[Feature Request] Activity result exceeding grpc size limit should log to ILogger

[RemyBoyer]

Is your feature request related to a problem? Please describe.

When an activity returns a payload that exceeds 4MB, a console log is written:

2026-07-13T09:48:03.195462Z  WARN temporalio_sdk_core::worker::activities: Network error while completing activity error=Status { code: ResourceExhausted, message: "grpc: received message larger than max (4194546 vs. 4194304)", metadata: MetadataMap { headers: {"content-type": "application/grpc", "message-too-large": "0"} }, source: None }

Describe the solution you'd like

It would be helpful if this error could be logged to ILogger too. Since as described here the default behavior is that the activity gets stuck, we've seen users wonder why their workflow doesn't progress.
They have looked at the sent telemetry, but since the console logs aren't sent to the OTEL collector in our case, they didn't see the error.

Giving those logs (and perhaps others) to ILogger could help spotting the issue.

Additional context

I'm also wondering how this is dealt with in other SDKs.

[jmaeagle99]

This is supported today but requires customers to wire it up. There is a set of options in the runtime construction that allow you to specify an ILogger: https://dotnet.temporal.io/api/Temporalio.Runtime.LogForwardingOptions.html#Temporalio_Runtime_LogForwardingOptions_Logger

The customer would write up something like:

var runtime = new TemporalRuntime(new()
{
    Telemetry = new()
    {
        Logging = new()
        {
            Forwarding = new(myILogger),
        },
    },
});
var client = await TemporalClient.ConnectAsync(new("localhost:7233") { Runtime = runtime });

This is the case for most core-based SDKs where the customer has to wire it up themselves. I believe Ruby is the exception in that it just writes to stdout/stderr.

I cannot find any .NET documentation for this, so maybe we can update the repo docs and samples to demonstrate this.

We might be able to make it easier in a DI setup for .NET by exposing a property to tell the dependency injection configuration to wire it up automatically. Not completely certain it's possible, but something we can look into.

[RemyBoyer]

Thanks, it's indeed exactly what we needed.

It would be nice to document it indeed, like some others TemporalRuntime already are, like the CustomMetricMeter.

We have an internal nuget packages that is used by all our apps and sets up the TemporalClient corrrectly (OTEL, Codec, dev server detection, ...).

Setting the Logger while still letting the apps to customize the runtime (they do it for the metrics already) would look like that:

public IServiceCollection AddOursTemporalCloudClient(
            string endpoint,
            string @namespace,
            string? apiKey,
            Action<TemporalClientConnectOptions>? configureClientOptions = null,
            Func<IServiceProvider, TemporalRuntimeOptions>? provideTemporalRuntimeOptions = null)
        {
            services.AddTemporalClient(endpoint, @namespace)
                .Configure((Action<TemporalClientConnectOptions, IServiceProvider>)((options, provider) =>
                {
                    // previous configuration (OTEL, Codec) goes here...
            
                    if (options.Runtime is not null)
                    {
                        throw new InvalidOperationException(
                            $"Do not set `{nameof(TemporalClientConnectOptions)}.{nameof(TemporalClientConnectOptions.Runtime)}` directly. Instead, use the argument `{nameof(temporalRuntimeOptions)}`");
                    }
            
                    var runtimeOptions = provideTemporalRuntimeOptions?.Invoke(provider) ?? new TemporalRuntimeOptions();
            
                    if (runtimeOptions.Telemetry.Logging?.Forwarding?.Logger is not null)
                    {
                        throw new InvalidOperationException(
                            $"Do not set `{nameof(TemporalRuntimeOptions)}.{nameof(TemporalRuntimeOptions.Telemetry)}.{nameof(TelemetryOptions.Logging)}.{nameof(LoggingOptions.Forwarding)}.{nameof(LogForwardingOptions.Logger)}` directly. It is meant to be set by the client.");
                    }
            
                    runtimeOptions.Telemetry.Logging ??= new LoggingOptions();
                    runtimeOptions.Telemetry.Logging.Forwarding ??= new LogForwardingOptions();
                    runtimeOptions.Telemetry.Logging.Forwarding.Logger = provider.GetRequiredService<ILogger<TemporalRuntime>>();
            
                    options.Runtime = new TemporalRuntime(runtimeOptions);
                }));

It could indeed be interesting if that was a simple boolean flag on TemporalClientConnectOptions or something. And maybe the above can already be improved.
But I'm happy we can already do it.