

INVALID_USAGE: No attached disk found with device name '<deviceName>'

Actual behavior

The default exception message only includes:

status = HttpJsonStatusCode{statusCode=INVALID_ARGUMENT} and message = BAD REQUEST

Possible fixes

• Include Operation.error.errors[] in the generated Compute OperationSnapshot error message, where available.
• Or preserve the original Compute Operation error details in the gax exception / ErrorDetails so callers can inspect them programmatically.
• Or provide documented guidance for retrieving the full failed operation response after OperationFuture.get() throws.

If this belongs in googleapis/sdk-platform-java instead of this generated client repo, please redirect or transfer. The generated Compute client appears to be where the Compute-specific Operation.error.errors[] data is first collapsed into generic HTTP status/message.