Provide ability to handle output binding failures in JavaScript

[paulbatum]

If you're writing a function that is using a trigger type that has no built-in retry such as a HTTP or Event Hubs there is no way to handle errors that occur when executing output bindings. This can result in the loss of data. The same is not true in C#, because types such as IAsyncCollector can be used and flushed while in user code e.g.

        public static async Task Run(
            EventData sensorEvent,            
            IAsyncCollector<EventData> outputWeatherData,            
            TraceWriter log)
        {
            var message = new WeatherData
            {
                SensorId = $"Sensor_1",
                Humidity = 12,
                Precipitation = 12,
                Temperature = 80
            };

            try
            {
                await outputWeatherData.AddAsync(new EventData(JsonSerializerHelper.ToByteArray(message)));            
                await outputWeatherData.FlushAsync();
            }
            catch(Exception e)
            {
                // handle error
            }
        }

A good JavaScript experience might look something like this:

module.exports = function (context, myQueueItem) {
    context.log('JavaScript queue trigger function processed work item', myQueueItem);    
    context.done(null, { myOutput: { text: 'hello there, world', noNumber: true }}, function(err) {
        // handle output binding errors
    });
};

[christopheranderson]

I'll work on a design for this. We should try to get to this in 2.x

[MikeStall]

I think @mathewc 's error filter work would provide a solution for this.

[mathewc]

Yes - for Azure/azure-webjobs-sdk#980 we're enabling exception filters that can handle ALL execution errors.

[pragnagopa]

Closing as the fix for Azure/azure-webjobs-sdk#980 is now available